zephyr/drivers/crypto/crypto_mtls_shim.c

620 lines
15 KiB
C

/*
* Copyright (c) 2017 Intel Corporation.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file Shim layer for mbedTLS, crypto API compliant.
*/
#include <zephyr/kernel.h>
#include <zephyr/init.h>
#include <errno.h>
#include <zephyr/crypto/crypto.h>
#if !defined(CONFIG_MBEDTLS_CFG_FILE)
#include "mbedtls/config.h"
#else
#include CONFIG_MBEDTLS_CFG_FILE
#endif /* CONFIG_MBEDTLS_CFG_FILE */
#include <mbedtls/ccm.h>
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
#include <mbedtls/gcm.h>
#endif
#include <mbedtls/aes.h>
#include <mbedtls/sha256.h>
#include <mbedtls/sha512.h>
#define MTLS_SUPPORT (CAP_RAW_KEY | CAP_SEPARATE_IO_BUFS | CAP_SYNC_OPS | \
CAP_NO_IV_PREFIX)
#define LOG_LEVEL CONFIG_CRYPTO_LOG_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(mbedtls);
struct mtls_shim_session {
union {
mbedtls_ccm_context mtls_ccm;
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
mbedtls_gcm_context mtls_gcm;
#endif
mbedtls_aes_context mtls_aes;
mbedtls_sha256_context mtls_sha256;
mbedtls_sha512_context mtls_sha512;
};
bool in_use;
union {
enum cipher_mode mode;
enum hash_algo algo;
};
};
#define CRYPTO_MAX_SESSION CONFIG_CRYPTO_MBEDTLS_SHIM_MAX_SESSION
struct mtls_shim_session mtls_sessions[CRYPTO_MAX_SESSION];
#if defined(MBEDTLS_MEMORY_BUFFER_ALLOC_C)
#include "mbedtls/memory_buffer_alloc.h"
#else
#error "You need to define MBEDTLS_MEMORY_BUFFER_ALLOC_C"
#endif /* MBEDTLS_MEMORY_BUFFER_ALLOC_C */
#define MTLS_GET_CTX(c, m) \
(&((struct mtls_shim_session *)c->drv_sessn_state)->mtls_ ## m)
#define MTLS_GET_ALGO(c) \
(((struct mtls_shim_session *)c->drv_sessn_state)->algo)
int mtls_ecb_encrypt(struct cipher_ctx *ctx, struct cipher_pkt *pkt)
{
int ret;
mbedtls_aes_context *ecb_ctx = MTLS_GET_CTX(ctx, aes);
/* For security reasons, ECB mode should not be used to encrypt
* more than one block. Use CBC mode instead.
*/
if (pkt->in_len > 16) {
LOG_ERR("Cannot encrypt more than 1 block");
return -EINVAL;
}
ret = mbedtls_aes_crypt_ecb(ecb_ctx, MBEDTLS_AES_ENCRYPT,
pkt->in_buf, pkt->out_buf);
if (ret) {
LOG_ERR("Could not encrypt (%d)", ret);
return -EINVAL;
}
pkt->out_len = 16;
return 0;
}
int mtls_ecb_decrypt(struct cipher_ctx *ctx, struct cipher_pkt *pkt)
{
int ret;
mbedtls_aes_context *ecb_ctx = MTLS_GET_CTX(ctx, aes);
/* For security reasons, ECB mode should not be used to decrypt
* more than one block. Use CBC mode instead.
*/
if (pkt->in_len > 16) {
LOG_ERR("Cannot decrypt more than 1 block");
return -EINVAL;
}
ret = mbedtls_aes_crypt_ecb(ecb_ctx, MBEDTLS_AES_DECRYPT,
pkt->in_buf, pkt->out_buf);
if (ret) {
LOG_ERR("Could not encrypt (%d)", ret);
return -EINVAL;
}
pkt->out_len = 16;
return 0;
}
int mtls_cbc_encrypt(struct cipher_ctx *ctx, struct cipher_pkt *pkt, uint8_t *iv)
{
int ret, iv_bytes;
uint8_t *p_iv, iv_loc[16];
mbedtls_aes_context *cbc_ctx = MTLS_GET_CTX(ctx, aes);
if ((ctx->flags & CAP_NO_IV_PREFIX) == 0U) {
/* Prefix IV to ciphertext, which is default behavior of Zephyr
* crypto API, unless CAP_NO_IV_PREFIX is requested.
*/
iv_bytes = 16;
memcpy(pkt->out_buf, iv, 16);
p_iv = iv;
} else {
iv_bytes = 0;
memcpy(iv_loc, iv, 16);
p_iv = iv_loc;
}
ret = mbedtls_aes_crypt_cbc(cbc_ctx, MBEDTLS_AES_ENCRYPT, pkt->in_len,
p_iv, pkt->in_buf, pkt->out_buf + iv_bytes);
if (ret) {
LOG_ERR("Could not encrypt (%d)", ret);
return -EINVAL;
}
pkt->out_len = pkt->in_len + iv_bytes;
return 0;
}
int mtls_cbc_decrypt(struct cipher_ctx *ctx, struct cipher_pkt *pkt, uint8_t *iv)
{
int ret, iv_bytes;
uint8_t *p_iv, iv_loc[16];
mbedtls_aes_context *cbc_ctx = MTLS_GET_CTX(ctx, aes);
if ((ctx->flags & CAP_NO_IV_PREFIX) == 0U) {
iv_bytes = 16;
p_iv = iv;
} else {
iv_bytes = 0;
memcpy(iv_loc, iv, 16);
p_iv = iv_loc;
}
ret = mbedtls_aes_crypt_cbc(cbc_ctx, MBEDTLS_AES_DECRYPT, pkt->in_len,
p_iv, pkt->in_buf + iv_bytes, pkt->out_buf);
if (ret) {
LOG_ERR("Could not encrypt (%d)", ret);
return -EINVAL;
}
pkt->out_len = pkt->in_len - iv_bytes;
return 0;
}
static int mtls_ccm_encrypt_auth(struct cipher_ctx *ctx,
struct cipher_aead_pkt *apkt,
uint8_t *nonce)
{
mbedtls_ccm_context *mtls_ctx = MTLS_GET_CTX(ctx, ccm);
int ret;
ret = mbedtls_ccm_encrypt_and_tag(mtls_ctx, apkt->pkt->in_len, nonce,
ctx->mode_params.ccm_info.nonce_len,
apkt->ad, apkt->ad_len,
apkt->pkt->in_buf,
apkt->pkt->out_buf, apkt->tag,
ctx->mode_params.ccm_info.tag_len);
if (ret) {
LOG_ERR("Could not encrypt/auth (%d)", ret);
/*ToDo: try to return relevant code depending on ret? */
return -EINVAL;
}
/* This is equivalent to what the TinyCrypt shim does in
* do_ccm_encrypt_mac().
*/
apkt->pkt->out_len = apkt->pkt->in_len;
apkt->pkt->out_len += ctx->mode_params.ccm_info.tag_len;
return 0;
}
static int mtls_ccm_decrypt_auth(struct cipher_ctx *ctx,
struct cipher_aead_pkt *apkt,
uint8_t *nonce)
{
mbedtls_ccm_context *mtls_ctx = MTLS_GET_CTX(ctx, ccm);
int ret;
ret = mbedtls_ccm_auth_decrypt(mtls_ctx, apkt->pkt->in_len, nonce,
ctx->mode_params.ccm_info.nonce_len,
apkt->ad, apkt->ad_len,
apkt->pkt->in_buf,
apkt->pkt->out_buf, apkt->tag,
ctx->mode_params.ccm_info.tag_len);
if (ret) {
if (ret == MBEDTLS_ERR_CCM_AUTH_FAILED) {
LOG_ERR("Message authentication failed");
return -EFAULT;
}
LOG_ERR("Could not decrypt/auth (%d)", ret);
/*ToDo: try to return relevant code depending on ret? */
return -EINVAL;
}
apkt->pkt->out_len = apkt->pkt->in_len;
apkt->pkt->out_len += ctx->mode_params.ccm_info.tag_len;
return 0;
}
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
static int mtls_gcm_encrypt_auth(struct cipher_ctx *ctx,
struct cipher_aead_pkt *apkt,
uint8_t *nonce)
{
mbedtls_gcm_context *mtls_ctx = MTLS_GET_CTX(ctx, gcm);
int ret;
ret = mbedtls_gcm_crypt_and_tag(mtls_ctx, MBEDTLS_GCM_ENCRYPT,
apkt->pkt->in_len, nonce,
ctx->mode_params.gcm_info.nonce_len,
apkt->ad, apkt->ad_len,
apkt->pkt->in_buf,
apkt->pkt->out_buf,
ctx->mode_params.gcm_info.tag_len,
apkt->tag);
if (ret) {
LOG_ERR("Could not encrypt/auth (%d)", ret);
return -EINVAL;
}
/* This is equivalent to what is done in mtls_ccm_encrypt_auth(). */
apkt->pkt->out_len = apkt->pkt->in_len;
apkt->pkt->out_len += ctx->mode_params.gcm_info.tag_len;
return 0;
}
static int mtls_gcm_decrypt_auth(struct cipher_ctx *ctx,
struct cipher_aead_pkt *apkt,
uint8_t *nonce)
{
mbedtls_gcm_context *mtls_ctx = MTLS_GET_CTX(ctx, gcm);
int ret;
ret = mbedtls_gcm_auth_decrypt(mtls_ctx, apkt->pkt->in_len, nonce,
ctx->mode_params.gcm_info.nonce_len,
apkt->ad, apkt->ad_len,
apkt->tag,
ctx->mode_params.gcm_info.tag_len,
apkt->pkt->in_buf,
apkt->pkt->out_buf);
if (ret) {
if (ret == MBEDTLS_ERR_GCM_AUTH_FAILED) {
LOG_ERR("Message authentication failed");
return -EFAULT;
}
LOG_ERR("Could not decrypt/auth (%d)", ret);
return -EINVAL;
}
apkt->pkt->out_len = apkt->pkt->in_len;
apkt->pkt->out_len += ctx->mode_params.gcm_info.tag_len;
return 0;
}
#endif /* CONFIG_MBEDTLS_CIPHER_GCM_ENABLED */
static int mtls_get_unused_session_index(void)
{
int i;
for (i = 0; i < CRYPTO_MAX_SESSION; i++) {
if (!mtls_sessions[i].in_use) {
mtls_sessions[i].in_use = true;
return i;
}
}
return -1;
}
static int mtls_session_setup(const struct device *dev,
struct cipher_ctx *ctx,
enum cipher_algo algo, enum cipher_mode mode,
enum cipher_op op_type)
{
mbedtls_aes_context *aes_ctx;
mbedtls_ccm_context *ccm_ctx;
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
mbedtls_gcm_context *gcm_ctx;
#endif
int ctx_idx;
int ret;
if (ctx->flags & ~(MTLS_SUPPORT)) {
LOG_ERR("Unsupported flag");
return -EINVAL;
}
if (algo != CRYPTO_CIPHER_ALGO_AES) {
LOG_ERR("Unsupported algo");
return -EINVAL;
}
if (mode != CRYPTO_CIPHER_MODE_CCM &&
mode != CRYPTO_CIPHER_MODE_CBC &&
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
mode != CRYPTO_CIPHER_MODE_GCM &&
#endif
mode != CRYPTO_CIPHER_MODE_ECB) {
LOG_ERR("Unsupported mode");
return -EINVAL;
}
if (ctx->keylen != 16U) {
LOG_ERR("%u key size is not supported", ctx->keylen);
return -EINVAL;
}
ctx_idx = mtls_get_unused_session_index();
if (ctx_idx < 0) {
LOG_ERR("No free session for now");
return -ENOSPC;
}
switch (mode) {
case CRYPTO_CIPHER_MODE_ECB:
aes_ctx = &mtls_sessions[ctx_idx].mtls_aes;
mbedtls_aes_init(aes_ctx);
if (op_type == CRYPTO_CIPHER_OP_ENCRYPT) {
ret = mbedtls_aes_setkey_enc(aes_ctx,
ctx->key.bit_stream, ctx->keylen * 8U);
ctx->ops.block_crypt_hndlr = mtls_ecb_encrypt;
} else {
ret = mbedtls_aes_setkey_dec(aes_ctx,
ctx->key.bit_stream, ctx->keylen * 8U);
ctx->ops.block_crypt_hndlr = mtls_ecb_decrypt;
}
if (ret) {
LOG_ERR("AES_ECB: failed at setkey (%d)", ret);
ctx->ops.block_crypt_hndlr = NULL;
mtls_sessions[ctx_idx].in_use = false;
return -EINVAL;
}
break;
case CRYPTO_CIPHER_MODE_CBC:
aes_ctx = &mtls_sessions[ctx_idx].mtls_aes;
mbedtls_aes_init(aes_ctx);
if (op_type == CRYPTO_CIPHER_OP_ENCRYPT) {
ret = mbedtls_aes_setkey_enc(aes_ctx,
ctx->key.bit_stream, ctx->keylen * 8U);
ctx->ops.cbc_crypt_hndlr = mtls_cbc_encrypt;
} else {
ret = mbedtls_aes_setkey_dec(aes_ctx,
ctx->key.bit_stream, ctx->keylen * 8U);
ctx->ops.cbc_crypt_hndlr = mtls_cbc_decrypt;
}
if (ret) {
LOG_ERR("AES_CBC: failed at setkey (%d)", ret);
ctx->ops.cbc_crypt_hndlr = NULL;
mtls_sessions[ctx_idx].in_use = false;
return -EINVAL;
}
break;
case CRYPTO_CIPHER_MODE_CCM:
ccm_ctx = &mtls_sessions[ctx_idx].mtls_ccm;
mbedtls_ccm_init(ccm_ctx);
ret = mbedtls_ccm_setkey(ccm_ctx, MBEDTLS_CIPHER_ID_AES,
ctx->key.bit_stream, ctx->keylen * 8U);
if (ret) {
LOG_ERR("AES_CCM: failed at setkey (%d)", ret);
mtls_sessions[ctx_idx].in_use = false;
return -EINVAL;
}
if (op_type == CRYPTO_CIPHER_OP_ENCRYPT) {
ctx->ops.ccm_crypt_hndlr = mtls_ccm_encrypt_auth;
} else {
ctx->ops.ccm_crypt_hndlr = mtls_ccm_decrypt_auth;
}
break;
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
case CRYPTO_CIPHER_MODE_GCM:
gcm_ctx = &mtls_sessions[ctx_idx].mtls_gcm;
mbedtls_gcm_init(gcm_ctx);
ret = mbedtls_gcm_setkey(gcm_ctx, MBEDTLS_CIPHER_ID_AES,
ctx->key.bit_stream, ctx->keylen * 8U);
if (ret) {
LOG_ERR("AES_GCM: failed at setkey (%d)", ret);
mtls_sessions[ctx_idx].in_use = false;
return -EINVAL;
}
if (op_type == CRYPTO_CIPHER_OP_ENCRYPT) {
ctx->ops.gcm_crypt_hndlr = mtls_gcm_encrypt_auth;
} else {
ctx->ops.gcm_crypt_hndlr = mtls_gcm_decrypt_auth;
}
break;
#endif /* CONFIG_MBEDTLS_CIPHER_GCM_ENABLED */
default:
LOG_ERR("Unhandled mode");
mtls_sessions[ctx_idx].in_use = false;
return -EINVAL;
}
mtls_sessions[ctx_idx].mode = mode;
ctx->drv_sessn_state = &mtls_sessions[ctx_idx];
return ret;
}
static int mtls_session_free(const struct device *dev, struct cipher_ctx *ctx)
{
struct mtls_shim_session *mtls_session =
(struct mtls_shim_session *)ctx->drv_sessn_state;
if (mtls_session->mode == CRYPTO_CIPHER_MODE_CCM) {
mbedtls_ccm_free(&mtls_session->mtls_ccm);
#ifdef CONFIG_MBEDTLS_CIPHER_GCM_ENABLED
} else if (mtls_session->mode == CRYPTO_CIPHER_MODE_GCM) {
mbedtls_gcm_free(&mtls_session->mtls_gcm);
#endif
} else {
mbedtls_aes_free(&mtls_session->mtls_aes);
}
mtls_session->in_use = false;
return 0;
}
static int mtls_sha256_compute(struct hash_ctx *ctx, struct hash_pkt *pkt,
bool finish)
{
int ret;
mbedtls_sha256_context *sha256_ctx = MTLS_GET_CTX(ctx, sha256);
if (!ctx->started) {
ret = mbedtls_sha256_starts(sha256_ctx,
MTLS_GET_ALGO(ctx) == CRYPTO_HASH_ALGO_SHA224);
if (ret != 0) {
LOG_ERR("Could not compute the hash");
return -EINVAL;
}
ctx->started = true;
}
ret = mbedtls_sha256_update(sha256_ctx, pkt->in_buf, pkt->in_len);
if (ret != 0) {
LOG_ERR("Could not update the hash");
ctx->started = false;
return -EINVAL;
}
if (finish) {
ctx->started = false;
ret = mbedtls_sha256_finish(sha256_ctx, pkt->out_buf);
if (ret != 0) {
LOG_ERR("Could not compute the hash");
return -EINVAL;
}
}
return 0;
}
static int mtls_sha512_compute(struct hash_ctx *ctx, struct hash_pkt *pkt,
bool finish)
{
int ret;
mbedtls_sha512_context *sha512_ctx = MTLS_GET_CTX(ctx, sha512);
if (!ctx->started) {
ret = mbedtls_sha512_starts(sha512_ctx,
MTLS_GET_ALGO(ctx) == CRYPTO_HASH_ALGO_SHA384);
if (ret != 0) {
LOG_ERR("Could not compute the hash");
return -EINVAL;
}
ctx->started = true;
}
ret = mbedtls_sha512_update(sha512_ctx, pkt->in_buf, pkt->in_len);
if (ret != 0) {
LOG_ERR("Could not update the hash");
ctx->started = false;
return -EINVAL;
}
if (finish) {
ctx->started = false;
ret = mbedtls_sha512_finish(sha512_ctx, pkt->out_buf);
if (ret != 0) {
LOG_ERR("Could not compute the hash");
return -EINVAL;
}
}
return 0;
}
static int mtls_hash_session_setup(const struct device *dev,
struct hash_ctx *ctx,
enum hash_algo algo)
{
int ctx_idx;
if (ctx->flags & ~(MTLS_SUPPORT)) {
LOG_ERR("Unsupported flag");
return -EINVAL;
}
if ((algo != CRYPTO_HASH_ALGO_SHA224) &&
(algo != CRYPTO_HASH_ALGO_SHA256) &&
(algo != CRYPTO_HASH_ALGO_SHA384) &&
(algo != CRYPTO_HASH_ALGO_SHA512)) {
LOG_ERR("Unsupported algo: %d", algo);
return -EINVAL;
}
ctx_idx = mtls_get_unused_session_index();
if (ctx_idx < 0) {
LOG_ERR("No free session for now");
return -ENOSPC;
}
mtls_sessions[ctx_idx].algo = algo;
ctx->drv_sessn_state = &mtls_sessions[ctx_idx];
ctx->started = false;
if ((algo == CRYPTO_HASH_ALGO_SHA224) ||
(algo == CRYPTO_HASH_ALGO_SHA256)) {
mbedtls_sha256_context *sha256_ctx =
&mtls_sessions[ctx_idx].mtls_sha256;
mbedtls_sha256_init(sha256_ctx);
ctx->hash_hndlr = mtls_sha256_compute;
} else {
mbedtls_sha512_context *sha512_ctx =
&mtls_sessions[ctx_idx].mtls_sha512;
mbedtls_sha512_init(sha512_ctx);
ctx->hash_hndlr = mtls_sha512_compute;
}
return 0;
}
static int mtls_hash_session_free(const struct device *dev, struct hash_ctx *ctx)
{
struct mtls_shim_session *mtls_session =
(struct mtls_shim_session *)ctx->drv_sessn_state;
if (mtls_session->algo == CRYPTO_HASH_ALGO_SHA256) {
mbedtls_sha256_free(&mtls_session->mtls_sha256);
} else {
mbedtls_sha512_free(&mtls_session->mtls_sha512);
}
mtls_session->in_use = false;
return 0;
}
static int mtls_query_caps(const struct device *dev)
{
return MTLS_SUPPORT;
}
static int mtls_shim_init(const struct device *dev)
{
return 0;
}
static struct crypto_driver_api mtls_crypto_funcs = {
.cipher_begin_session = mtls_session_setup,
.cipher_free_session = mtls_session_free,
.cipher_async_callback_set = NULL,
.hash_begin_session = mtls_hash_session_setup,
.hash_free_session = mtls_hash_session_free,
.query_hw_caps = mtls_query_caps,
};
DEVICE_DEFINE(crypto_mtls, CONFIG_CRYPTO_MBEDTLS_SHIM_DRV_NAME,
&mtls_shim_init, NULL, NULL, NULL,
POST_KERNEL, CONFIG_CRYPTO_INIT_PRIORITY,
(void *)&mtls_crypto_funcs);