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/**
* @file sad_nettle.c
* @brief Security Association Database nettle functions
* @note Copyright (C) 2024 IBM Corporation, Clay Kaiser <Clay.Kaiser@ibm.com>
* @note SPDX-License-Identifier: GPL-2.0+
*/
#include <nettle/hmac.h>
#include <nettle/memops.h>
#include <nettle/nettle-meta.h>
#include <stdlib.h>
#include <string.h>
#include <sys/queue.h>
#include "print.h"
#include "sad.h"
#include "sad_private.h"
struct mac_data {
const struct nettle_mac *nettle_mac;
void *context;
};
struct mac_data *sad_init_mac(integrity_alg_type algorithm,
const unsigned char *key, size_t key_len)
{
size_t i, length;
const char *name;
const struct nettle_mac *mac_algorithm = NULL;
struct mac_data *mac_data;
/* verify key length */
if (key_len == 0) {
pr_err("BUG: key_len is zero");
return NULL;
}
/* retrieve mac algorithm */
switch (algorithm) {
case HMAC_SHA256_128:
case HMAC_SHA256:
name = "hmac_sha256";
break;
case CMAC_AES128:
name = "cmac_aes128";
break;
case CMAC_AES256:
name = "cmac_aes256";
break;
default:
pr_err("BUG: unknown algorithm");
return NULL;
}
for (i = 0; nettle_macs[i]; i++) {
if (!strcmp(name, nettle_macs[i]->name)) {
mac_algorithm = nettle_macs[i];
break;
}
}
if (!mac_algorithm || !mac_algorithm->context_size || !mac_algorithm->set_key)
return NULL;
/* retrieve mac key length */
length = mac_algorithm->key_size;
/* verify key length matches for cmac only */
switch (algorithm) {
case CMAC_AES128:
case CMAC_AES256:
if (key_len != length) {
pr_err("BUG: cipher key_len does not match");
return NULL;
}
break;
default:
break;
}
/* initialize mac_data and context */
mac_data = calloc(1, sizeof(*mac_data));
if (!mac_data) {
return NULL;
}
mac_data->nettle_mac = mac_algorithm;
mac_data->context = calloc(1, mac_data->nettle_mac->context_size);
if (!mac_data->context) {
free(mac_data);
return NULL;
}
/* set key */
switch (algorithm) {
case HMAC_SHA256_128:
case HMAC_SHA256:
/* not able to use mac abstraction AND any length sha key */
hmac_sha256_set_key(mac_data->context, key_len, key);
break;
case CMAC_AES128:
case CMAC_AES256:
mac_data->nettle_mac->set_key(mac_data->context, key);
break;
default:
sad_deinit_mac(mac_data);
return NULL;
}
return mac_data;
}
void sad_deinit_mac(struct mac_data *mac_data)
{
free(mac_data->context);
free(mac_data);
}
int sad_hash(struct mac_data *mac_data,
const void *data, size_t data_len,
unsigned char *mac, size_t mac_len)
{
size_t digest_len;
/* confirm mac length is within library support */
digest_len = mac_data->nettle_mac->digest_size;
if (mac_len > digest_len) {
pr_err("BUG: mac_len larger than library support");
return 0;
}
/* confirm mac length is within buffer size */
if (mac_len > MAX_DIGEST_LENGTH) {
pr_err("BUG: mac_len larger than buffer");
return 0;
}
/* update data and retrieve mac */
mac_data->nettle_mac->update(mac_data->context, data_len, data);
mac_data->nettle_mac->digest(mac_data->context, mac_len, mac);
return mac_len;
}
int sad_verify(struct mac_data *mac_data,
const void *data, size_t data_len,
unsigned char *mac, size_t mac_len)
{
unsigned char digest_buf[MAX_DIGEST_LENGTH];
/* update data and retrieve mac */
if (!sad_hash(mac_data, data, data_len, digest_buf, mac_len)) {
return -1;
}
/* compare calculated with received */
return (memeql_sec(digest_buf, mac, mac_len) != 1);
}
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