osd-contiki/core/net/mac/tsch/tsch-security.c

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/*
* Copyright (c) 2014, SICS Swedish ICT.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
*/
/**
* \file
* TSCH security
* \author
* Simon Duquennoy <simonduq@sics.se>
*/
#include "contiki.h"
#include "net/mac/tsch/tsch.h"
#include "net/mac/tsch/tsch-packet.h"
#include "net/mac/tsch/tsch-private.h"
#include "net/mac/tsch/tsch-schedule.h"
#include "net/mac/tsch/tsch-security.h"
#include "net/mac/tsch/tsch-log.h"
#include "net/mac/frame802154.h"
#include "net/mac/framer-802154.h"
#include "net/netstack.h"
#include "net/packetbuf.h"
#include "lib/ccm-star.h"
#include "lib/aes-128.h"
#include <stdio.h>
#include <string.h>
#if TSCH_LOG_LEVEL >= 1
#define DEBUG DEBUG_PRINT
#else /* TSCH_LOG_LEVEL */
#define DEBUG DEBUG_NONE
#endif /* TSCH_LOG_LEVEL */
#include "net/net-debug.h"
/* The two keys K1 and K2 from 6TiSCH minimal configuration
* K1: well-known, used for EBs
* K2: secret, used for data and ACK
* */
static aes_key keys[] = {
TSCH_SECURITY_K1,
TSCH_SECURITY_K2
};
#define N_KEYS (sizeof(keys) / sizeof(aes_key))
/*---------------------------------------------------------------------------*/
static void
tsch_security_init_nonce(uint8_t *nonce,
const linkaddr_t *sender, struct asn_t *asn)
{
memcpy(nonce, sender, 8);
nonce[8] = asn->ms1b;
nonce[9] = (asn->ls4b >> 24) & 0xff;
nonce[10] = (asn->ls4b >> 16) & 0xff;
nonce[11] = (asn->ls4b >> 8) & 0xff;
nonce[12] = (asn->ls4b) & 0xff;
}
/*---------------------------------------------------------------------------*/
static int
tsch_security_check_level(const frame802154_t *frame)
{
uint8_t required_security_level;
uint8_t required_key_index;
/* Sanity check */
if(frame == NULL) {
return 0;
}
/* Non-secured frame, ok iff we are not in a secured PAN
* (i.e. scanning or associated to a non-secured PAN) */
if(frame->fcf.security_enabled == 0) {
return !(tsch_is_associated == 1 && tsch_is_pan_secured == 1);
}
/* The frame is secured, that we are not in an unsecured PAN */
if(tsch_is_associated == 1 && tsch_is_pan_secured == 0) {
return 0;
}
/* The frame is secured, check its security level */
switch(frame->fcf.frame_type) {
case FRAME802154_BEACONFRAME:
required_security_level = TSCH_SECURITY_KEY_SEC_LEVEL_EB;
required_key_index = TSCH_SECURITY_KEY_INDEX_EB;
break;
case FRAME802154_ACKFRAME:
required_security_level = TSCH_SECURITY_KEY_SEC_LEVEL_ACK;
required_key_index = TSCH_SECURITY_KEY_INDEX_ACK;
break;
default:
required_security_level = TSCH_SECURITY_KEY_SEC_LEVEL_OTHER;
required_key_index = TSCH_SECURITY_KEY_INDEX_OTHER;
break;
}
return frame->aux_hdr.security_control.security_level == required_security_level
&& frame->aux_hdr.key_index == required_key_index;
}
/*---------------------------------------------------------------------------*/
int
tsch_security_mic_len(const frame802154_t *frame)
{
if(frame != NULL && frame->fcf.security_enabled) {
return 2 << (frame->aux_hdr.security_control.security_level & 0x03);
} else {
return 0;
}
}
/*---------------------------------------------------------------------------*/
int
tsch_security_secure_frame(uint8_t *hdr, uint8_t *outbuf,
int hdrlen, int datalen, struct asn_t *asn)
{
frame802154_t frame;
uint8_t key_index = 0;
uint8_t security_level = 0;
uint8_t with_encryption;
uint8_t mic_len;
uint8_t nonce[16];
uint8_t a_len;
uint8_t m_len;
if(hdr == NULL || outbuf == NULL || hdrlen < 0 || datalen < 0) {
return 0;
}
/* Parse the frame header to extract security settings */
if(frame802154_parse(hdr, hdrlen + datalen, &frame) < 3) {
return 0;
}
if(!frame.fcf.security_enabled) {
/* Security is not enabled for this frame, we're done */
return 1;
}
/* Read security key index */
key_index = frame.aux_hdr.key_index;
security_level = frame.aux_hdr.security_control.security_level;
with_encryption = (security_level & 0x4) ? 1 : 0;
mic_len = tsch_security_mic_len(&frame);
if(key_index == 0 || key_index > N_KEYS) {
return 0;
}
tsch_security_init_nonce(nonce, &linkaddr_node_addr, asn);
if(with_encryption) {
a_len = hdrlen;
m_len = datalen;
} else {
a_len = hdrlen + datalen;
m_len = 0;
}
/* Copy source data to output */
if(hdr != outbuf) {
memcpy(outbuf, hdr, a_len + m_len);
}
CCM_STAR.set_key(keys[key_index - 1]);
CCM_STAR.aead(nonce,
outbuf + a_len, m_len,
outbuf, a_len,
outbuf + hdrlen + datalen, mic_len, 1
);
return mic_len;
}
/*---------------------------------------------------------------------------*/
int
tsch_security_parse_frame(const uint8_t *hdr, int hdrlen, int datalen,
const frame802154_t *frame, const linkaddr_t *sender, struct asn_t *asn)
{
uint8_t generated_mic[16];
uint8_t key_index = 0;
uint8_t security_level = 0;
uint8_t with_encryption;
uint8_t mic_len;
uint8_t nonce[16];
uint8_t a_len;
uint8_t m_len;
if(frame == NULL || hdr == NULL || hdrlen < 0 || datalen < 0) {
return 0;
}
if(!tsch_security_check_level(frame)) {
/* Wrong security level */
return 0;
}
/* No security: nothing more to check */
if(!frame->fcf.security_enabled) {
return 1;
}
key_index = frame->aux_hdr.key_index;
security_level = frame->aux_hdr.security_control.security_level;
with_encryption = (security_level & 0x4) ? 1 : 0;
mic_len = tsch_security_mic_len(frame);
/* Check if key_index is in supported range */
if(key_index == 0 || key_index > N_KEYS) {
return 0;
}
tsch_security_init_nonce(nonce, sender, asn);
if(with_encryption) {
a_len = hdrlen;
m_len = datalen;
} else {
a_len = hdrlen + datalen;
m_len = 0;
}
CCM_STAR.set_key(keys[key_index - 1]);
CCM_STAR.aead(nonce,
(uint8_t *)hdr + a_len, m_len,
(uint8_t *)hdr, a_len,
generated_mic, mic_len, 0
);
if(mic_len > 0 && memcmp(generated_mic, hdr + hdrlen + datalen, mic_len) != 0) {
return 0;
} else {
return 1;
}
}