/*FUNCTION:------------------------------------------------------
* NAME
* dissect_zbee_secure
* DESCRIPTION
* Dissects and decrypts secured ZigBee frames.
*
* Will return a valid tvbuff only if security processing was
* successful. If processing fails, then this function will
* handle internally and return NULL.
* PARAMETERS
* tvbuff_t *tvb - pointer to buffer containing raw packet.
* packet_info *pinfo - pointer to packet information fields
* proto_tree *tree - pointer to data tree Wireshark uses to display packet.
* guint offset - pointer to the start of the auxilliary security header.
* guint64 src64 - extended source address, or 0 if unknown.
* RETURNS
* tvbuff_t *
*---------------------------------------------------------------
*/
tvbuff_t *
dissect_zbee_secure(tvbuff_t *tvb, packet_info *pinfo, proto_tree* tree, guint offset)
{
proto_tree *sec_tree = NULL;
proto_item *sec_root;
proto_tree *field_tree;
proto_item *ti;
zbee_security_packet packet;
guint mic_len;
gint payload_len;
tvbuff_t *payload_tvb;
#ifdef HAVE_LIBGCRYPT
guint8 *enc_buffer;
guint8 *dec_buffer;
gboolean decrypted;
GSList **nwk_keyring;
GSList *GSList_i;
key_record_t *key_rec = NULL;
#endif
zbee_nwk_hints_t *nwk_hints;
ieee802154_hints_t *ieee_hints;
ieee802154_map_rec *map_rec = NULL;
/* Init */
memset(&packet, 0, sizeof(zbee_security_packet));
/* Get pointers to any useful frame data from lower layers */
nwk_hints = (zbee_nwk_hints_t *)p_get_proto_data(pinfo->fd, proto_get_id_by_filter_name(ZBEE_PROTOABBREV_NWK));
ieee_hints = (ieee802154_hints_t *)p_get_proto_data(pinfo->fd,
proto_get_id_by_filter_name(IEEE802154_PROTOABBREV_WPAN));
/* Create a subtree for the security information. */
if (tree) {
sec_root = proto_tree_add_text(tree, tvb, offset, tvb_length_remaining(tvb, offset), "ZigBee Security Header");
sec_tree = proto_item_add_subtree(sec_root, ett_zbee_sec);
}
/* Get and display the Security control field */
packet.control = tvb_get_guint8(tvb, offset);
/* Patch the security level. */
packet.control &= ~ZBEE_SEC_CONTROL_LEVEL;
packet.control |= (ZBEE_SEC_CONTROL_LEVEL & gPREF_zbee_sec_level);
/*
* Eww, I think I just threw up a little... ZigBee requires this field
* to be patched before computing the MIC, but we don't have write-access
* to the tvbuff. So we need to allocate a copy of the whole thing just
* so we can fix these 3 bits. Memory allocated by ep_tvb_memdup() is
* automatically freed before the next packet is processed.
*/
#ifdef HAVE_LIBGCRYPT
enc_buffer = (guint8 *)ep_tvb_memdup(tvb, 0, tvb_length(tvb));
/*
* Override the const qualifiers and patch the security level field, we
* know it is safe to overide the const qualifiers because we just
* allocated this memory via ep_tvb_memdup().
*/
enc_buffer[offset] = packet.control;
#endif /* HAVE_LIBGCRYPT */
packet.level = zbee_get_bit_field(packet.control, ZBEE_SEC_CONTROL_LEVEL);
packet.key_id = zbee_get_bit_field(packet.control, ZBEE_SEC_CONTROL_KEY);
packet.nonce = zbee_get_bit_field(packet.control, ZBEE_SEC_CONTROL_NONCE);
if (tree) {
ti = proto_tree_add_text(sec_tree, tvb, offset, 1, "Security Control Field");
field_tree = proto_item_add_subtree(ti, ett_zbee_sec_control);
proto_tree_add_uint(field_tree, hf_zbee_sec_key_id, tvb, offset, 1,
packet.control & ZBEE_SEC_CONTROL_KEY);
proto_tree_add_boolean(field_tree, hf_zbee_sec_nonce, tvb, offset, 1,
packet.control & ZBEE_SEC_CONTROL_NONCE);
}
offset += 1;
/* Get and display the frame counter field. */
packet.counter = tvb_get_letohl(tvb, offset);
if (tree) {
proto_tree_add_uint(sec_tree, hf_zbee_sec_counter, tvb, offset, 4, packet.counter);
}
offset += 4;
if (packet.nonce) {
/* Get and display the source address of the device that secured this payload. */
packet.src64 = tvb_get_letoh64(tvb, offset);
if (tree) {
proto_tree_add_item(sec_tree, hf_zbee_sec_src64, tvb, offset, 8, ENC_LITTLE_ENDIAN);
}
#if 1
if (!pinfo->fd->flags.visited) {
switch ( packet.key_id ) {
case ZBEE_SEC_KEY_LINK:
if (nwk_hints) {
/* Map this long address with the nwk layer short address. */
nwk_hints->map_rec = ieee802154_addr_update(&zbee_nwk_map, nwk_hints->src,
ieee_hints->src_pan, packet.src64, pinfo->current_proto, pinfo->fd->num);
}
break;
case ZBEE_SEC_KEY_NWK:
if (ieee_hints) {
/* Map this long address with the ieee short address. */
ieee_hints->map_rec = ieee802154_addr_update(&zbee_nwk_map, ieee_hints->src16,
ieee_hints->src_pan, packet.src64, pinfo->current_proto, pinfo->fd->num);
}
break;
/* We ignore the extended source addresses used to encrypt payloads with these
* types of keys, because they can emerge from APS tunnels created by nodes whose
* short address is not recorded in the packet. */
case ZBEE_SEC_KEY_TRANSPORT:
case ZBEE_SEC_KEY_LOAD:
break;
}
}
#endif
offset += 8;
}
else {
/* Look for a source address in hints */
switch ( packet.key_id ) {
case ZBEE_SEC_KEY_NWK:
/* use the ieee extended source address for NWK decryption */
if ( ieee_hints && (map_rec = ieee_hints->map_rec) ) packet.src64 = map_rec->addr64;
else if (tree) proto_tree_add_text(sec_tree, tvb, 0, 0, "[Extended Source: Unknown]");
break;
default:
/* use the nwk extended source address for APS decryption */
if ( nwk_hints && (map_rec = nwk_hints->map_rec) ) packet.src64 = map_rec->addr64;
else if (tree) proto_tree_add_text(sec_tree, tvb, 0, 0, "[Extended Source: Unknown]");
break;
}
}
if (packet.key_id == ZBEE_SEC_KEY_NWK) {
/* Get and display the key sequence number. */
packet.key_seqno = tvb_get_guint8(tvb, offset);
if (tree) {
proto_tree_add_uint(sec_tree, hf_zbee_sec_key_seqno, tvb, offset, 1, packet.key_seqno);
}
offset += 1;
}
/* Determine the length of the MIC. */
switch (packet.level) {
case ZBEE_SEC_ENC:
case ZBEE_SEC_NONE:
default:
mic_len=0;
break;
case ZBEE_SEC_ENC_MIC32:
case ZBEE_SEC_MIC32:
mic_len=4;
break;
case ZBEE_SEC_ENC_MIC64:
case ZBEE_SEC_MIC64:
mic_len=8;
break;
case ZBEE_SEC_ENC_MIC128:
case ZBEE_SEC_MIC128:
mic_len=16;
break;
} /* switch */
/* Get and display the MIC. */
if (mic_len) {
/* Display the MIC. */
if (tree) {
proto_tree_add_item(sec_tree, hf_zbee_sec_mic, tvb, (gint)(tvb_length(tvb)-mic_len),
mic_len, ENC_NA);
}
}
/* Check for null payload. */
if ( !(payload_len = tvb_reported_length_remaining(tvb, offset+mic_len)) ) {
return NULL;
} else if ( payload_len < 0 ) {
THROW(ReportedBoundsError);
}
/**********************************************
* Perform Security Operations on the Frame *
**********************************************
*/
if ((packet.level == ZBEE_SEC_NONE) ||
(packet.level == ZBEE_SEC_MIC32) ||
(packet.level == ZBEE_SEC_MIC64) ||
(packet.level == ZBEE_SEC_MIC128)) {
/* Payload is only integrity protected. Just return the sub-tvbuff. */
return tvb_new_subset(tvb, offset, payload_len, payload_len);
}
#ifdef HAVE_LIBGCRYPT
/* Allocate memory to decrypt the payload into. */
dec_buffer = (guint8 *)g_malloc(payload_len);
decrypted = FALSE;
if ( packet.src64 ) {
if (pinfo->fd->flags.visited) {
if ( nwk_hints ) {
/* Use previously found key */
switch ( packet.key_id ) {
case ZBEE_SEC_KEY_NWK:
if ( (key_rec = nwk_hints->nwk) ) {
decrypted = zbee_sec_decrypt_payload( &packet, enc_buffer, offset, dec_buffer,
payload_len, mic_len, nwk_hints->nwk->key);
}
break;
default:
if ( (key_rec = nwk_hints->link) ) {
decrypted = zbee_sec_decrypt_payload( &packet, enc_buffer, offset, dec_buffer,
payload_len, mic_len, nwk_hints->link->key);
}
break;
}
}
} /* ( !pinfo->fd->flags.visited ) */
else {
/* We only search for sniffed keys in the first pass,
* to save time, and because decrypting with keys
* transported in future packets is cheating */
/* Lookup NWK and link key in hash for this pan. */
/* This overkill approach is a placeholder for a hash that looks up
* a key ring for a link key associated with a pair of devices.
*/
if ( nwk_hints ) {
nwk_keyring = (GSList **)g_hash_table_lookup(zbee_table_nwk_keyring, &nwk_hints->src_pan);
if ( nwk_keyring ) {
GSList_i = *nwk_keyring;
while ( GSList_i && !decrypted ) {
decrypted = zbee_sec_decrypt_payload( &packet, enc_buffer, offset, dec_buffer,
payload_len, mic_len, ((key_record_t *)(GSList_i->data))->key);
if (decrypted) {
/* save pointer to the successful key record */
switch (packet.key_id) {
case ZBEE_SEC_KEY_NWK:
key_rec = nwk_hints->nwk = (key_record_t *)(GSList_i->data);
break;
default:
key_rec = nwk_hints->link = (key_record_t *)(GSList_i->data);
break;
}
} else {
GSList_i = g_slist_next(GSList_i);
}
}
}
/* Loop through user's password table for preconfigured keys, our last resort */
GSList_i = zbee_pc_keyring;
while ( GSList_i && !decrypted ) {
decrypted = zbee_sec_decrypt_payload( &packet, enc_buffer, offset, dec_buffer,
payload_len, mic_len, ((key_record_t *)(GSList_i->data))->key);
if (decrypted) {
/* save pointer to the successful key record */
switch (packet.key_id) {
case ZBEE_SEC_KEY_NWK:
key_rec = nwk_hints->nwk = (key_record_t *)(GSList_i->data);
break;
default:
key_rec = nwk_hints->link = (key_record_t *)(GSList_i->data);
break;
}
} else {
GSList_i = g_slist_next(GSList_i);
}
}
}
} /* ( ! pinfo->fd->flags.visited ) */
} /* ( packet.src64 ) */
if ( decrypted ) {
if ( tree && key_rec ) {
if ( key_rec->frame_num == ZBEE_SEC_PC_KEY ) {
ti = proto_tree_add_text(sec_tree, tvb, 0, 0, "Decryption Key: %s", key_rec->label);
} else {
ti = proto_tree_add_uint(sec_tree, hf_zbee_sec_key_origin, tvb, 0, 0,
key_rec->frame_num);
}
PROTO_ITEM_SET_GENERATED(ti);
}
/* Found a key that worked, setup the new tvbuff_t and return */
payload_tvb = tvb_new_child_real_data(tvb, dec_buffer, payload_len, payload_len);
tvb_set_free_cb(payload_tvb, g_free); /* set up callback to free dec_buffer */
add_new_data_source(pinfo, payload_tvb, "Decrypted ZigBee Payload");
/* Done! */
return payload_tvb;
}
g_free(dec_buffer);
#endif /* HAVE_LIBGCRYPT */
/* Add expert info. */
expert_add_info_format(pinfo, sec_tree, PI_UNDECODED, PI_WARN, "Encrypted Payload");
/* Create a buffer for the undecrypted payload. */
payload_tvb = tvb_new_subset(tvb, offset, payload_len, -1);
/* Dump the payload to the data dissector. */
call_dissector(data_handle, payload_tvb, pinfo, tree);
/* Couldn't decrypt, so return NULL. */
return NULL;
} /* dissect_zbee_secure */
/*FUNCTION:------------------------------------------------------
* NAME
* dissect_zbee_secure
* DESCRIPTION
* Dissects and decrypts secured ZigBee frames.
*
* Will return a valid tvbuff only if security processing was
* successful. If processing fails, then this function will
* handle internally and return NULL.
* PARAMETERS
* tvbuff_t *tvb - pointer to buffer containing raw packet.
* packet_into *pinfo - pointer to packet information fields
* proto_tree *tree - pointer to data tree Wireshark uses to display packet.
* guint offset - pointer to the start of the auxilliary security header.
* guint64 src - extended source address, or 0 if unknown.
* RETURNS
* tvbuff_t *
*---------------------------------------------------------------
*/
tvbuff_t *
dissect_zbee_secure(tvbuff_t *tvb, packet_info *pinfo, proto_tree* tree, guint offset, guint64 src)
{
proto_tree * sec_tree = NULL;
proto_item * sec_root;
proto_tree * field_tree;
proto_item * ti;
zbee_security_packet packet;
guint mic_len;
guint payload_len;
tvbuff_t * payload_tvb;
#ifdef HAVE_LIBGCRYPT
const guint8 * enc_buffer;
guint8 * dec_buffer;
guint8 * key_buffer;
guint8 nonce[ZBEE_SEC_CONST_NONCE_LEN];
#endif
/* Create a substree for the security information. */
if (tree) {
sec_root = proto_tree_add_text(tree, tvb, offset, tvb_length_remaining(tvb, offset), "ZigBee Security Header");
sec_tree = proto_item_add_subtree(sec_root, ett_zbee_sec);
}
/* Get and display the Security control field */
packet.control = tvb_get_guint8(tvb, offset);
/* Patch the security level. */
packet.control &= ~ZBEE_SEC_CONTROL_LEVEL;
packet.control |= (ZBEE_SEC_CONTROL_LEVEL & gPREF_zbee_sec_level);
/*
* Eww, I think I just threw up a little... ZigBee requires this field
* to be patched before computing the MIC, but we don't have write-access
* to the tvbuff. So we need to allocate a copy of the whole thing just
* so we can fix these 3 bits.
*/
#ifdef HAVE_LIBGCRYPT
enc_buffer = ep_tvb_memdup(tvb, 0, tvb_length(tvb));
/*
* Override the const qualifiers and patch the security level field, we
* know it is safe to overide the const qualifiers because we just
* allocated this memory via ep_tvb_memdup().
*/
((guint8 *)(enc_buffer))[offset] = packet.control;
#endif /* HAVE_LIBGCRYPT */
packet.level = zbee_get_bit_field(packet.control, ZBEE_SEC_CONTROL_LEVEL);
packet.key = zbee_get_bit_field(packet.control, ZBEE_SEC_CONTROL_KEY);
packet.nonce = zbee_get_bit_field(packet.control, ZBEE_SEC_CONTROL_NONCE);
if (tree) {
ti = proto_tree_add_text(sec_tree, tvb, offset, sizeof(guint8), "Security Control Field");
field_tree = proto_item_add_subtree(ti, ett_zbee_sec_control);
proto_tree_add_uint(field_tree, hf_zbee_sec_key, tvb, offset, sizeof(guint8), packet.control & ZBEE_SEC_CONTROL_KEY);
proto_tree_add_boolean(field_tree, hf_zbee_sec_nonce, tvb, offset, sizeof(guint8), packet.control & ZBEE_SEC_CONTROL_NONCE);
}
offset += sizeof(guint8);
/* Get and display the frame counter field. */
packet.counter = tvb_get_letohl(tvb, offset);
if (tree) {
proto_tree_add_uint(sec_tree, hf_zbee_sec_counter, tvb, offset, sizeof(guint32), packet.counter);
}
offset += sizeof(guint32);
if (packet.nonce) {
/* Get and display the source address. */
packet.src = tvb_get_letoh64(tvb, offset);
if (tree) {
proto_tree_add_eui64(sec_tree, hf_zbee_sec_src, tvb, offset, sizeof(guint64), packet.src);
}
offset += sizeof(guint64);
}
else {
/* This field is required in the security decryption process, so
* fill it in in case the higher layer provided it.
*/
packet.src = src;
}
if (packet.key == ZBEE_SEC_KEY_NWK) {
/* Get and display the key sequence number. */
packet.key_seqno = tvb_get_guint8(tvb, offset);
if (tree) {
proto_tree_add_uint(sec_tree, hf_zbee_sec_key_seqno, tvb, offset, sizeof(guint8), packet.key_seqno);
}
offset += sizeof(guint8);
}
/* Determine the length of the MIC. */
switch (packet.level){
case ZBEE_SEC_ENC:
case ZBEE_SEC_NONE:
default:
mic_len=0;
break;
case ZBEE_SEC_ENC_MIC32:
case ZBEE_SEC_MIC32:
mic_len=4;
break;
case ZBEE_SEC_ENC_MIC64:
case ZBEE_SEC_MIC64:
mic_len=8;
break;
case ZBEE_SEC_ENC_MIC128:
case ZBEE_SEC_MIC128:
mic_len=16;
break;
} /* switch */
/* Ensure that the payload exists (length >= 1) for this length. */
payload_len = tvb_ensure_length_remaining(tvb, offset+mic_len+1)+1;
/* Get and display the MIC. */
if (mic_len) {
/* Display the MIC. */
if (tree) {
ti = proto_tree_add_bytes(sec_tree, hf_zbee_sec_mic, tvb, tvb_length(tvb)-mic_len, mic_len, ep_tvb_memdup(tvb, tvb_length(tvb)-mic_len, mic_len));
}
}
/**********************************************
* Perform Security Operations on the Frame *
**********************************************
*/
if ((packet.level == ZBEE_SEC_NONE) ||
(packet.level == ZBEE_SEC_MIC32) ||
(packet.level == ZBEE_SEC_MIC64) ||
(packet.level == ZBEE_SEC_MIC128)) {
/* Payload is only integrity protected. Just return the sub-tvbuff. */
return tvb_new_subset(tvb, offset, payload_len, payload_len);
}
#ifdef HAVE_LIBGCRYPT
/* Ensure we have enough security material to decrypt this payload. */
switch (packet.key) {
/* Network Keys use the shared network key. */
case ZBEE_SEC_KEY_NWK:
if (!zbee_sec_have_nwk_key) {
/* Without a key we can't decrypt (if we could what good would security be?)*/
goto decrypt_failed;
}
if (packet.src == 0) {
/* Without the extended source address, we can't create the nonce. */
goto decrypt_failed;
}
/* The key, is the network key. */
key_buffer = zbee_sec_nwk_key;
break;
/* Link Key might use the trust center link key. */
case ZBEE_SEC_KEY_LINK:
if (!zbee_sec_have_tclink_key) {
/* Without a key we can't decrypt. */
goto decrypt_failed;
}
if ((packet.src == 0) && (zbee_sec_tcaddr == 0)){
/* Without the extended source address, we can't create the nonce. */
goto decrypt_failed;
}
else if (packet.src == 0) {
packet.src = zbee_sec_tcaddr;
}
key_buffer = zbee_sec_tclink_key;
break;
/* Key-Transport Key should use the trust center link key. */
case ZBEE_SEC_KEY_TRANSPORT:
if (!zbee_sec_have_tclink_key) {
/* Without a key we can't decrypt. */
goto decrypt_failed;
}
if ((packet.src == 0) && (zbee_sec_tcaddr == 0)){
/* Without the extended source address, we can't create the nonce. */
goto decrypt_failed;
}
else if (packet.src == 0) {
packet.src = zbee_sec_tcaddr;
}
key_buffer = zbee_sec_key_hash(zbee_sec_tclink_key, 0x00, pinfo);
break;
/* Key-Load Key should use the trust center link key. */
case ZBEE_SEC_KEY_LOAD:
if (!zbee_sec_have_tclink_key) {
/* Without a key we can't decrypt. */
goto decrypt_failed;
}
if ((packet.src == 0) && (zbee_sec_tcaddr == 0)){
/* Without the extended source address, we can't create the nonce. */
goto decrypt_failed;
}
else if (packet.src == 0) {
packet.src = zbee_sec_tcaddr;
}
key_buffer = zbee_sec_key_hash(zbee_sec_tclink_key, 0x02, pinfo);
break;
default:
goto decrypt_failed;
} /* switch */
/* Create the nonce. */
zbee_sec_make_nonce(nonce, &packet);
/* Allocate memory to decrypt the payload into. */
dec_buffer = g_malloc(payload_len);
/* Perform Decryption. */
if (!zbee_sec_ccm_decrypt(key_buffer, /* key */
nonce, /* Nonce */
enc_buffer, /* a, length l(a) */
enc_buffer+offset, /* c, length l(c) = l(m) + M */
dec_buffer, /* m, length l(m) */
offset, /* l(a) */
payload_len, /* l(m) */
mic_len)) { /* M */
/* Decryption Failed! */
g_free(dec_buffer);
goto decrypt_failed;
}
/* Setup the new tvbuff_t and return */
payload_tvb = tvb_new_child_real_data(tvb, dec_buffer, payload_len, payload_len);
add_new_data_source(pinfo, payload_tvb, "Decrypted ZigBee Payload");
/* Done! */
return payload_tvb;
decrypt_failed:
#endif /* HAVE_LIBGCRYPT */
/* Add expert info. */
expert_add_info_format(pinfo, sec_tree, PI_UNDECODED, PI_WARN, "Encrypted Payload");
/* Create a buffer for the undecrypted payload. */
payload_tvb = tvb_new_subset(tvb, offset, payload_len, -1);
/* Dump the payload to the data dissector. */
call_dissector(data_handle, payload_tvb, pinfo, tree);
/* Couldn't decrypt, so return NULL. */
return NULL;
} /* dissect_zbee_secure */
