Re: [PATCH BlueZ v3 1/2] mesh: Fixed handling of IVI flag in app layer

["Gix, Brian" <brian.gix@intel.com>]

Patch applied, Thanks.


On Thu, 2019-06-27 at 09:40 +0200, Michał Lowas-Rzechonek wrote:
> Since IV Index is used in application nonces, we need to honor IVI flag
> not only in network layer crypto, but also in application layer.
> 
> This means that if IVI field of incoming packet is different than in
> current IV Index, try to decode *both* net and app layers using IV Index
> decreased by one.
> ---
>  mesh/net-keys.c |  6 ------
>  mesh/net.c      | 17 ++++++++---------
>  2 files changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/mesh/net-keys.c b/mesh/net-keys.c
> index 25f4caeb7..5be7e0b58 100644
> --- a/mesh/net-keys.c
> +++ b/mesh/net-keys.c
> @@ -209,12 +209,6 @@ static void decrypt_net_pkt(void *a, void *b)
>  uint32_t net_key_decrypt(uint32_t iv_index, const uint8_t *pkt, size_t len,
>  					uint8_t **plain, size_t *plain_len)
>  {
> -	bool iv_flag = !!(iv_index & 1);
> -	bool iv_pkt = !!(pkt[0] & 0x80);
> -
> -	if (iv_pkt != iv_flag)
> -		iv_index--;
> -
>  	/* If we already successfully decrypted this packet, use cached data */
>  	if (cache_id && cache_len == len && !memcmp(pkt, cache_pkt, len)) {
>  		/* IV Index must match what was used to decrypt */
> diff --git a/mesh/net.c b/mesh/net.c
> index a597b8794..a5693f154 100644
> --- a/mesh/net.c
> +++ b/mesh/net.c
> @@ -2489,8 +2489,13 @@ static void net_rx(void *net_ptr, void *user_data)
>  	size_t out_size;
>  	uint32_t key_id;
>  	int8_t rssi = 0;
> +	bool ivi_net = !!(net->iv_index & 1);
> +	bool ivi_pkt = !!(data->data[0] & 0x80);
>  
> -	key_id = net_key_decrypt(net->iv_index, data->data, data->len,
> +	/* if IVI flag differs, use previous IV Index */
> +	uint32_t iv_index = net->iv_index - (ivi_pkt ^ ivi_net);
> +
> +	key_id = net_key_decrypt(iv_index, data->data, data->len,
>  							&out, &out_size);
>  
>  	if (!key_id)
> @@ -2504,16 +2509,10 @@ static void net_rx(void *net_ptr, void *user_data)
>  		rssi = data->info->rssi;
>  	}
>  
> -	relay_advice = packet_received(net, key_id, net->iv_index,
> +	relay_advice = packet_received(net, key_id, iv_index,
>  							out, out_size, rssi);
>  	if (relay_advice > data->relay_advice) {
> -		bool iv_flag = !!(net->iv_index & 1);
> -		bool iv_pkt = !!(data->data[0] & 0x80);
> -
> -		data->iv_index = net->iv_index;
> -		if (iv_pkt != iv_flag)
> -			data->iv_index--;
> -
> +		data->iv_index = iv_index;
>  		data->relay_advice = relay_advice;
>  		data->key_id = key_id;
>  		data->net = net;