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;
--
2.19.1
