[PATCH BlueZ v2] mesh: Honor IV Update flag in app layer crypto

[PATCH BlueZ v2] mesh: Honor IV Update flag in app layer crypto

[Michał Lowas-Rzechonek]

Since IV Index is used in application nonces, we need to honor IV Update
flag not only in network layer crypto, but also in application layer.
Otherwise, we cannot decode application payloads from nodes that are in
IV Update state.
---
 mesh/net-keys.c |  6 ------
 mesh/net.c      | 20 +++++++++++---------
 2 files changed, 11 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..12971a179 100644
--- a/mesh/net.c
+++ b/mesh/net.c
@@ -2489,8 +2489,16 @@ static void net_rx(void *net_ptr, void *user_data)
 	size_t out_size;
 	uint32_t key_id;
 	int8_t rssi = 0;
+	uint32_t iv_index;
+	bool iv_flag = !!(net->iv_index & 1);
+	bool iv_pkt = !!(data->data[0] & 0x80);
+
+	if (iv_pkt == iv_flag)
+		iv_index = net->iv_index;
+	else
+		iv_index = net->iv_index - 1;
 
-	key_id = net_key_decrypt(net->iv_index, data->data, data->len,
+	key_id = net_key_decrypt(iv_index, data->data, data->len,
 							&out, &out_size);
 
 	if (!key_id)
@@ -2504,16 +2512,10 @@ 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