[PATCH 4/5] Bluetooth: Re-encrypt link after receiving an LTK

[johan.hedberg@gmail.com]

From: Johan Hedberg <johan.hedberg@intel.com>

It's not strictly speaking required to re-encrypt a link once we receive
an LTK since the connection is already encrypted with the STK. However,
re-encrypting with the LTK allows us to verify that we've received an
LTK that actually works.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
---
 net/bluetooth/smp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 0de98fe23330..52708f79545f 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -1268,6 +1268,13 @@ int smp_distribute_keys(struct l2cap_conn *conn)
 	set_bit(SMP_FLAG_COMPLETE, &smp->smp_flags);
 	smp_notify_keys(conn);
 
+	/* Re-encrypt the link with LTK */
+	if (smp->ltk) {
+		struct smp_ltk *ltk = smp->ltk;
+		hci_le_start_enc(hcon, ltk->ediv, ltk->rand, ltk->val);
+		hcon->enc_key_size = ltk->enc_size;
+	}
+
 	smp_chan_destroy(conn);
 
 	return 0;
-- 
1.8.5.3