Commit 545d7827 authored by Luiz Augusto von Dentz's avatar Luiz Augusto von Dentz
Browse files

Bluetooth: SMP: Fix not generating mackey and ltk when repairing 

The change eed467b5 ("Bluetooth: fix passkey uninitialized when used")
introduced a goto that bypasses the creation of temporary mackey and ltk
which are later used by the likes of DHKey Check step.

Later ffee202a ("Bluetooth: Always request for user confirmation for
Just Works (LE SC)") which means confirm_hint is always set in case
JUST_WORKS so the branch checking for an existing LTK becomes pointless
as confirm_hint will always be set, so this just merge both cases of
malicious or legitimate devices to be confirmed before continuing with the
pairing procedure.

Link: https://github.com/bluez/bluez/issues/1622


Fixes: eed467b5 ("Bluetooth: fix passkey uninitialized when used")
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
parent c884a0b2

net/bluetooth/smp.c

+7 −24
Original line number Diff line number Diff line
@@ -2136,7 +2136,7 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) 
	struct smp_chan *smp = chan->data;

	struct hci_conn *hcon = conn->hcon;

	u8 *pkax, *pkbx, *na, *nb, confirm_hint;

	u32 passkey;

	u32 passkey = 0;

	int err;



	bt_dev_dbg(hcon->hdev, "conn %p", conn);
@@ -2188,24 +2188,6 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) 
		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),

			     smp->prnd);

		SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);



		/* Only Just-Works pairing requires extra checks */

		if (smp->method != JUST_WORKS)

			goto mackey_and_ltk;



		/* If there already exists long term key in local host, leave

		 * the decision to user space since the remote device could

		 * be legitimate or malicious.

		 */

		if (hci_find_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,

				 hcon->role)) {

			/* Set passkey to 0. The value can be any number since

			 * it'll be ignored anyway.

			 */

			passkey = 0;

			confirm_hint = 1;

			goto confirm;

		}

	}



mackey_and_ltk:
@@ -2226,11 +2208,12 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) 
	if (err)

		return SMP_UNSPECIFIED;



	confirm_hint = 0;



confirm:

	if (smp->method == JUST_WORKS)

		confirm_hint = 1;

	/* Always require user confirmation for Just-Works pairing to prevent

	 * impersonation attacks, or in case of a legitimate device that is

	 * repairing use the confirmation as acknowledgment to proceed with the

	 * creation of new keys.

	 */

	confirm_hint = smp->method == JUST_WORKS ? 1 : 0;



	err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst, hcon->type,

					hcon->dst_type, passkey, confirm_hint);