linux-kernel - [PATCH 3.16 118/158] Bluetooth: Fix tracking local SSP authentication requirement

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Date:	Mon, 15 Sep 2014 12:25:57 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Johan Hedberg <johan.hedberg@...el.com>,
	Szymon Janc <szymon.janc@...to.com>,
	Marcel Holtmann <marcel@...tmann.org>
Subject: [PATCH 3.16 118/158] Bluetooth: Fix tracking local SSP authentication requirement

3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit 6c53823ae0e10e723131055e1e65dd6a328a228e upstream.

When we need to make the decision whether to perform just-works or real
user confirmation we need to know the exact local authentication
requirement that was passed to the controller. So far conn->auth_type
(the local requirement) wasn't in one case updated appropriately in fear
of the user confirmation being rejected later.

The real problem however was not really that conn->auth_type couldn't
represent the true value but that we were checking the local MITM
requirement in an incorrect way. It's perfectly fine to let auth_type
follow what we tell the controller since we're still tracking the target
security level with conn->pending_sec_level.

This patch updates the check for local MITM requirement in the
hci_user_confirm_request_evt function to use the locally requested
security level and ensures that auth_type always represents what we tell
the controller. All other code in hci_user_confirm_request_evt still
uses the auth_type instead of pending_sec_level for determining whether
to do just-works or not, since that's the only value that's in sync with
what the remote device knows.

Signed-off-by: Johan Hedberg <johan.hedberg@...el.com>
Tested-by: Szymon Janc <szymon.janc@...to.com>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/bluetooth/hci_event.c |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3538,18 +3538,14 @@ static void hci_io_capa_request_evt(stru

 		/* If we are initiators, there is no remote information yet */
 		if (conn->remote_auth == 0xff) {
-			cp.authentication = conn->auth_type;
-
 			/* Request MITM protection if our IO caps allow it
 			 * except for the no-bonding case.
-			 * conn->auth_type is not updated here since
-			 * that might cause the user confirmation to be
-			 * rejected in case the remote doesn't have the
-			 * IO capabilities for MITM.
 			 */
 			if (conn->io_capability != HCI_IO_NO_INPUT_OUTPUT &&
 			    cp.authentication != HCI_AT_NO_BONDING)
-				cp.authentication |= 0x01;
+				conn->auth_type |= 0x01;
+
+			cp.authentication = conn->auth_type;
 		} else {
 			conn->auth_type = hci_get_auth_req(conn);
 			cp.authentication = conn->auth_type;
@@ -3621,9 +3617,12 @@ static void hci_user_confirm_request_evt
 	rem_mitm = (conn->remote_auth & 0x01);

 	/* If we require MITM but the remote device can't provide that
-	 * (it has NoInputNoOutput) then reject the confirmation request
+	 * (it has NoInputNoOutput) then reject the confirmation
+	 * request. We check the security level here since it doesn't
+	 * necessarily match conn->auth_type.
 	 */
-	if (loc_mitm && conn->remote_cap == HCI_IO_NO_INPUT_OUTPUT) {
+	if (conn->pending_sec_level > BT_SECURITY_MEDIUM &&
+	    conn->remote_cap == HCI_IO_NO_INPUT_OUTPUT) {
 		BT_DBG("Rejecting request: remote device can't provide MITM");
 		hci_send_cmd(hdev, HCI_OP_USER_CONFIRM_NEG_REPLY,
 			     sizeof(ev->bdaddr), &ev->bdaddr);

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