Bluetooth: Fix incorrect SSP mode bit for non SSP devices

Some faulty non SSP devices send extended inquiry response
during device discovery which is a violation of 2.1 specification.
So for these devices we set SSP bit during acl connection
initiation thinking that it is an SSP device. But for these
devices, in remote host features event SSP supported bit
will be off. But we are not clearing the SSP bit in that case
and eventually SSP bit in conn flag will be incorrectly set for
these devices.

The software which has caused this issue is MecApp
http://www.mecel.se/products/bluetooth/downloads/MecApp_download

This patch does a workaround by clearing the SSP bit if it is
not supported in remote host features event

hcidump log
----------

< HCI Command: Inquiry (0x01|0x0001) plen 5
    lap 0x9e8b33 len 4 num 0
> HCI Event: Command Status (0x0f) plen 4
    Inquiry (0x01|0x0001) status 0x00 ncmd 1
> HCI Event: Extended Inquiry Result (0x2f) plen 255
    bdaddr 00:1B:DC:05:B5:25 mode 1 clkoffset 0x3263 class 0x3c0000 rssi -77
    Unknown type 0x42 with 8 bytes data
    Unknown type 0x1e with 2 bytes data
> HCI Event: Inquiry Complete (0x01) plen 1
    status 0x00

< HCI Command: Create Connection (0x01|0x0005) plen 13
    bdaddr 00:1B:DC:05:B5:25 ptype 0xcc18 rswitch 0x01 clkoffset 0x0000
    Packet type: DM1 DM3 DM5 DH1 DH3 DH5
> HCI Event: Command Status (0x0f) plen 4
    Create Connection (0x01|0x0005) status 0x00 ncmd 1
> HCI Event: Connect Complete (0x03) plen 11
    status 0x00 handle 12 bdaddr 00:1B:DC:05:B5:25 type ACL encrypt 0x00
< HCI Command: Read Remote Supported Features (0x01|0x001b) plen 2
    handle 12
> HCI Event: Command Status (0x0f) plen 4
    Read Remote Supported Features (0x01|0x001b) status 0x00 ncmd 1
> HCI Event: Read Remote Supported Features (0x0b) plen 11
    status 0x00 handle 12
    Features: 0xff 0xff 0x8f 0x7e 0xd8 0x1f 0x5b 0x87
< HCI Command: Read Remote Extended Features (0x01|0x001c) plen 3
    handle 12 page 1
> HCI Event: Command Status (0x0f) plen 4
    Read Remote Extended Features (0x01|0x001c) status 0x00 ncmd 1
> HCI Event: Page Scan Repetition Mode Change (0x20) plen 7
    bdaddr 00:1B:DC:05:B5:25 mode 1
> HCI Event: Max Slots Change (0x1b) plen 3
    handle 12 slots 5
> HCI Event: Read Remote Extended Features (0x23) plen 13
    status 0x00 handle 12 page 1 max 0
    Features: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
< HCI Command: Remote Name Request (0x01|0x0019) plen 10
    bdaddr 00:1B:DC:05:B5:25 mode 2 clkoffset 0x0000
> HCI Event: Command Status (0x0f) plen 4
    Remote Name Request (0x01|0x0019) status 0x00 ncmd 1
> HCI Event: Remote Name Req Complete (0x07) plen 255
    status 0x00 bdaddr 00:1B:DC:05:B5:25 name 'Bluetooth PTS Radio v4'
< HCI Command: Authentication Requested (0x01|0x0011) plen 2
    handle 12
> HCI Event: Command Status (0x0f) plen 4
    Authentication Requested (0x01|0x0011) status 0x00 ncmd 1
> HCI Event: Link Key Request (0x17) plen 6
    bdaddr 00:1B:DC:05:B5:25
< HCI Command: Link Key Request Negative Reply (0x01|0x000c) plen 6
    bdaddr 00:1B:DC:05:B5:25
> HCI Event: Command Complete (0x0e) plen 10
    Link Key Request Negative Reply (0x01|0x000c) ncmd 1
    status 0x00 bdaddr 00:1B:DC:05:B5:25
> HCI Event: PIN Code Request (0x16) plen 6
    bdaddr 00:1B:DC:05:B5:25

Signed-off-by: Jaganath Kanakkassery <jaganath.k@samsung.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

1 files changed, 12 insertions, 1 deletions

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 688c1a9..6fa9090 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -2931,8 +2931,19 @@ static void hci_remote_ext_features_evt(struct hci_dev *hdev,
 		if (ie)
 			ie->data.ssp_mode = (ev->features[0] & LMP_HOST_SSP);
 
-		if (ev->features[0] & LMP_HOST_SSP)
+		if (ev->features[0] & LMP_HOST_SSP) {
 			set_bit(HCI_CONN_SSP_ENABLED, &conn->flags);
+		} else {
+			/* It is mandatory by the Bluetooth specification that
+			 * Extended Inquiry Results are only used when Secure
+			 * Simple Pairing is enabled, but some devices violate
+			 * this.
+			 *
+			 * To make these devices work, the internal SSP
+			 * enabled flag needs to be cleared if the remote host
+			 * features do not indicate SSP support */
+			clear_bit(HCI_CONN_SSP_ENABLED, &conn->flags);
+		}
 	}
 
 	if (conn->state != BT_CONFIG)