From: Bastien Nocera hadess@hadess.net

Bluetooth: L2CAP: Try harder to accept device not knowing options

The current implementation of L2CAP options negotiation will continue the negotiation when a device responds with L2CAP_CONF_UNACCEPT ("unaccepted options"), but not when the device replies with L2CAP_CONF_UNKNOWN ("unknown options").

Trying to continue the negotiation without ERTM support will allow Bluetooth-capable XBox One controllers (notably models 1708 and 1797) to connect.

btmon before patch:

ACL Data RX: Handle 256 flags 0x02 dlen 16 #64 [hci0] 59.182702

L2CAP: Connection Response (0x03) ident 2 len 8 Destination CID: 64 Source CID: 64 Result: Connection successful (0x0000) Status: No further information available (0x0000) < ACL Data TX: Handle 256 flags 0x00 dlen 23 #65 [hci0] 59.182744 L2CAP: Configure Request (0x04) ident 3 len 15 Destination CID: 64 Flags: 0x0000 Option: Retransmission and Flow Control (0x04) [mandatory] Mode: Basic (0x00) TX window size: 0 Max transmit: 0 Retransmission timeout: 0 Monitor timeout: 0 Maximum PDU size: 0

ACL Data RX: Handle 256 flags 0x02 dlen 16 #66 [hci0] 59.183948

L2CAP: Configure Request (0x04) ident 1 len 8 Destination CID: 64 Flags: 0x0000 Option: Maximum Transmission Unit (0x01) [mandatory] MTU: 1480 < ACL Data TX: Handle 256 flags 0x00 dlen 18 #67 [hci0] 59.183994 L2CAP: Configure Response (0x05) ident 1 len 10 Source CID: 64 Flags: 0x0000 Result: Success (0x0000) Option: Maximum Transmission Unit (0x01) [mandatory] MTU: 1480

ACL Data RX: Handle 256 flags 0x02 dlen 15 #69 [hci0] 59.187676

L2CAP: Configure Response (0x05) ident 3 len 7 Source CID: 64 Flags: 0x0000 Result: Failure - unknown options (0x0003) 04 . < ACL Data TX: Handle 256 flags 0x00 dlen 12 #70 [hci0] 59.187722 L2CAP: Disconnection Request (0x06) ident 4 len 4 Destination CID: 64 Source CID: 64

ACL Data RX: Handle 256 flags 0x02 dlen 12 #73 [hci0] 59.192714

L2CAP: Disconnection Response (0x07) ident 4 len 4 Destination CID: 64 Source CID: 64

btmon after patch:

ACL Data RX: Handle 256 flags 0x02 dlen 16 #248 [hci0] 103.502970

L2CAP: Connection Response (0x03) ident 5 len 8 Destination CID: 65 Source CID: 65 Result: Connection pending (0x0001) Status: No further information available (0x0000)

ACL Data RX: Handle 256 flags 0x02 dlen 16 #249 [hci0] 103.504184

L2CAP: Connection Response (0x03) ident 5 len 8 Destination CID: 65 Source CID: 65 Result: Connection successful (0x0000) Status: No further information available (0x0000) < ACL Data TX: Handle 256 flags 0x00 dlen 23 #250 [hci0] 103.504398 L2CAP: Configure Request (0x04) ident 6 len 15 Destination CID: 65 Flags: 0x0000 Option: Retransmission and Flow Control (0x04) [mandatory] Mode: Basic (0x00) TX window size: 0 Max transmit: 0 Retransmission timeout: 0 Monitor timeout: 0 Maximum PDU size: 0

ACL Data RX: Handle 256 flags 0x02 dlen 16 #251 [hci0] 103.505472

L2CAP: Configure Request (0x04) ident 3 len 8 Destination CID: 65 Flags: 0x0000 Option: Maximum Transmission Unit (0x01) [mandatory] MTU: 1480 < ACL Data TX: Handle 256 flags 0x00 dlen 18 #252 [hci0] 103.505689 L2CAP: Configure Response (0x05) ident 3 len 10 Source CID: 65 Flags: 0x0000 Result: Success (0x0000) Option: Maximum Transmission Unit (0x01) [mandatory] MTU: 1480

ACL Data RX: Handle 256 flags 0x02 dlen 15 #254 [hci0] 103.509165

L2CAP: Configure Response (0x05) ident 6 len 7 Source CID: 65 Flags: 0x0000 Result: Failure - unknown options (0x0003) 04 . < ACL Data TX: Handle 256 flags 0x00 dlen 12 #255 [hci0] 103.509426 L2CAP: Configure Request (0x04) ident 7 len 4 Destination CID: 65 Flags: 0x0000 < ACL Data TX: Handle 256 flags 0x00 dlen 12 #257 [hci0] 103.511870 L2CAP: Connection Request (0x02) ident 8 len 4 PSM: 1 (0x0001) Source CID: 66

ACL Data RX: Handle 256 flags 0x02 dlen 14 #259 [hci0] 103.514121

L2CAP: Configure Response (0x05) ident 7 len 6 Source CID: 65 Flags: 0x0000 Result: Success (0x0000)

Upstream Status: bluetooth/bluetooth-next.git (cherry picked from commit 98d2c3e1731007acf03addf83c863df6694beb95)

Signed-off-by: Bastien Nocera hadess@hadess.net Signed-off-by: Florian Dollinger dollinger.florian@gmx.de Co-developed-by: Florian Dollinger dollinger.florian@gmx.de Reviewed-by: Luiz Augusto Von Dentz luiz.von.dentz@intel.com Signed-off-by: Marcel Holtmann marcel@holtmann.org

diff a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -4519,6 +4519,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, } goto done;

+ case L2CAP_CONF_UNKNOWN: case L2CAP_CONF_UNACCEPT: if (chan->num_conf_rsp <= L2CAP_CONF_MAX_CONF_RSP) { char req[64];

-- https://gitlab.com/cki-project/kernel-ark/-/merge_requests/872