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)
Signed-off-by: Florian Dollinger <dollinger.florian@xxxxxx>
Co-developed-by: Florian Dollinger <dollinger.florian@xxxxxx>
---
net/bluetooth/l2cap_core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 1ab27b90ddcb..3ab95ea2cd80 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4513,6 +4513,7 @@ 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];
--
2.29.2
