[OS-BUILD PATCH] Bluetooth: L2CAP: Try harder to accept device not knowing options

[Bastien Nocera (via Email Bridge)]

From: Bastien Nocera <hadess(a)hadess.net&gt;

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(a)hadess.net&gt;
Signed-off-by: Florian Dollinger <dollinger.florian(a)gmx.de&gt;
Co-developed-by: Florian Dollinger <dollinger.florian(a)gmx.de&gt;
Reviewed-by: Luiz Augusto Von Dentz <luiz.von.dentz(a)intel.com&gt;
Signed-off-by: Marcel Holtmann <marcel(a)holtmann.org&gt;

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