Hi Luiz,
> On Thu, Jul 6, 2023 at 7:46 PM Xigang(Ted) Feng
> <Xigang.Feng@xxxxxxxxxxxxx> wrote:
> >
> > This test case is for verifying the L2CAP signalling PDUs that have invalid length
> are properly handled.
> > With this patch, the "L2CAP: Command Reject" packet is sent correctly to the
> malformed signal packet
> > contained in "L2CAP: Connection Request" packet.
> >
> > BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 3, Part A page 1041
> >
> > 'When a packet is received with a Code field that is unknown or disallowed on
> the
> > signalling channel it is received on, an L2CAP_COMMAND_REJECT_RSP
> > packet (defined in Section 4.1) is sent in response.'
> >
> > Before this patch:
> >
> > > ACL Data RX: Handle 1 flags 0x02 dlen 15
> > L2CAP: Connection Request (0x02) ident 3 len 4
> > PSM: 1 (0x0001)
> > Source CID: 64
> > malformed signal packet
> > 00 00 00 ...
> > < ACL Data TX: Handle 1 flags 0x00 dlen 16
> > L2CAP: Connection Response (0x03) ident 3 len 8
> > Destination CID: 64
> > Source CID: 64
> > Result: Connection successful (0x0000)
> > Status: No further information available (0x0000)
> > < ACL Data TX: Handle 1 flags 0x00 dlen 23
> > 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
> > > HCI Event: Number of Completed Packets (0x13) plen 5
> > Num handles: 1
> > Handle: 1
> > Count: 2
> > > ACL Data RX: Handle 1 flags 0x02 dlen 25
> > L2CAP: Configure Response (0x05) ident 3 len 17
> > Source CID: 64
> > Flags: 0x0000
> > Result: Success (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 TX: Handle 1 flags 0x00 dlen 12
> > L2CAP: Disconnection Request (0x06) ident 4 len 4
> > Destination CID: 64
> > Source CID: 64
> > > HCI Event: Number of Completed Packets (0x13) plen 5
> > Num handles: 1
> > Handle: 1
> > Count: 1
> > > ACL Data RX: Handle 1 flags 0x02 dlen 12
> > L2CAP: Disconnection Response (0x07) ident 4 len 4
> > Destination CID: 64
> > Source CID: 64
> > < HCI Command: Disconnect (0x01|0x0006) plen 3
> > Handle: 1
> > Reason: Remote User Terminated Connection (0x13)
> >
> > After this patch:
> >
> > > ACL Data RX: Handle 1 flags 0x02 dlen 15
> > L2CAP: Connection Request (0x02) ident 3 len 4
> > PSM: 4113 (0x1011)
> > Source CID: 64
> > malformed signal packet
> > 00 00 00 ...
> > < ACL Data TX: Handle 1 flags 0x00 dlen 16
> > L2CAP: Connection Response (0x03) ident 3 len 8
> > Destination CID: 64
> > Source CID: 64
> > Result: Connection successful (0x0000)
> > Status: No further information available (0x0000)
> > < ACL Data TX: Handle 1 flags 0x00 dlen 23
> > 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
>
> Looks like we are still sending a Configure Request which is sort of
> useless if we are sending a Reject in the follow up command.
I'm following the test case "L2CAP/COS/CED/BI-02-C" in " L2CAP Test Suite" from Bluetooth SIG.
In Test Procedure, step 3 sends a L2CAP_CONNECTION_REQ with three extra bytes of 0.
Step 4 sends back L2CAP_CONNECTION_RSP to indicate the connection established successfully,
And send L2CAP_COMMAND_REJECT_RSP to reject the unknow command(the extra three bytes of 0) contained in L2CAP_CONNECTION_REQ.
In step 5, the Lower Tester can continue sending L2CAP_CONFIGURATION_REQ because the connection has been established successfully,
So in my opinion, the Configure Request sent by IUT is also a correct behaviour.
>
> > < ACL Data TX: Handle 1 flags 0x00 dlen 10
> > L2CAP: Command Reject (0x01) ident 0 len 2
> > Reason: Command not understood (0x0000)
> > > HCI Event: Number of Completed Packets (0x13) plen 5
> > Num handles: 1
> > Handle: 1 Address: 00:1B:DC:F4:B3:E1 (Vencer Co., Ltd.)
> > Count: 2
> > > HCI Event: Number of Completed Packets (0x13) plen 5
> > Num handles: 1
> > Handle: 1 Address: 00:1B:DC:F4:B3:E1 (Vencer Co., Ltd.)
> > Count: 1
> > > ACL Data RX: Handle 1 flags 0x02 dlen 25
> > L2CAP: Configure Response (0x05) ident 3 len 17
> > Source CID: 64
> > Flags: 0x0000
> > Result: Success (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
> >
> > Signed-off-by: Xigang(Ted) Feng <Xigang.Feng@xxxxxxxxxxxxx>
> > ---
> > net/bluetooth/l2cap_core.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > index 17ca13e8c044..c3af7727ee1e 100644
> > --- a/net/bluetooth/l2cap_core.c
> > +++ b/net/bluetooth/l2cap_core.c
> > @@ -6534,6 +6534,14 @@ static inline void l2cap_sig_channel(struct
> l2cap_conn *conn,
> > skb_pull(skb, len);
> > }
> >
> > + if (skb->len) {
> > + struct l2cap_cmd_rej_unk rej;
> > +
> > + rej.reason = cpu_to_le16(L2CAP_REJ_NOT_UNDERSTOOD);
> > + l2cap_send_cmd(conn, 0, L2CAP_COMMAND_REJ,
> > + sizeof(rej), &rej);
> > + }
> > +
> > drop:
> > kfree_skb(skb);
> > }
> > --
> > 2.34.1
> --
> Luiz Augusto von Dentz
Best Regards,
Xigang
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