Re: 5.41 - Authentication Failed with kernel 4.2.0

Hi Johannes,

On Wed, Aug 10, 2016, Kropf Johannes wrote:

Here is the whole log:

Thanks. I'll filter it so only the relevant stuff (SMP) is present:

quoted

ACL Data RX: Handle 70 flags 0x02 dlen 6                     [hci0] 28.145172

      SMP: Security Request (0x0b) len 1
        Authentication requirement: Bonding, No MITM, Legacy, No Keypresses (0x01)
< ACL Data TX: Handle 70 flags 0x00 dlen 11                    [hci0] 28.209526
      SMP: Pairing Request (0x01) len 6
        IO capability: NoInputNoOutput (0x03)
        OOB data: Authentication data not present (0x00)
        Authentication requirement: Bonding, No MITM, SC, No Keypresses (0x09)
        Max encryption key size: 16
        Initiator key distribution: EncKey Sign LinkKey (0x0d)
        Responder key distribution: EncKey IdKey Sign LinkKey (0x0f)

quoted

ACL Data RX: Handle 70 flags 0x02 dlen 11                    [hci0] 28.348460

      SMP: Pairing Response (0x02) len 6
        IO capability: NoInputNoOutput (0x03)
        OOB data: Authentication data not present (0x00)
        Authentication requirement: Bonding, No MITM, Legacy, No Keypresses (0x01)
        Max encryption key size: 16
        Initiator key distribution: EncKey Sign (0x05)
        Responder key distribution: EncKey IdKey Sign (0x07)
< ACL Data TX: Handle 70 flags 0x00 dlen 21                    [hci0] 28.348510
      SMP: Pairing Confirm (0x03) len 16
        Confim value: 12bd199ba4739a017395109cfa4621b3

quoted

ACL Data RX: Handle 70 flags 0x02 dlen 21                    [hci0] 28.488508

      SMP: Pairing Confirm (0x03) len 16
        Confim value: 41f5f7a6212356d0eefa268f7994844a
< ACL Data TX: Handle 70 flags 0x00 dlen 21                    [hci0] 28.488545
      SMP: Pairing Random (0x04) len 16
        Random value: 4e8d532caf34ab845ff243acf6a0a681

quoted

ACL Data RX: Handle 70 flags 0x02 dlen 6                     [hci0] 28.628456

      SMP: Pairing Failed (0x05) len 1
        Reason: Confirm value failed (0x04)
< HCI Command: Disconnect (0x01|0x0006) plen 3                 [hci0] 28.628506
        Handle: 70
        Reason: Authentication Failure (0x05)
@ Authentication Failed: 5C:31:3E:5E:54:5E (1) status 0x05

That "Confirm value failed" response still looks like something strange
is happening on the remote side - maybe a bug there. Unfortunately I
don't really have any other ideas except going for raw bisecting here if
you have a kernel version this did work with.

The inputs to the function that generates the confirm value are the
local and remote public keys and the random number that was sent over
the air, so there's not much that can go wrong there - also nothing I
can remember that would have changed on the Linux side regarding this
for a long time. This of course assumes that the remote device is using
this error code correctly and doesn't send it for some other condition.

Johan