[v1] adapter: Manage device state of cross-transport SMP keys

Cross-transport derived ltk/csrk/irk are reported to bluetoothd from
kernel with BR/EDR address type, and bluetoothd doesn't treat it as LE
paired/bonded. In this case, bluetoothd won't send remove bond operation
with LE address type to kernel when executing unpair, so SMP keys are
retained in kernel list. Then RPA is getting resolved since we still
have irk which was not deleted when unpair device is done because only
link key is deleted since addr type is bredr.

What’s more, pair LE of the same address will always fail in kernel
for ltk existence, and send back AlreadyExists error, but device state
is still unpaired/unbonded in bluetoothd.

So bluetoothd needs to consider LE paired/bonded when receiving SMP keys
even if they are cross-transport derived.
---
 src/adapter.c | 53 ++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 13 deletions(-)

Hi Luiz, Please check the comment inline, Please correct me if I'm wrong.

On 8/26/2024 9:56 PM, Luiz Augusto von Dentz wrote:
> Hi Cheng,
> 
> On Mon, Aug 26, 2024 at 3:05 AM Cheng Jiang <quic_chejiang@quicinc.com> wrote:
>>
>> Cross-transport derived ltk/csrk/irk are reported to bluetoothd from
>> kernel with BR/EDR address type, and bluetoothd doesn't treat it as LE
>> paired/bonded. In this case, bluetoothd won't send remove bond operation
>> with LE address type to kernel when executing unpair, so SMP keys are
>> retained in kernel list. Then RPA is getting resolved since we still
>> have irk which was not deleted when unpair device is done because only
>> link key is deleted since addr type is bredr.
>>
>> What’s more, pair LE of the same address will always fail in kernel
>> for ltk existence, and send back AlreadyExists error, but device state
>> is still unpaired/unbonded in bluetoothd.
>>
>> So bluetoothd needs to consider LE paired/bonded when receiving SMP keys
>> even if they are cross-transport derived.
>> ---
>>  src/adapter.c | 53 ++++++++++++++++++++++++++++++++++++++-------------
>>  1 file changed, 40 insertions(+), 13 deletions(-)
>>
>> diff --git a/src/adapter.c b/src/adapter.c
>> index 245de4456..4e5af9579 100644
>> --- a/src/adapter.c
>> +++ b/src/adapter.c
>> @@ -8647,6 +8647,7 @@ static void new_link_key_callback(uint16_t index, uint16_t length,
>>         struct btd_adapter *adapter = user_data;
>>         struct btd_device *device;
>>         char dst[18];
>> +       uint8_t addr_type;
>>
>>         if (length < sizeof(*ev)) {
>>                 btd_error(adapter->dev_id, "Too small new link key event");
>> @@ -8666,7 +8667,13 @@ static void new_link_key_callback(uint16_t index, uint16_t length,
>>                 return;
>>         }
>>
>> -       device = btd_adapter_get_device(adapter, &addr->bdaddr, addr->type);
>> +       /*
>> +        * For LE public address, key here is cross-transport derived,
>> +        * so consider it as BR/EDR public address.
>> +        *
>> +        */
>> +       addr_type = addr->type == BDADDR_LE_PUBLIC ? BDADDR_BREDR : addr->type;
>> +       device = btd_adapter_get_device(adapter, &addr->bdaddr, addr_type);
>>         if (!device) {
>>                 btd_error(adapter->dev_id,
>>                                 "Unable to get device object for %s", dst);
>> @@ -8682,7 +8689,7 @@ static void new_link_key_callback(uint16_t index, uint16_t length,
>>                 device_set_bonded(device, BDADDR_BREDR);
>>         }
>>
>> -       bonding_complete(adapter, &addr->bdaddr, addr->type, 0);
>> +       bonding_complete(adapter, &addr->bdaddr, addr_type, 0);
>>  }
>>
>>  static void store_ltk_group(struct btd_adapter *adapter, const bdaddr_t *peer,
>> @@ -8773,6 +8780,7 @@ static void new_long_term_key_callback(uint16_t index, uint16_t length,
>>         struct btd_device *device;
>>         bool persistent;
>>         char dst[18];
>> +       uint8_t addr_type;
>>
>>         if (length < sizeof(*ev)) {
>>                 btd_error(adapter->dev_id, "Too small long term key event");
>> @@ -8784,7 +8792,13 @@ static void new_long_term_key_callback(uint16_t index, uint16_t length,
>>         DBG("hci%u new LTK for %s type %u enc_size %u",
>>                 adapter->dev_id, dst, ev->key.type, ev->key.enc_size);
>>
>> -       device = btd_adapter_get_device(adapter, &addr->bdaddr, addr->type);
>> +       /*
>> +        * For BR/EDR public address, key here is cross-transport derived,
>> +        * so consider it as LE public address for SMP.
>> +        *
>> +        */
> 
> This is only the case if, an only if, the device is a dual-mode
> device, so this probably need to be checked that we don't attempt to
> do this regardless.
Only the dual-mode device supports Cross-transport derived Keys. From BLE keys to BR/EDR keys, vice versa. If
single mode device, the addr->type always is BDADDR_BREDR in link key callback. and BDADDR_LE_PUBLIC or
BDADDR_LE_RANDOM for LTK/CSRK/IRK callback. 

Link Key is for BR/EDR, so we check the address type is BDADDR_LE_PUBLIC or not, if yes, treated as BR/EDR,
it means the link key is derived from BLE bearer. Otherwise, use the original addr type. LTK, CSRK, IRK are
related to BLE, so checked the address type is BDADDR_BREDR or not, if yes, treated as BLE address, it means
the BLE related key are derived from BR/EDR bearer. 

The change seems not affect the current logic, could you please help to explain more what need to check? Thanks!
> 
>> +       addr_type = addr->type == BDADDR_BREDR ? BDADDR_LE_PUBLIC : addr->type;
>> +       device = btd_adapter_get_device(adapter, &addr->bdaddr, addr_type);
>>         if (!device) {
>>                 btd_error(adapter->dev_id,
>>                                 "Unable to get device object for %s", dst);
>> @@ -8802,8 +8816,7 @@ static void new_long_term_key_callback(uint16_t index, uint16_t length,
>>          * be persistently stored.
>>          *
>>          */
>> -       if (addr->type == BDADDR_LE_RANDOM &&
>> -                               (addr->bdaddr.b[5] & 0xc0) != 0xc0)
>> +       if (addr_type == BDADDR_LE_RANDOM && (addr->bdaddr.b[5] & 0xc0) != 0xc0)
>>                 persistent = false;
>>         else
>>                 persistent = !!ev->store_hint;
>> @@ -8817,15 +8830,15 @@ static void new_long_term_key_callback(uint16_t index, uint16_t length,
>>                 rand = le64_to_cpu(key->rand);
>>
>>                 store_longtermkey(adapter, &key->addr.bdaddr,
>> -                                       key->addr.type, key->val, key->central,
>> +                                       addr_type, key->val, key->central,
>>                                         key->type, key->enc_size, ediv, rand);
>>
>> -               device_set_bonded(device, addr->type);
>> +               device_set_bonded(device, addr_type);
>>         }
>>
>>         device_set_ltk(device, ev->key.val, ev->key.central, ev->key.enc_size);
>>
>> -       bonding_complete(adapter, &addr->bdaddr, addr->type, 0);
>> +       bonding_complete(adapter, &addr->bdaddr, addr_type, 0);
>>  }
>>
>>  static void new_csrk_callback(uint16_t index, uint16_t length,
>> @@ -8837,6 +8850,7 @@ static void new_csrk_callback(uint16_t index, uint16_t length,
>>         struct btd_adapter *adapter = user_data;
>>         struct btd_device *device;
>>         char dst[18];
>> +       uint8_t addr_type;
>>
>>         if (length < sizeof(*ev)) {
>>                 btd_error(adapter->dev_id, "Too small CSRK event");
>> @@ -8848,7 +8862,13 @@ static void new_csrk_callback(uint16_t index, uint16_t length,
>>         DBG("hci%u new CSRK for %s type %u", adapter->dev_id, dst,
>>                                                                 ev->key.type);
>>
>> -       device = btd_adapter_get_device(adapter, &addr->bdaddr, addr->type);
>> +       /*
>> +        * For BR/EDR public address, key here is cross-transport derived,
>> +        * so consider it as LE public address for SMP.
>> +        *
>> +        */
>> +       addr_type = addr->type == BDADDR_BREDR ? BDADDR_LE_PUBLIC : addr->type;
> 
> Ditto.
> 
>> +       device = btd_adapter_get_device(adapter, &addr->bdaddr, addr_type);
>>         if (!device) {
>>                 btd_error(adapter->dev_id,
>>                                 "Unable to get device object for %s", dst);
>> @@ -8911,6 +8931,7 @@ static void new_irk_callback(uint16_t index, uint16_t length,
>>         struct btd_device *device, *duplicate;
>>         bool persistent;
>>         char dst[18], rpa[18];
>> +       uint8_t addr_type;
>>
>>         if (length < sizeof(*ev)) {
>>                 btd_error(adapter->dev_id, "Too small New IRK event");
>> @@ -8922,16 +8943,22 @@ static void new_irk_callback(uint16_t index, uint16_t length,
>>
>>         DBG("hci%u new IRK for %s RPA %s", adapter->dev_id, dst, rpa);
>>
>> +       /*
>> +        * For BR/EDR public address, key here is cross-transport derived,
>> +        * so consider it as LE public address for SMP.
>> +        *
>> +        */
>> +       addr_type = addr->type == BDADDR_BREDR ? BDADDR_LE_PUBLIC : addr->type;
> 
> Ditto.
> 
>>         if (bacmp(&ev->rpa, BDADDR_ANY)) {
>>                 device = btd_adapter_get_device(adapter, &ev->rpa,
>>                                                         BDADDR_LE_RANDOM);
>>                 duplicate = btd_adapter_find_device(adapter, &addr->bdaddr,
>> -                                                               addr->type);
>> +                                                               addr_type);
>>                 if (duplicate == device)
>>                         duplicate = NULL;
>>         } else {
>>                 device = btd_adapter_get_device(adapter, &addr->bdaddr,
>> -                                                               addr->type);
>> +                                                               addr_type);
>>                 duplicate = NULL;
>>         }
>>
>> @@ -8941,7 +8968,7 @@ static void new_irk_callback(uint16_t index, uint16_t length,
>>                 return;
>>         }
>>
>> -       device_update_addr(device, &addr->bdaddr, addr->type);
>> +       device_update_addr(device, &addr->bdaddr, addr_type);
>>
>>         if (duplicate)
>>                 device_merge_duplicate(device, duplicate);
>> @@ -8950,7 +8977,7 @@ static void new_irk_callback(uint16_t index, uint16_t length,
>>         if (!persistent)
>>                 return;
>>
>> -       store_irk(adapter, &addr->bdaddr, addr->type, irk->val);
>> +       store_irk(adapter, &addr->bdaddr, addr_type, irk->val);
>>
>>         btd_device_set_temporary(device, false);
>>  }
>> --
>> 2.25.1
>>
>>
> 
>