[PATCH] Bluetooth: Enable LTK distribution to slave devices

[PATCH] Bluetooth: Enable LTK distribution to slave devices

[johan.hedberg]

From: Johan Hedberg <johan.hedberg@intel.com>

So far we've only been requesting the LTK to be distributed to the
master (initiator) of pairing, which is usually enough since it's the
master that will establish future connections and initiate encryption.
However, in the case that both devices support switching to the opposing
role (which seems to be increasingly common) pairing will have to
performed again since the "new" master will not have all information.

As there is no real harm in it, this patch updates the code to always
try distributing the LTK also to the slave device, thereby enabling role
switches for future connections.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
---
 net/bluetooth/smp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 45007362683b..9b1167007653 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -216,7 +216,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
 		req->io_capability = conn->hcon->io_capability;
 		req->oob_flag = SMP_OOB_NOT_PRESENT;
 		req->max_key_size = SMP_MAX_ENC_KEY_SIZE;
-		req->init_key_dist = 0;
+		req->init_key_dist = dist_keys;
 		req->resp_key_dist = dist_keys;
 		req->auth_req = (authreq & AUTH_REQ_MASK);
 		return;
@@ -225,7 +225,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
 	rsp->io_capability = conn->hcon->io_capability;
 	rsp->oob_flag = SMP_OOB_NOT_PRESENT;
 	rsp->max_key_size = SMP_MAX_ENC_KEY_SIZE;
-	rsp->init_key_dist = 0;
+	rsp->init_key_dist = req->init_key_dist & dist_keys;
 	rsp->resp_key_dist = req->resp_key_dist & dist_keys;
 	rsp->auth_req = (authreq & AUTH_REQ_MASK);
 }
-- 
1.8.5.3

Re: [PATCH] Bluetooth: Enable LTK distribution to slave devices

[Vinicius Costa Gomes]

Hi Johan,

On 13:55 Wed 29 Jan, johan.hedberg@gmail.com wrote:
> From: Johan Hedberg <johan.hedberg@intel.com>
>
> So far we've only been requesting the LTK to be distributed to the
> master (initiator) of pairing, which is usually enough since it's the
> master that will establish future connections and initiate encryption.
> However, in the case that both devices support switching to the opposing
> role (which seems to be increasingly common) pairing will have to
> performed again since the "new" master will not have all information.
>
> As there is no real harm in it, this patch updates the code to always
> try distributing the LTK also to the slave device, thereby enabling role
> switches for future connections.
>
> Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
> ---

Looks good. Ack.


Cheers,
--
Vinicius

Re: [PATCH] Bluetooth: Enable LTK distribution to slave devices

[Marcel Holtmann]

Hi Johan,

> So far we've only been requesting the LTK to be distributed to the
> master (initiator) of pairing, which is usually enough since it's the
> master that will establish future connections and initiate encryption.
> However, in the case that both devices support switching to the opposing
> role (which seems to be increasingly common) pairing will have to
> performed again since the "new" master will not have all information.
> 
> As there is no real harm in it, this patch updates the code to always
> try distributing the LTK also to the slave device, thereby enabling role
> switches for future connections.
> 
> Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
> ---
> net/bluetooth/smp.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel