Re: [PATCH 1/2] Bluetooth: Fix legacy pairing with some devices

Hi Szymon,

* Johan Hedberg [off-list ref] [2012-06-29 13:56:53 +0300]:

Hi Szymon & Gustavo,

On Wed, May 30, 2012, Szymon Janc wrote:

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Some devices e.g. SonyEricsson Xperia ray and arc S don't do SDP search
before pairing. No L2CAP is connected so default HCI_DISCONN_TIMEOUT
(2 seconds) timeout value is being used. This results in problems with
legacy pairing as remote user has only few seconds to enter PIN before
ACL is disconnected.

Increase disconnect timeout to HCI_PAIRING_TIMEOUT if SSP is disabled
and no linkey exists.

does this only happen with SSP disabled?

Yes, I've seen this only with SSP disabled.
After name request remote devices ask user to enter PIN and before user is
able to do so (4 sec only) link is disconnected (cause we didn't get pin
request event yet).

For SSP hci_conn_hold is called in hci_io_capa_request_evt so link is not
disconnected.

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Also add the hcidump output to the commit message would be helpful.

hcidump for ssp disabled [1] and ssp enabled [2] below.

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Signed-off-by: Szymon Janc <redacted>
---
 net/bluetooth/hci_event.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ac86b65..98e8020 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c

@@ -1762,7 +1762,12 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		if (conn->type == ACL_LINK) {
 			conn->state = BT_CONFIG;
 			hci_conn_hold(conn);
-			conn->disc_timeout = HCI_DISCONN_TIMEOUT;
+
+			if (!hci_conn_ssp_enabled(conn) &&
+			    !hci_find_link_key(hdev, &ev->bdaddr))

I could add also checking if connection is incoming to narrow case a bit further...

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+				conn->disc_timeout = HCI_PAIRING_TIMEOUT;
+			else
+				conn->disc_timeout = HCI_DISCONN_TIMEOUT;

You are also changing the timeout for a SDP search, for example, to
HCI_PAIRING_TIMEOUT and this is not good. I think we need to be smarter here,
we can't change the behaviour of things like SDP search here.

Maybe we could set timeout back to HCI_DICONN_TIMEOUT when l2cap is
connected (or disconnected)?  That should cover SDP search case..

What happened to getting this patch upstream? To me it looks like a
definitely needed fix. After adding the fix to restore a sensible value
for disc_timeout after an L2CAP connect request either way and adding a
better explanation to the commit message (that we only get the PIN
request after user has entered one on the remote side, including a
hcidump of this) I think this should go upstream. If this had been
processed in a timely manner it could have made it to 3.5 but now it
seems too late for that (as it's not strictly speaking a regression from
3.4).

Could you re-do this patch as Johan says so we can try push it to 3.5?

	Gustavo