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From: Szymon Janc <szymon.janc@gmail.com>
To: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Cc: linux-bluetooth@vger.kernel.org
Subject: Re: [RFC 1/2] doc: Add reauthentication commands and event to Management API
Date: Mon, 27 May 2013 20:50:52 +0200
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In-Reply-To: <20130514231538.GA395@samus.indt.org>
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On Tuesday 14 May 2013 20:15:38 Vinicius Costa Gomes wrote:
> Hi Szymon,

Hi Vinicius,

> 
> On 23:23 Tue 14 May, Szymon Janc wrote:
> > Those will be used to allow/disallow of performing remote device
> > reauthentication.
> 
> I guess you could expand this explaining why you need this in the MGMT API,
> i.e. why this can't be implemented on userspace only.

This will allow to avoid ACL disconnect in case of auth failure and should
allow to reauth also for incoming connections e.g. this is what Android do.
I couldn't figure out how this could be achieved in userspace only but if it
is possible I'm totally after userspace-only implementation.

> > ---
> > 
> >  doc/mgmt-api.txt |  105
> >  ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed,
> >  105 insertions(+)
> > 
> > diff --git a/doc/mgmt-api.txt b/doc/mgmt-api.txt
> > index 1e450e4..96603cd 100644
> > --- a/doc/mgmt-api.txt
> > +++ b/doc/mgmt-api.txt
> > @@ -1223,6 +1223,82 @@ Set Device ID Command
> > 
> >  	Possible errors:	Invalid Parameters
> >  	
> >  				Invalid Index
> > 
> > +Set Reauthentication Policy Command
> > +===================================
> > +
> > +	Command Code:		0x0029
> > +	Controller Index:	<non-controller>
> > +	Command Parameters:	Policy (1 Octet)
> > +	Return Parameters:
> > +
> > +	This command is used to change kernel policy regarding remote device
> > +	reauthentication. When remote device reports no link key presence 
while
> > +	kernel holds link key for this device action taken by kernel depends 
on
> > +	selected policy.
> > +
> > +	The Policy parameter selects desired policy:
> > +
> > +		0x00	Disallow
> > +		0x01	Ask for consent
> > +		0x02	Reauthenticate without asking for consent
> > +
> > +	By default 'Disconnect' policy is used. Selecting 'Ask for consent'
> 
> Minor nitpick, here "Disconnect" should read "Disallow".

Will fix in next version.

> 
> > +	policy will result in emmiting 'Reauthentication Consent Event' if
> > +	circumstance described above occurs.
> > +
> > +	This command generates a Command Complete event on success or
> > +	a Command Status event on failure.
> > +
> > +	Possible errors:	Invalid Parameters
> > +
> > +Reauthentication Consent Reply Command
> > +======================================
> > +
> > +	Command Code:		0x002A
> > +	Controller Index:	<controller id>
> > +	Command Parameters:	Address (6 Octets)
> > +				Address_Type (1 Octet)
> > +	Return Parameters:	Address (6 Octets)
> > +				Address_Type (1 Octet)
> > +
> > +	This command is used to respond to a Reauthentication Consent event.
> > +	This will result in current link key being removed by kernel and new
> > +	authentication process will start.
> > +
> > +	This command can only be used when the controller is powered.
> > +
> > +	This command generates a Command Complete event on success
> > +	or failure.
> > +
> > +	Possible errors:	Not Connected
> > +				Invalid Parameters
> > +				Not Powered
> > +				Invalid Index
> > +				Failed
> > +
> > +Reauthentication Consent Negative Reply Command
> > +===============================================
> > +
> > +	Command Code:		0x002B
> > +	Controller Index:	<controller id>
> > +	Command Parameters:	Address (6 Octets)
> > +				Address_Type (1 Octet)
> > +	Return Parameters:	Address (6 Octets)
> > +				Address_Type (1 Octet)
> > +
> > +	This command is used to return a negative response to a 
Reauthentication
> > +	Consent event.
> > +
> > +	This command can only be used when the controller is powered.
> > +
> > +	This command generates a Command Complete event on success
> > +	or failure.
> > +
> > +	Possible errors:	Not Connected
> > +				Invalid Parameters
> > +				Not Powered
> > +				Invalid Index
> > +				Failed
> > 
> >  Command Complete Event
> >  ======================
> > 
> > @@ -1621,3 +1697,32 @@ Event Parameters	Address (6 Octets)
> > 
> >  	The Passkey parameter indicates the passkey to be shown to the
> >  	user whereas the Entered parameter indicates how many characters
> >  	the user has entered on the remote side.
> > 
> > +
> > +Reauthentication Consent Event
> > +==============================
> > +
> > +Event Code		0x0018
> > +Controller Index	<controller id>
> > +Event Parameters	Address (6 Octets)
> > +			Address_Type (1 Octet)
> > +
> > +	This event is used to request a consent for reauthentication. It is
> > +	emmited when remote device reports no link key presence while kernel
> > +	holds link key and reuthentication policy for this device is set to
> > +	'Ask for consent'.
> > +
> > +	User space should respond to this command either using the
> > +	Reauthentication Consent Reply or the Reauthentication Consent 
Negative
> > +	Reply command.
> > +
> > +Reauthentication Policy Changed Event
> > +=====================================
> > +
> > +Event Code		0x0019
> > +Controller Index	<non-controller>
> > +Event Parameters	Policy (1 Octet)
> > +
> > +	This event indicates that reauthentication policy has been changed
> > +	using Set Reauthentication Policy command. The event will only be sent
> > +	to Management sockets other than the one through which the command was
> > +	sent.
> 
> I still can't see the reason for this. Is it because this policy is global
> (not per-controller)?

This is pretty much the same as for device blocked/unblocked/unpaired events.
There is no point in informing user that set policy about policy change.

-- 
Szymon K. Janc
szymon.janc@gmail.com