When doing SMP over BR/EDR some of the routines can be shared with the
LE functionality whereas others needs to be split into their own BR/EDR
specific branches. This patch implements the split of BR/EDR specific
SMP code from the LE-only code, making sure SMP over BR/EDR works as
specified.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch adds the very basic code for creating and destroying SMP
L2CAP channels for BR/EDR connections.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

To make it possible to use LE SC functionality over BR/EDR with pre-4.1
controllers (that do not support BR/EDR SC links) it's useful to be able
to force LE SC operations even over a traditional SSP protected link.
This patch adds a debugfs switch to force a special debug flag which is
used to skip the checks for BR/EDR SC support.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

For LE Secure Connections we want to trigger cross transport key
generation only if a new link key was actually created during the BR/EDR
connection. This patch adds a new flag to track this information.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

The HCI_USE_DEBUG_KEYS flag is intended to force our side to always use
debug keys for pairing. This means both BR/EDR SSP as well as SMP with
LE Secure Connections. This patch updates the SMP code to use the debug
keys instead of generating a random local key pair when the flag is set.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Since we don not actively try to clear the keypress notification bit we
might get these PDUs. To avoid failing the pairing process add a simple
dummy handler for these for now.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

According to the LE SC specification the initiating device sends its
DHKey check first and the non-initiating devices sends its DHKey check
as a response to this. It's also important that the non-initiating
device doesn't send the response if it's still waiting for user input.
In order to synchronize all this a new flag is added.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

The passkey entry mechanism involves either both sides requesting the
user for a passkey, or one side requesting the passkey while the other
one displays it. The behavior as far as SMP PDUs are concerned are
considerably different from numeric comparison and therefore requires
several new functions to handle it.

In essence passkey entry involves both sides gradually committing to
each bit of the passkey which involves 20 rounds of pairing confirm and
pairing random PDUS being sent in both directions.

This patch adds a new smp->passkey_round variable to track the current
round of the passkey commitment and reuses the variables already present
in struct hci_conn for the passkey and entered key count.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

We need to set the correct Link Key type based on the properties of the
LE SC pairing that it was derived from. If debug keys were used the type
should be a debug key, and the authenticated vs unauthenticated
information should be set on what kind of security level was reached.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

If the just-works method was chosen we shouldn't send anything to user
space but simply proceed with sending the DHKey Check PDU. This patch
adds the necessary code for it.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

After generating the LTK we should set the correct type (normal SC or
debug) and authentication information for it.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

It is very unlikely, but to have a 100% guarantee of the generated key
type we need to reject any keys which happen to match the debug key.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

We need to be able to detect if the remote side used a debug key for the
pairing. This patch adds the debug key defines and sets a flag to
indicate that a debug key was used. The debug private key (debug_sk) is
also added in this patch but will only be used in a subsequent patch
when local debug key support is implemented.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch adds code to select the authentication method for Secure
Connections based on the local and remote capabilities. A new
DSP_PASSKEY method is also added for displaying the passkey - something
that is not part of legacy SMP pairing.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

For Secure Connections we'll select the authentication method as soon as
we receive the public key, but only use it later (both when actually
triggering the method as well as when determining the quality of the
resulting LTK). Store the method therefore in the SMP context.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

As the last step of the LE SC pairing process it's time to generate and
distribute keys. The generation part is unique to LE SC and so this
patch adds a dedicated function for it. We also clear the distribution
bits for keys which are not distributed with LE SC, so that the code
shared with legacy SMP will not go ahead and try to distribute them.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Once we receive the DHKey check PDU it's time to first verify that the
value is correct and then proceed with encrypting the link.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

With LE SC, once the user has responded to the numeric comparison it's
time to send DHKey check values in both directions. The DHKey check
value is generated using new smp_f5 and smp_f6 cryptographic functions.
The smp_f5 function is responsible for generating the LTK and the MacKey
values whereas the smp_f6 function takes the MacKey as input and
generates the DHKey Check value.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

After the Pairing Confirm and Random PDUs have been exchanged in LE SC
it's time to generate a numeric comparison value using a new smp_g2
cryptographic function (which also builds on AES-CMAC). This patch adds
the smp_g2 implementation and updates the Pairing Random PDU handler to
proceed with the value genration and user confirmation.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

When LE SC is being used we should always respond to it by sending our
local random number. This patch adds a convenience function for it which
also contains a check for the pre-requisite public key exchange
completion
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Once the public key exchange is complete the next step is for the
non-initiating device to send a SMP Pairing Confirm PDU to the
initiating device. This requires the use of a new smp_f4 confirm value
generation function which in turn builds on the AES-CMAC cryptographic
function.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch adds a handler function for the LE SC SMP Public Key PDU.
When we receive the key we proceed with generating the shared DHKey
value from the remote public key and local private key.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

When the initial pairing request & response PDUs have been exchanged and
both have had the LE SC bit set the next step is to generate a ECDH
key pair and to send the public key to the remote side. This patch adds
basic support for generating the key pair and sending the public key
using the new Public Key SMP PDU. It is the initiating device that sends
the public key first and the non-initiating device responds by sending
its public key respectively (in a subsequent patch).
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch adds a simple ECC library that will act as a fundamental
building block for LE Secure Connections. The library has a simple API
consisting of two functions: one for generating a public/private key
pair and another one for generating a Diffie-Hellman key from a local
private key and a remote public key.

The code has been taken from https://github.com/kmackay/easy-ecc and
modified to conform with the kernel coding style.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Most of the LE Secure Connections SMP crypto functions build on top of
the AES-CMAC function. This patch adds access to AES-CMAC in the kernel
crypto subsystem by allocating a crypto_hash handle for it in a similar
way that we have one for AES-CBC.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Depending on whether Secure Connections is enabled or not we may need to add
the link key generation bit to the key distribution. This patch does the
necessary modifications to the build_pairing_cmd() function.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Now that hci_find_ltk_by_addr is the only LTK lookup function there's no
need to keep the long name anymore. This patch shortens the function
name to simply hci_find_ltk.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Now that LTKs are always looked up based on bdaddr (with EDiv/Rand
checks done after a successful lookup) the hci_find_ltk function is not
needed anymore. This patch removes the function.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

LTKs derived from Secure Connections based pairing are symmetric, i.e.
they should match both master and slave role. This patch updates the LTK
lookup functions to ignore the desired role when dealing with SC LTKs.

Furthermore, with Secure Connections the EDiv and Rand values are not
used and should always be set to zero. This patch updates the LTK lookup
to first use the bdaddr as key and then do the necessary verifications
of EDiv and Rand based on whether the found LTK is for SC or not.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Since LE Secure Connections is a purely host-side feature we should
offer the Secure Connections mgmt setting for any adapter with LE
support. This patch updates the supported settings value and the
set_secure_conn command handler accordingly.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Since the HCI_SC_ENABLED flag will also be used for controllers without
BR/EDR Secure Connections support whenever we need to check specifically
for SC for BR/EDR we also need to check that the controller actually
supports it. This patch adds a convenience macro for check all the
necessary conditions and converts the places in the code that need it to
use it.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

When the looked-up LTK is one generated by Secure Connections pairing
the security level it gives is BT_SECURITY_FIPS. This patch updates the
LTK request event handler to correctly set this level.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

We need a dedicated LTK type for LTK resulting from a Secure Connections
based SMP pairing. This patch adds a new define for it and ensures that
both the New LTK event as well as the Load LTKs command supports it.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch updates the functions which map the SMP authentication
request to a security level and vice-versa to take into account the
Secure Connections feature.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch adds a new SMP flag for tracking whether Secure Connections
is in use and sets the flag when both remote and local side have elected
to use Secure Connections.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

If we haven't enabled SC support on our side we should use the same mask
for the authentication requirement as we were using before SC support
was added, otherwise we should use the extended mask for SC.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

This patch adds basic SMP defines for commands, error codes and PDU
definitions for the LE Secure Connections feature.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

When we get a Link Key Notification HCI event we should already have a
hci_conn object. This should have been created either in the Connection
Request event handler, the hci_connect_acl() function or the
hci_cs_create_conn() function (if the request was not sent by the
kernel).

Since the only case that we'd end up not having a hci_conn in the Link
Key Notification event handler would be essentially broken hardware it's
safe to simply bail out from the function if this happens.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

To pave the way for future fixed channels to be added easily we should
track both the local and remote mask on a per-L2CAP connection (struct
l2cap_conn) basis. So far the code has used a global variable in a racy
way which anyway needs fixing.

This patch renames the existing conn->fixed_chan_mask that tracked
the remote mask to conn->remote_fixed_chan and adds a new variable
conn->local_fixed_chan to track the local mask. Since the HS support
info is now available in the local mask we can remove the
conn->hs_enabled variable.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

The Bluetooth spec states that automatically flushable packets may not
be sent over a LE-U link.
Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>