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>
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>
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>
Now that the SMP related key lists are converted to RCU there is nothing
in smp_cmd_sign_info() or smp_cmd_ident_addr_info() that would require
taking the hdev lock (including the smp_distribute_keys call). This
patch removes this unnecessary locking.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch set converts the hdev->identity_resolving_keys list to use
RCU to eliminate the need to use hci_dev_lock/unlock.
An additional change that must be done is to remove use of
CRYPTO_ALG_ASYNC for the hdev-specific AES crypto context. The reason is
that this context is used for matching RPAs and the loop that does the
matching is under the RCU read lock, i.e. is an atomic section which
cannot sleep.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch set converts the hdev->long_term_keys list to use RCU to
eliminate the need to use hci_dev_lock/unlock.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
So far smp_sufficient_security() has returned false if we're encrypted
with an STK but do have an LTK available. However, for the sake of LE
CoC servers we do want to let the incoming connection through even
though we're only encrypted with the STK.
This patch adds a key preference parameter to smp_sufficient_security()
with two possible values (enum used instead of bool for readability).
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
By default lockdep considers all L2CAP channels equal. This would mean
that we get warnings if a channel is locked when another one's lock is
tried to be acquired in the same thread. This kind of inter-channel
locking dependencies exist in the form of parent-child channels as well
as any channel wishing to elevate the security by requesting procedures
on the SMP channel.
To eliminate the chance for these lockdep warnings we introduce a
nesting level for each channel and use that when acquiring the channel
lock. For now there exists the earlier mentioned three identified
categories: SMP, "normal" channels and parent channels (i.e. those in
BT_LISTEN state). The nesting level is defined as atomic_t since we need
access to it before the lock is actually acquired.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The mgmt_user_passkey_request and related functions do not do anything
else except read access to hdev->id. This member never changes after the
hdev creation so there is no need to acquire a lock to read it.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This reverts commits c6992e9ef2 and
4cd3362da8.
The reason for the revert is that we cannot have more than one module
initialization function and the SMP one breaks the build with modular
kernels. As the proper fix for this is right now looking non-trivial
it's better to simply revert the problematic patches in order to keep
the upstream tree compilable.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch adds self-tests for the c1 and s1 crypto functions used for
SMP pairing. The data used is the sample data from the core
specification.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch adds a basic skeleton for SMP self-tests. The tests are put
behind a new configuration option since running them will slow down the
boot process. For now there are no actual tests defined but those will
come in a subsequent patch.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
In order to make unit testing possible we need to make the SMP crypto
functions only take the crypto context instead of the full SMP context
(the latter would require having hci_dev, hci_conn, l2cap_chan,
l2cap_conn, etc around). The drawback is that we no-longer get the
involved hdev in the debug logs, but this is really the only way to make
simple unit tests for the code.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
We can only determine the final security level when both pairing request
and response have been exchanged. When initiating pairing the starting
target security level is set to MEDIUM unless explicitly specified to be
HIGH, so that we can still perform pairing even if the remote doesn't
have MITM capabilities. However, once we've received the pairing
response we should re-consult the remote and local IO capabilities and
upgrade the target security level if necessary.
Without this patch the resulting Long Term Key will occasionally be
reported to be unauthenticated when it in reality is an authenticated
one.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org
This is a trivial change to use a proper define for the NoInputNoOutput
IO capability instead of hard-coded values.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
There are several places that need to determine the security level that
an LTK can provide. This patch adds a convenience function for this to
help make the code more readable.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
When the local IO capability is NoInputNoOutput any attempt to convert
the remote authentication requirement to a target security level is
futile. This patch makes sure that we set the target security level at
most to MEDIUM if the local IO capability is NoInputNoOutput.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
All the cases where we mark SMP commands as dissalowed are their
respective command handlers. We can therefore simplify the code by
always clearing the bit immediately after testing it. This patch
converts the corresponding test_bit() call to a test_and_clear_bit()
call and also removes the now unused SMP_DISALLOW_CMD macro.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The SMP specification states that we should ignore any unknown bits from
the authentication requirement. We already have a define for masking out
unknown bits but we haven't used it in all places so far. This patch
adds usage of the AUTH_REQ_MASK to all places that need it and ensures
that we don't pass unknown bits onward to other functions.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
We do nothing else with the auth variable in smp_cmd_pairing_rsp()
besides passing it to tk_request() which in turn only cares about
whether one of the sides had the MITM bit set. It is therefore
unnecessary to assign a value to it until just before calling
tk_request(), and this value can simply be the bit-wise or of the local
and remote requirements.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
If the remote side is not distributing its IRK but is distributing the
CSRK the next PDU after master identification is the Signing
Information. This patch fixes a missing SMP_ALLOW_CMD() for this in the
smp_cmd_master_ident() function.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Whether through HCI with BR/EDR or SMP with LE when authentication fails
we should also notify any pending Pair Device mgmt command. This patch
updates the mgmt_auth_failed function to take the actual hci_conn object
and makes sure that any pending pairing command is notified and cleaned
up appropriately.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch fixes the following type of static analyzer warning (and
probably a real bug as well as the NULL check should be there for a
reason):
net/bluetooth/smp.c:1182 smp_conn_security() warn: variable dereferenced before check 'conn' (see line 1174)
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
SMP defines quite clearly when certain PDUs are to be expected/allowed
and when not, but doesn't have any explicit request/response definition.
So far the code has relied on each PDU handler to behave correctly if
receiving PDUs at an unexpected moment, however this requires many
different checks and is prone to errors.
This patch introduces a generic way to keep track of allowed PDUs and
thereby reduces the responsibility & load on individual command
handlers. The tracking is implemented using a simple bit-mask where each
opcode maps to its own bit. If the bit is set the corresponding PDU is
allow and if the bit is not set the PDU is not allowed.
As a simple example, when we send the Pairing Request we'd set the bit
for Pairing Response, and when we receive the Pairing Response we'd
clear the bit for Pairing Response.
Since the disallowed PDU rejection is now done in a single central place
we need to be a bit careful of which action makes most sense to all
cases. Previously some, such as Security Request, have been simply
ignored whereas others have caused an explicit disconnect.
The only PDU rejection action that keeps good interoperability and can
be used for all the applicable use cases is to drop the data. This may
raise some concerns of us now being more lenient for misbehaving (and
potentially malicious) devices, but the policy of simply dropping data
has been a successful one for many years e.g. in L2CAP (where this is
the *only* policy for such cases - we never request disconnection in
l2cap_core.c because of bad data). Furthermore, we cannot prevent
connected devices from creating the SMP context (through a Security or
Pairing Request), and once the context exists looking up the
corresponding bit for the received opcode and deciding to reject it is
essentially an equally lightweight operation as the kind of rejection
that l2cap_core.c already successfully does.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
When we're in the process of receiving keys in phase 3 of SMP we keep
track of which keys are still expected in the smp->remote_key_dist
variable. If we still have some key bits set we need to continue waiting
for more PDUs and not needlessly call smp_distribute_keys(). This patch
fixes two such cases in the smp_cmd_master_ident() and
smp_cmd_ident_addr_info() handler functions.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch adds a define for the allowed bits of the key distribution
mask so we don't have to have magic 0x07 constants throughout the code.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Before the move the l2cap_chan the SMP context (smp_chan) didn't have
any kind of proper locking. The best there existed was the
HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for
potential multiple creators of the SMP context.
Now that SMP has been converted to use the l2cap_chan infrastructure and
since the SMP context is directly mapped to a corresponding l2cap_chan
we get the SMP context locking essentially for free through the
l2cap_chan lock. For all callbacks that l2cap_core.c makes for each
channel implementation (smp.c in the case of SMP) the l2cap_chan lock is
held through l2cap_chan_lock(chan).
Since the calls from l2cap_core.c to smp.c are covered the only missing
piece to have the locking implemented properly is to ensure that the
lock is held for any other call path that may access the SMP context.
This means user responses through mgmt.c, requests to elevate the
security of a connection through hci_conn.c, as well as any deferred
work through workqueues.
This patch adds the necessary locking to all these other code paths that
try to access the SMP context. Since mutual exclusion for the l2cap_chan
access is now covered from all directions the patch also removes
unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock
we can simply check whether chan->smp is set to know if there's an SMP
context).
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Now that the identity address update happens through its own deferred
work there's no need to have smp_distribute_keys anymore behind a second
deferred work. This patch removes this extra construction and makes the
code do direct calls to smp_distribute_keys() again.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The identity address update of all channels for an l2cap_conn needs to
take the lock for each channel, i.e. it's safest to do this by a
separate workqueue callback.
Previously this was partially solved by moving the entire SMP key
distribution behind a workqueue. However, if we want SMP context locking
to be correct and safe we should always use the l2cap_chan lock when
accessing it, meaning even smp_distribute_keys needs to take that lock
which would once again create a dead lock when updating the identity
address.
The simplest way to solve this is to have l2cap_conn manage the deferred
work which is what this patch does. A subsequent patch will remove the
now unnecessary SMP key distribution work struct.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
When smp_resume_cb is called if we're not encrypted (i.e. the callback
wasn't called because the connection became encrypted) we shouldn't take
any action at all. This patch moves also the security_timer cancellation
behind this condition.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The SMP security timer used to be able to modify the SMP context state
but now days it simply calls hci_disconnect(). It is therefore
unnecessary to have extra sanity checks for the SMP context after
canceling the timer.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Returning failure from the SMP data parsing function will cause an
immediate disconnect, making any attempts to send a response PDU futile.
This patch updates the function to always either send a response or
return an error, but never both at the same time:
* In the case that HCI_LE_ENABLED is not set we want to send a Pairing Not
Supported response but it is not required to force a disconnection, so
do not set the error return in this case.
* If we get garbage SMP data we can just fail with the handler function
instead of also trying to send an SMP Failure PDU.
* There's no reason to force a disconnection if we receive an unknown SMP
command. Instead simply send a proper Command Not Supported SMP
response.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Relying on the l2cap_conn_del procedure (triggered through the
l2cap_conn_shutdown API) to get the connection disconnected is not
reliable as it depends on all users releasing (through hci_conn_drop)
and that there's at least one user (so hci_conn_drop is called at least
one time).
A much simpler and more reliable solution is to call hci_disconnect()
directly from the SMP code when we want to disconnect. One side-effect
this has is that it prevents any SMP Failure PDU from being sent before
the disconnection, however neither one of the scenarios where
l2cap_conn_shutdown was used really requires this.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
There are no external users of smp_chan_destroy() so make it private to
smp.c. The patch also moves the function higher up in the c-file in
order to avoid forward declarations.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The smp_distribute_keys() function calls smp_notify_keys() which in turn
calls l2cap_conn_update_id_addr(). The l2cap_conn_update_id_addr()
function will iterate through all L2CAP channels for the respective
connection: lock the channel, update the address information and unlock
the channel.
Since SMP is now using l2cap_chan callbacks each callback is called with
the channel lock held. Therefore, calling l2cap_conn_update_id_addr()
would cause a deadlock calling l2cap_chan_lock() on the SMP channel.
This patch moves calling smp_distribute_keys() through a workqueue so
that it is never called from an L2CAP channel callback.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
All places needing to cancel the security timer also call
smp_chan_destroy() in the same go. To eliminate the need to do these two
calls in multiple places simply move the timer cancellation into
smp_chan_destroy().
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch adds an SMP-internal timeout callback to remove the depenency
on (the soon to be removed) l2cap_conn->security_timer. The behavior is
the same as with l2cap_conn->security_timer except that the new
l2cap_conn_shutdown() public function is used instead of the L2CAP core
internal l2cap_conn_del().
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
In the case that the SMP recv callback returns error the calling code in
l2cap_core.c expects that it still owns the skb and will try to free it.
The SMP code should therefore not try to free the skb if it return an
error. This patch fixes such behavior in the SMP command handler
function.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
To restore pre-l2cap_chan functionality we should be trying to
disconnect the connection when receviving garbage SMP data (i.e. when
the SMP command handler fails). This patch renames the command handler
back to smp_sig_channel() and adds a smp_recv_cb() wrapper function for
calling it. If smp_sig_channel() fails the code calls
l2cap_conn_shutdown().
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
There's no need to export the smp_distribute_keys() function since the
resume callback is called in the same scenario. This patch makes the
smp_notify_keys function private (at the same time moving it higher up
in smp.c to avoid forward declarations) and adds a resume callback for
SMP to call it from there instead.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Now that we have all the necessary pieces in place we can fully convert
SMP to use the L2CAP channel infrastructure. This patch adds the
necessary callbacks and removes the now unneeded conn->smp_chan pointer.
One notable behavioral change in this patch comes from the following
code snippet:
- case L2CAP_CID_SMP:
- if (smp_sig_channel(conn, skb))
- l2cap_conn_del(conn->hcon, EACCES);
This piece of code was essentially forcing a disconnection if garbage
SMP data was received. The l2cap_conn_del() function is private to
l2cap_conn.c so we don't have access to it anymore when using the L2CAP
channel callbacks. Therefore, the behavior of the new code is simply to
return errors in the recv() callback (which is simply the old
smp_sig_channel()), but no disconnection will occur.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Now that we have per-adapter SMP data thanks to the root SMP L2CAP
channel we can take advantage of it and attach the AES crypto context
(only used for SMP) to it. This means that the smp_irk_matches() and
smp_generate_rpa() function can be converted to internally handle the
AES context.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch creates the initial SMP L2CAP channels and a skeleton for
their callbacks. There is one per-adapter channel created upon adapter
registration, and then one channel per-connection created through the
new_connection callback. The channels are registered with the reserved
CID 0x1f for now in order to not conflict with existing SMP
functionality. Once everything is in place the value can be changed to
what it should be, i.e. L2CAP_CID_SMP.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
