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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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Fix spelling errors in comments.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
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This reverts commits c6992e9ef2a17e9738b7bb8a03a7fe581a8f9977 and
4cd3362da899a59955146851dd860198b0aaaa75.
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>
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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>
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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>
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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>
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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
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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