When we receive FST Setup Request when session already exists, the
following validations take place:
1. we drop the frame if needed according to MAC comparison
2. we drop the frame if the session is "not pending", i.e., if FST
Setup Response was already exchanged (sent or received).
There are two issues with the above:
1. MAC comparison is relevant only before the Setup Response exchange.
In other words, Setup Request should not be dropped due to MAC
comparison after Setup Response has been exchanged.
2. Receiving Setup Request after Setup Response exchange most likely
means that FST state machine is out of sync with the peer. Dropping
the Setup Request will not help solve this situation.
The fix is:
1. do MAC comparison only if session is "pending", i.e., Setup Response
was not yet exchanged.
2. In case Setup Response was already exchanged, reset our session and
handle the Setup Request as if it arrived when session doesn't exist.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Modify the FST peer connection check so it won't skip peers without MB
IEs making it more permissive for peers that didn't provide MB IEs
during association request. This can be helpful, e.g., in cases where a
STA's interface connected before it was added to the FST group. This
allows the AP to receive FST Action frames and initiate session with a
STA via STA's interface that doesn't expose MB IEs.
The adjusted FST protocol is still safe, as it protects itself in many
other ways (checking band info and it's accordance to the interfaces,
Setup IDs, connection states of the interfaces involved, etc.)
effectively avoiding all types of invalid situations.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
FST STA should always expose its MB IEs regardless of its connection
state and whether the connected AP is currently FST-enabled or not.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This buffer is owned by the FST module, so mark it const in the
set_ies() callback to make it clearer which component is responsible for
modifying and freeing this.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This fixes an issue where freed MB IEs buffer memory could potentially
have been accessed after an interface is detached from FST group.
Without this fix, if an interface is detached from FST group, it can use
MB IEs buffer previously set by fst_iface_set_ies(), although the buffer
was released by fst_iface_delete().
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
The foreach_fst_group() loop needs "break-if-found", not
"continue-if-not-found" to do the search iteration properly. If there
were multiple groups, the previous design could have failed to find the
interface.
Signed-off-by: Jouni Malinen <j@w1.fi>
fst_read_next_text_param() is never called with buflen <= 1, so this
separate error path is practically unreachable. Merge it with another
error path to make this a bit more compact.
Signed-off-by: Jouni Malinen <j@w1.fi>
It is possible for there to be multiple FST groups, so the hardcoded
mechanism of selecting the first one when sending out an event message
may not be sufficient. Get the interface from the caller, if available,
and if not, go through all groups in search of an interface to send the
event on.
Signed-off-by: Jouni Malinen <j@w1.fi>
It is possible for there to be multiple FST groups, so the hardcoded
mechanism of selecting the first one when sending out an event message
may not be sufficient. Get the interface from the caller, if available,
and if not, go through all groups in search of an interface to send the
event on.
Signed-off-by: Jouni Malinen <j@w1.fi>
Now that both hostapd and wpa_supplicant already enforce no duplicate
fst_attach() calls, there is no need for this check within fst_attach().
Signed-off-by: Jouni Malinen <j@w1.fi>
Dialog token is only 8 bits and maintaining u32 version of it in struct
fst_group resulted in incorrect wrap-around behavior in
fst_group_assign_dialog_token(). It was possible to assign u8
dialog_token value 0 because of this. Fix this by using u8 variable
consistently.
Signed-off-by: Jouni Malinen <j@w1.fi>
While this is always supposed to be the first element, check that this
is indeed the case instead of blindly using values from within the
element.
Signed-off-by: Jouni Malinen <j@w1.fi>
The Element ID and Length subfields are not supposed to be included in
the Length. In addition, both of these subfields needs to be filled in
even for non-zero status code cases.
Signed-off-by: Jouni Malinen <j@w1.fi>
The space separator between the command and the parameter was not
skipped properly and the first integer ended up being interpreted as 0
in all cases.
Signed-off-by: Jouni Malinen <j@w1.fi>
fst_session_is_in_progress() is already checked as part of
fst_find_session_in_progress() before calling
fst_session_handle_action(). This is the only call path that can reach
fst_session_handle_tear_down() and as such, fst_session_is_in_progress()
cannot return 0 here.
Signed-off-by: Jouni Malinen <j@w1.fi>
There was a mix of EINVAL and -EINVAL returns through the FST
implementation. Make this more consistent by always returning -EINVAL in
error cases.
Signed-off-by: Jouni Malinen <j@w1.fi>
The caller is not expected to free or modify the value since this is
returning a reference to a buffer maintained by the upper layer.
Signed-off-by: Jouni Malinen <j@w1.fi>
There is no need to add new functions with more or less identical
functionality of an already available helper function.
Signed-off-by: Jouni Malinen <j@w1.fi>
Typecasting &mgmt->u.action.u.fst_action to a struct pointer for various
FST Action frame payloads seemed to be triggering static analyzer
warnings about bounds checking since sizeof(mgmt->u.action.u.fst_action)
== 1 even though that is really a variable length structure. Try to
avoid this by calculating the pointer for the beginning of the frame
instead of variable length struct. (CID 125642)
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
These are confusing when the style used with the couple of FST IE checks
differs from the rest of hostapd/wpa_supplicant implementation.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
There is no need for this function to be an inline function in a header
file since it is used only within fst_group.c.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Commit 717333f4e4 ('FST: Add the Fast
Session Transfer (FST) module') performed incorrect frame length
validation for Setup Request (did not remove 24+1 header from
consideration) and did not include payload validation for other FST
Action frames. Fix these by explicitly verifying that the payload of
these frames is sufficiently long before reading the values from there.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Fast Session Transfer (FST) is the transfer of a session from a channel
to another channel in a different frequency band. The term "session"
refers to non-physical layer state information kept by a pair of
stations (STAs) that communicate directly (i.e., excludes forwarding).
The FST is implemented in accordance with IEEE Std 802.11ad-2012.
Definitions
* FST interface - an interface for which FST functionality is enabled
* FST group - a bunch of FST interfaces representing single
multi-band STA
* FST peer - a multi-band capable STA connected
* FST module - multi-band operation functionality implemented in
accordance with IEEE Std 802.11ad-2012 (see 10.32
Multi-band operation) as a part of hostapd/wpa_supplicant
* FST manager - an external application that implements custom FST
related logic, using the FST module's interfaces
accessible via CLI or D-Bus
This commit introduces only the FST module. Integration of the FST
module into the hostapd/wpa_supplicant and corresponding CLI/D-Bus
interfaces and FST related tests are covered in separate commits.
FST manager application is out of scope of these commits.
As FST aggregates a few interfaces into FST group, the FST module uses
global CLI for both commands and notifications. It also exposes
alternative non-interface based D-Bus subtree for this purposes.
Configuration and Initialization
* FST functionality can enabled by compilation flag (CONFIG_FST)
* hostapd/wpa_supplicant controlling multiple interfaces are used for
FST
* once enabled by compilation, the FST can be enabled for specific
interfaces in the configuration files
* FST interfaces are aggregated in FST groups (fst_group_id config file
entry), where each FST group:
- represents one multi-band device
- should have two or more FST interfaces in it
* priority (fst_priority config file entry) must be configured for each
FST interface. FST interface with higher priority is the interface FST
will always try to switch to. Thus, for example, for the maximal
throughput, it should be the fastest FST interface in the FST setup.
* default Link Loss Timeout (LLT) value can be configured for each FST
interface (fst_llt config file entry). It represents LLT to be used
by FST when this interface is active.
* FST interfaces advertise the Multi-band capability by including the
Multi-band element in the corresponding frames
FST CLI commands:
* fst list_groups - list FST groups configured.
* fst list_ifaces - list FST interfaces which belong to specific group
* fst iface_peers - list Multi-Band STAs connected to specific interface
* fst list_sessions - list existing FST sessions
* fst session_get - get FST session info
* fst session_add - create FST session object
* fst session_set - set FST session parameters (old_iface, new_iface,
peer_addr, llt)
* fst session_initiate - initiate FST setup
* fst session_respond - respond to FST setup establishemnt attempt by
counterpart
* fst session_transfer - initiate FST switch
* fst session_teardown - tear down FST Setup but leave the session object
for reuse
* fst session_remove - remove FST session object
FST CLI notifications:
* FST-EVENT-PEER - peer state changed (CONNECT/DISCONNECT)
* FST-EVENT-SESSION - FST session level notification with following
sub-events:
- EVENT_FST_SESSION_STATE - FST session state changed
- EVENT_FST_ESTABLISHED - previously initiated FST session became
established
- EVENT_FST_SETUP - new FST session object created due to FST session
negotiation attempt by counterpart
All the FST CLI commands and notifications are also implemented on D-Bus
for wpa_supplicant.
IEEE 802.11 standard compliance
FST module implements FST setup statemachine in compliance with IEEE
802.11ad (P802.11-REVmc/D3.3), as it described in 10.32 Multi-band
operation (see also Figure 10-34 - States of the FST setup protocol).
Thus, for example, the FST module initiates FST switch automatically
when FST setup becomes established with LLT=0 in accordance with
10.32.2.2 Transitioning between states.
At the moment, FST module only supports non-transparent STA-based FST
(see 10.32.1 General).
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
