OWE Transition is described in the WiFi Alliance OWE Specification
version 1.1. The idea behind it is to support both legacy devices
without any concept of OWE as well as modern ones which support the
OWE protocol.
OWE is a somewhat special type of network. Where it advertises an
RSN element but is still "open". This apparently confuses older
devices so the OWE transition procedure was created.
The idea is simple: have two BSS's, one open, and one as a hidden
OWE network. Each network advertises a vendor IE which points to the
other. A device sees the open network and can connect (legacy) or
parse the IE, scan for the hidden OWE network, and connect to that
instead.
Care was taken to handle connections to hidden networks directly.
The policy is being set that any hidden network with the WFA OWE IE
is not connectable via ConnectHiddenNetwork(). These networks are
special, and can only be connected to via the network object for
the paired open network.
When scan results come in from any source (DBus, quick, autoconnect)
each BSS is checked for the OWE Transition IE. A few paths can be
taken here when the IE is found:
1. The BSS is open. The BSSID in the IE is checked against the
current scan results (excluding hidden networks). If a match is
found we should already have the hidden OWE BSS and nothing
else needs to be done (3).
2. The BSS is open. The BSSID in the IE is not found in the
current scan results, and the open network also has no OWE BSS
in it. This will be processed after scan results.
3. The BSS is not open and contains the OWE IE. This BSS will
automatically get added to the network object and nothing else
needs to be done.
After the scan results each network is checked for any non-paired
open BSS's. If found a scan is started for these BSS's per-network.
Once these scan results come in the network is notified.
From here network.c can detect that this is an OWE transition
network and connect to the OWE BSS rather than the open one.
Specifically OWE networks with multiple open/hidden BSS's are troublesome
to scan for with the current APIs. The scan parameters are limited to a
single SSID and even if that was changed we have the potential of hitting
the max SSID's per scan limit. In all, it puts the burden onto the caller
to sort out the SSIDs/frequencies to scan for.
Rather than requiring station to handle this a new scan API was added,
scan_owe_hidden() which takes a list of open BSS's and will automatically
scan for the SSIDs in the OWE transition IE for each.
It is slightly optimized to first check if all the hidden SSID's are the
same. This is the most likely case (e.g. single pair or single network)
and a single scan command can be used. Otherwise individual scan commands
are queued for each SSID/frequency combo.
handshake_util_ap_ie_matches() is used to make sure that the RSN element
received from the Authenticator during handshake / association response
is the same as the one advertised in Beacon/Probe Response frames. This
utility tries to bitwise compare the element first, and only if that
fails, compares RSN members individually.
For FT, bitwise comparison will always fail since the PMKID has to be
included by the Authenticator in any RSN IEs included in Authenticate
& Association Response frames.
Perform the bitwise comparison as an optimization only during processing
of eapol message 3/4. Also keep the parsed rsn information for future
use and to possibly avoid re-parsing it during later checks.
DBus scan is performed in several subsets. In certain corner-case
circumstances it would be possible for autoconnect to run after each
subset scan. Instead, trigger autoconnect only after the dbus scan
completes.
This also works around a condition where ANQP results could trigger
autoconnect too early.
Several invocations of station_set_scan_results() base the
'add_to_autoconnect' parameter on station_is_autoconnecting(). Simplify
the code by having station_set_scan_results() invoke that itself.
'add_to_autoconnect' now becomes an 'intent' parameter, specifying
whether autoconnect path should be invoked as a result of these scan
results or not when station is in an appropriate state. Rename
'add_to_autoconnect' parameter to make this clearer.
If the frequency of the bss is not in the list of frequencies for the
current scan, then this is a cached bss. It was likely already
processed for ANQP before, so skip it.
IWD has restricted SSIDs to only utf8 so they can be displayed but
with the addition of OWE transition networks this is an unneeded
restriction (for these networks). The SSID of an OWE transition
network is never displayed to the user so limiting to utf8 isn't
required.
Allow non-utf8 SSIDs to be scanned for by including the length in
the scan parameters and not relying on strlen().
This is a parser for the WFA OWE Transition element. For now the
optional band/channel bytes will not be parsed as hostapd does not
yet support these and would also require the 802.11 appendix E-1
to be added to IWD. Because of this OWE Transition networks are
assumed to be on the same channel as their open counterpart.
in6_addr.__in6_u.__u6_addr8 is glibc-specific and named differently in
the headers shipped with musl libc for example. The POSIX compliant and
universal way of accessing it is in6_addr.s6_addr.
This was actually broken if triggered because __network_connect
checks if network->connect_after_owe_hidden is set and returns
already in progress. We want to keep this behavior though for
obvious reasons.
To fix this station_connect_network can be called directly which
bypasses the check. This is essentially how ANQP avoids this
problem as well.
Similar to ANQP a connect call could come in while station is
scanning for OWE hidden networks. This is supported in the same
manor by saving away the dbus message and resuming the connection
after the hidden OWE scan.
With the addition of OWE transition network needs to be notified
of the hidden OWE scan which is quite similar to how it is notified
of ANQP. The ANQP event watch can be made generic and reused to
allow other events besides ANQP.
This is being added to support OWE transition mode. For these
type of networks the OWE BSS may contain a different SSID than
that of the network, but the WFA spec requires this be hidden
from the user. This means we need to set the handshake SSID based
on the BSS rather than the network object.
Refactor netconfig_set_dns to be a bit easier to follow and remove use
of macros. Also bail out early if no DNS addresses are provided instead
of building an empty DNS list since resolve_set_dns() simply returns if
a NULL or empty DNS list is provided.
If set, a rule will start matching 'MatchBytes' some number of bytes
into the frame (MatchBytesOffset). This is useful since header
information, addresses, and sequence numbers may be unpredictable
between test runs.
To avoid unintended matches the Prefix property is left unchanged
and will match starting at the beginning of the frame.
Since IWD tries group 20 first all other OWE tests are actually
triggering group negotiation where this test is not. Since this
code is exercised this test can be removed completely, as well
as the additional radio/network.
Kernel keeps transmitting authentication frames until told to stop or an
authentication frame the kernel considers 'final' is received. Detect
cases where the kernel would keep retransmitting, and if auth_proto
encounters a fatal protocol error, prevent these retransmissions from
occuring by sending a Deauthenticate command to the kernel.
Additionally, treat -EBADMSG/-ENOMSG return from auth_proto specially.
These error codes are meant to convey that a frame should be silently
dropped and retransmissions should continue.
This test simulates the scenario where IWDs commit is not acked which
exposes a hostapd bug that ultimately fails the connection. This behavior
can be seen by reverting the commit which works around this issue:
"sae: don't send commit in confirmed state"
With the above patch applied this test should pass.
Note: The existing timeout test was reused as it was not of much use
anyways. All it did was block auth/assoc frames and expect a failure
which didn't exercise any SAE logic anyways.
This works around a hostapd bug (described more in the TODO comment)
which is exposed because of the kernels overly agressive re-transmit
behavior on missed ACKs. Combined this results in a death if the
initial commit is not acked. This behavior has been identified in
consumer access points and likely won't ever be patched for older
devices. Because of this IWD must work around the problem which can
be eliminated by not sending out this commit message.
This bug was reported to the hostapd ML:
https://lists.infradead.org/pipermail/hostap/2021-September/039842.html
This change should not cause any compatibility problems to non-hostapd
access points and is identical to how wpa_supplicant treats this
scenario.
If a commit is received while in an accepted state the spec states
the scalar should be checked against the previous commit and if
equal the message should be silently dropped.
The hwsim rules did not treat frames and ACKs any differently which
can mislead the developer especially when setting a rule prefix.
If a prefix was used the frame ACK was actually being matched against
the original frame payload which seems wrong because the ACK is not
the original frame.
Though strange, matching the frame prefix on an ACK has its place if
the developer wants to block just the ACK rather than the frame so
to make this case more clear 'DropAck' was added as a rule property.
And only if this is true will an ACK be checked and potentially
dropped.
To maintain the current hwsim behavior DropAck will default to true.
