Re: [PATCH] rt61pci: Work around a firmware bug with shared keys

[Stanislaw Gruszka]

On Tue, Jan 15, 2019 at 02:01:29PM +0000, Bernd Edlinger wrote:
> Apparently the rt2x61 firmware fails temporarily to decode
> broadcast packets if the shared keys are not assigned
> in the "correct" sequence. At the same time unicast
> packets work fine, since they are encrypted with the
> pairwise key.
> 
> At least with WPA2 CCMP mode the shared keys are
> set in the following sequence: keyidx=1, 2, 1, 2.
> After a while only keyidx 2 gets decrypted, and
> keyidx 1 is ignored, probably because there is never
> a keyidx 3.
> 
> Symptoms are arping -b works for 10 minutes, since
> keyidx=2 is used for broadcast, and then it stops
> working for 10 minutes, because keyidx=1 is used.
> That failure mode repeats forever.
> 
> Note, the firmware does not even know which keyidx
> corresponds to which hw_key_idx so the firmware is
> trying to be smarter than the driver, which is bound
> to fail.
> 
> As workaround the function rt61pci_config_shared_key
> requests software decryption of the shared keys,
> by returning EOPNOTSUPP. However, pairwise keys are
> still handled by hardware which works just fine.
> 
> Signed-off-by: Bernd Edlinger <bernd.edlinger@xxxxxxxxxx>

Acked-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>