Re: [PATCH v2 1/4] knownnetworks: network: support updating known network settings

James Prestwood
2023-12-19T12:57:29Z

Hi Denis,

On 12/18/23 8:31 PM, Denis Kenzior wrote:
> Hi James,
>
> On 12/18/23 08:12, James Prestwood wrote:
>> Currently if a known network is modified on disk the settings are not
>> reloaded by network. Only disconnecting/reconnecting to the network
>> would update the settings. This poses an issue to DPP since its
>> creating or updating a known network after configuration then trying
>> to connect. The connection itself works fine since the PSK/passphrase
>> is set to the network object directly, but any additional settings
>> are not updated.
>>
>> To fix this add a new UPDATED known network event. This is then
>> handled from within network and all settings read from disk are
>> applied to the network object.
>> ---
>>   src/knownnetworks.c |  4 ++++
>>   src/knownnetworks.h |  1 +
>>   src/network.c       | 27 ++++++++++++++++++++++++---
>>   3 files changed, 29 insertions(+), 3 deletions(-)
>>
>> v2:
>>   * Instead of bothering with individual settings we can just use the
>>     new l_settings object. This would still prefer agent-obtained creds
>>     set into the network object but also honor any new settings written
>
> Ehh, I'm not so sure about this. handshake_state_set_8021x_config()
> does a shallow copy of the l_settings object.  I think eap state
> machine will make copies of the info it needs, but...
Ok, yes this wouldn't work as-is then, but we could clone it instead.
>
>>     to the profile if there is an ongoing connection. This is a much
>>     simpler approach (unless I'm missing something). Only questionable
>
> Also, netconfig_load_settings is called very early in
> __station_connect_network, so even if you overwrite the settings
> object here, it is probably too late to take any effect.

For this case I'm not sure there is any difference. Keeping the existing
settings or replacing won't change netconfig once
__station_connect_network() is called. We would need some changes in
station to load the settings again after the connection. I'm not sure
trying to solve this specific case of settings changing _during_ a
connection is really in the scope of this patch set. I'm also not really
convinced trying to fix this race condition is all that important. Its
not really a "race" per-se, but more of just how IWD works. The profile
is loaded upon connecting and those settings are used. If you swap
out/modify the profile in the middle of that I don't think anyone
would/should expect those changes to be taken for that ongoing
connection. That's my opinion on it anyways.

What we do need is the ability to update settings on disk if IWD is
sitting idle or connected. Currently if network/network->settings
already exists its not possible to update unless IWD disconnects.

You mentioned copying over all settings except the security group, but
this wouldn't handle the case of DPP (or anything) updating the profile
with new credentials. I think we need the l_settings object to be 100%
synced with whats on disk (but as you said,
network->psk/network->passphrase shouldn't be altered). This then means
the entire settings is copied, so its much more efficient to just
replace it. Does this make sense?

Thanks,

James

>
>>     piece is what to do with the Security group. I hesitate to skip it
>>     because its what we have on disk, but it could mean the network
>>     object isn't synced with its settings. But I'm not sure this is
>>     any different than what we have today, if a profile is modified
>>     during an ongoing connection its settings (including security)
>>     won't get updated until a disconnect/reconnect.
>>
>>   * Remove frequency sync on UPDATED event
>>
>
> Regards,
> -Denis
>