[PATCH 1/2] nl80211: Retrieve maxattr via genl for nl80211

[Benjamin Berg]

Hi,

On Sun, 2024-01-14 at 18:23 +0200, Jouni Malinen wrote:
> On Thu, Dec 28, 2023 at 03:14:05PM +0200, Andrei Otcheretianski
> wrote:
> > Older kernel versions may not support all attributes and may refuse
> > commands that include them. To avoid sending too new attributes
> > query
> > the highest supported attribute. This allows adding appropriate
> > checks
> > where needed.
> 
> Thanks, both patches applied.
> 
> Are the two cases in patch 2/2 all the known issues or are there some
> other known cases that could fail with older kernel versions?

Those were the only obvious places that I saw when looking over it a
while ago.

That said, Johannes recently mentioned that commit 6cc78b3945d3271a
("nl80211: Set NL80211_WPA_VERSION_2 vs. _3 based on AKM") is
problematic on older kernel versions that might not understand the new
value.

Unfortunately, in that case there is no way to directly check for the
support. However, he did say that we could check for the related
NL80211_ATTR_SAE_PASSWORD as a heuristic to know whether
NL80211_WPA_VERSION_3 is supported by the kernel.

Benjamin