Re: [PATCH 14/15] wifi: mac80211: Use AES-CMAC library in ieee80211_aes_cmac()

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2026-02-18 at 13:35 -0800, Eric Biggers wrote:
> Now that AES-CMAC has a library API, convert the mac80211 AES-CMAC
> packet authentication code to use it instead of a "cmac(aes)"
> crypto_shash.  This has multiple benefits, such as:
> 
> - It's faster.  The AES-CMAC code is now called directly, without
>   unnecessary overhead such as indirect calls.
> 
> - MAC calculation can no longer fail.
> 
> - The AES-CMAC key struct is now a fixed size, allowing it to be
>   embedded directly into 'struct ieee80211_key' rather than using a
>   separate allocation.  Note that although this increases the size of
>   the 'u.cmac' field of 'struct ieee80211_key', it doesn't cause it to
>   exceed the size of the largest variant of the union 'u'.  Therefore,
>   the size of 'struct ieee80211_key' itself is unchanged.
> 

Looks good to me in principle, I suppose we should test it? :)

> +		err = aes_cmac_preparekey(&key->u.aes_cmac.key, key_data,
> +					  key_len);
> +		if (err) {
>  			kfree(key);
>  			return ERR_PTR(err);
>  		}

Pretty sure that can't fail, per the documentation for
aes_prepareenckey() and then aes_cmac_preparekey(), but it doesn't
really matter. We can only get here with a key with size checked by
cfg80211_validate_key_settings() already.


Since you're probably going to send it through the crypto tree:

Acked-by: Johannes Berg <johannes@sipsolutions.net>

johannes