Re: [PATCH 15/15] wifi: mac80211: Use AES-CMAC library in aes_s2v()

[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 aes_s2v() to use it instead
> of a "cmac(aes)" crypto_shash.  The result is faster and simpler code.
> 
> It's also more reliable, since with the library the only step that can
> fail is preparing the key.  In contrast, crypto_shash_digest(),
> crypto_shash_init(), crypto_shash_update(), and crypto_shash_final()
> could all fail and return an errno value.  aes_s2v() ignored these
> errors, which was a bug.  So that bug is fixed as well.
> 
> As part of this, change the prototype of aes_s2v() to take the raw key
> directly instead of a prepared key.  Its only two callers prepare a key
> for each call, so it might as well be done directly in aes_s2v().
> 
> Since this removes the last dependency on the "cmac(aes)" crypto_shash
> from mac80211, also remove the 'select CRYPTO_CMAC'.
> 



> -static int aes_s2v(struct crypto_shash *tfm,
> +static int aes_s2v(const u8 *in_key, size_t key_len,
>  		   size_t num_elem, const u8 *addr[], size_t len[], u8 *v)
>  {
>  	u8 d[AES_BLOCK_SIZE], tmp[AES_BLOCK_SIZE] = {};
> -	SHASH_DESC_ON_STACK(desc, tfm);
> +	struct aes_cmac_key key;
> +	struct aes_cmac_ctx ctx;
>  	size_t i;
> +	int res;
>  
> -	desc->tfm = tfm;
> +	res = aes_cmac_preparekey(&key, in_key, key_len);
> +	if (res)
> +		return res;

Same here, maybe, technically, but also doesn't matter.

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

johannes