Re: [PATCH 07/11] sae: support reception of Confirm frame by AP

[James Prestwood <prestwoj@gmail.com>]

Hi John,

On 4/21/24 5:50 AM, John Brandt wrote:
> Experimental AP-mode support for receiving a Confirm frame when in the
> COMMITTED state. The AP will reply with a Confirm frame.
>
> Note that when acting as an AP, on reception of a Commit frame, the AP
> only replies with a Commit frame. The protocols allows to also already
> send the Confirm frame, but older clients may not support simultaneously
> receiving a Commit and Confirm frame.
Could we add some basic unit tests. Mainly just sanity checks that the 
message flow works as expected with handshake->authenticator set.
> ---
>   src/sae.c | 38 +++++++++++++++++++++++++-------------
>   1 file changed, 25 insertions(+), 13 deletions(-)
>
> diff --git a/src/sae.c b/src/sae.c
> index 8a1e311a..da55c764 100644
> --- a/src/sae.c
> +++ b/src/sae.c
> @@ -906,9 +906,13 @@ static int sae_process_confirm(struct sae_sm *sm, const uint8_t *from,
>   
>   	sm->state = SAE_STATE_ACCEPTED;
>   
> -	sae_debug("Sending Associate to "MAC, MAC_STR(sm->handshake->aa));
> -
> -	sm->tx_assoc(sm->user_data);
> +	if (!sm->handshake->authenticator) {
> +		sae_debug("Sending Associate to "MAC, MAC_STR(sm->handshake->aa));
> +		sm->tx_assoc(sm->user_data);
> +	} else {
> +		if (!sae_send_confirm(sm))
> +			return -EPROTO;
> +	}
>   
>   	return 0;
>   }
> @@ -1059,16 +1063,24 @@ static int sae_verify_committed(struct sae_sm *sm, uint16_t transaction,
>   	unsigned int skip;
>   	struct ie_tlv_iter iter;
>   
> -	/*
> -	 * Upon receipt of a Con event...
> -	 * Then the protocol instance checks the value of Sync. If it
> -	 * is greater than dot11RSNASAESync, the protocol instance shall send a
> -	 * Del event to the parent process and transition back to Nothing state.
> -	 * If Sync is not greater than dot11RSNASAESync, the protocol instance
> -	 * shall increment Sync, transmit the last SAE Commit message sent to
> -	 * the peer...
> -	 */
> -	if (transaction == SAE_STATE_CONFIRMED) {
> +	if (sm->handshake->authenticator && transaction == SAE_STATE_CONFIRMED) {
> +		/*
> +		 * TODO: Sanity-check received Confirm frame from the client. For now
> +		 * AP-mode SAE support is experimental and we simply accept the frame.
> +		 * Note that the cryptographic confirm field value will still be checked
> +		 * before replying with a Confirm frame.
> +		 */
> +		return 0;
> +	} else if (transaction == SAE_STATE_CONFIRMED) {
> +		/*
> +		 * Upon receipt of a Con event...
> +		 * Then the protocol instance checks the value of Sync. If it
> +		 * is greater than dot11RSNASAESync, the protocol instance shall send a
> +		 * Del event to the parent process and transition back to Nothing state.
> +		 * If Sync is not greater than dot11RSNASAESync, the protocol instance
> +		 * shall increment Sync, transmit the last SAE Commit message sent to
> +		 * the peer...
> +		 */
>   		if (sm->sync > SAE_SYNC_MAX)
>   			return -ETIMEDOUT;
>