netdev - Re: [PATCH net-next v1 5/7] net/handshake: Add helpers for parsing incoming TLS Alerts

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Message-ID: <8c9399d8-1f2e-5da0-28c2-722f382a5a08@suse.de>
Date: Wed, 19 Jul 2023 09:52:21 +0200
From: Hannes Reinecke <hare@...e.de>
To: Chuck Lever <cel@...nel.org>, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com
Cc: netdev@...r.kernel.org, kernel-tls-handshake@...ts.linux.dev
Subject: Re: [PATCH net-next v1 5/7] net/handshake: Add helpers for parsing
 incoming TLS Alerts

On 7/18/23 21:00, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@...cle.com>
> 
> Kernel TLS consumers can replace common TLS Alert parsing code with
> these helpers.
> 
> Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
> ---
>   include/net/handshake.h |    4 ++++
>   net/handshake/alert.c   |   46 ++++++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 50 insertions(+)
> 
> diff --git a/include/net/handshake.h b/include/net/handshake.h
> index bb88dfa6e3c9..d0fd6a3898c6 100644
> --- a/include/net/handshake.h
> +++ b/include/net/handshake.h
> @@ -42,4 +42,8 @@ int tls_server_hello_psk(const struct tls_handshake_args *args, gfp_t flags);
>   bool tls_handshake_cancel(struct sock *sk);
>   void tls_handshake_close(struct socket *sock);
>   
> +u8 tls_record_type(const struct sock *sk, const struct cmsghdr *msg);
> +bool tls_alert_recv(const struct sock *sk, const struct msghdr *msg,
> +		    u8 *level, u8 *description);
> +
>   #endif /* _NET_HANDSHAKE_H */
> diff --git a/net/handshake/alert.c b/net/handshake/alert.c
> index 999d3ffaf3e3..93e05d8d599c 100644
> --- a/net/handshake/alert.c
> +++ b/net/handshake/alert.c
> @@ -60,3 +60,49 @@ int tls_alert_send(struct socket *sock, u8 level, u8 description)
>   	ret = sock_sendmsg(sock, &msg);
>   	return ret < 0 ? ret : 0;
>   }
> +
> +/**
> + * tls_record_type - Look for TLS RECORD_TYPE information
> + * @sk: socket (for IP address information)
> + * @cmsg: incoming message to be parsed
> + *
> + * Returns zero or a TLS_RECORD_TYPE value.
> + */
> +u8 tls_record_type(const struct sock *sk, const struct cmsghdr *cmsg)
> +{
> +	u8 record_type;
> +
> +	if (cmsg->cmsg_level != SOL_TLS)
> +		return 0;
> +	if (cmsg->cmsg_type != TLS_GET_RECORD_TYPE)
> +		return 0;
> +
> +	record_type = *((u8 *)CMSG_DATA(cmsg));
> +	return record_type;
> +}
> +EXPORT_SYMBOL(tls_record_type);
> +
tls_process_cmsg() does nearly the same thing; why didn't you update it 
to use your helper?

> +/**
> + * tls_alert_recv - Look for TLS Alert messages
> + * @sk: socket (for IP address information)
> + * @msg: incoming message to be parsed
> + * @level: OUT - TLS AlertLevel value
> + * @description: OUT - TLS AlertDescription value
> + *
> + * Return values:
> + *   %true: @msg contained a TLS Alert; @level and @description filled in
> + *   %false: @msg did not contain a TLS Alert
> + */
> +bool tls_alert_recv(const struct sock *sk, const struct msghdr *msg,
> +		    u8 *level, u8 *description)
> +{
> +	const struct kvec *iov;
> +	u8 *data;
> +
> +	iov = msg->msg_iter.kvec;
> +	data = iov->iov_base;
> +	*level = data[0];
> +	*description = data[1];
> +	return true;
> +}
> +EXPORT_SYMBOL(tls_alert_recv);
> 
Shouldn't we check the type of message here?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@...e.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Frankenstr. 146, 90461 Nürnberg
Managing Directors: I. Totev, A. Myers, A. McDonald, M. B. Moerman
(HRB 36809, AG Nürnberg)