Re: [PATCH net-next v3 2/6] tls: block decryption when a rekey is pending

From: Jakub Kicinski <kuba@kernel.org>
To: Sabrina Dubroca <sd@queasysnail.net>
Cc: netdev@vger.kernel.org, Vadim Fedorenko <vfedorenko@novek.ru>,
	Frantisek Krenzelok <fkrenzel@redhat.com>,
	Kuniyuki Iwashima <kuniyu@amazon.com>,
	Apoorv Kothari <apoorvko@amazon.com>,
	Boris Pismenny <borisp@nvidia.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Shuah Khan <shuah@kernel.org>,
	linux-kselftest@vger.kernel.org, Gal Pressman <gal@nvidia.com>,
	Marcel Holtmann <marcel@holtmann.org>
Subject: Re: [PATCH net-next v3 2/6] tls: block decryption when a rekey is pending
Date: Fri, 11 Aug 2023 18:37:53 -0700	[thread overview]
Message-ID: <20230811183753.3a18a09a@kernel.org> (raw)
In-Reply-To: <eae51cdb1d15c914577a88fb5cd9d1c4b1121642.1691584074.git.sd@queasysnail.net>

On Wed,  9 Aug 2023 14:58:51 +0200 Sabrina Dubroca wrote:
> +static int tls_check_pending_rekey(struct sock *sk, struct sk_buff *skb)
> +{
> +	const struct tls_msg *tlm = tls_msg(skb);
> +	const struct strp_msg *rxm = strp_msg(skb);
> +
> +	if (tlm->control == TLS_RECORD_TYPE_HANDSHAKE) {

unlikely()

does the nachine code look worse if we flip the condition and return
early instead of indenting the entire function?

> +		char hs_type;
> +		int err;

I'd probably err on the side of declaring those on the outside, but if
we don't we should move rxm in here, it's not needed outside. Either,
or.

> +		if (rxm->full_len < 1)
> +			return -EINVAL;
> +
> +		err = skb_copy_bits(skb, rxm->offset, &hs_type, 1);
> +		if (err < 0)
> +			return err;
> +
> +		if (hs_type == TLS_HANDSHAKE_KEYUPDATE) {
> +			struct tls_context *ctx = tls_get_ctx(sk);

feels a bit like we should just pass ctx rather than sk?

> +			struct tls_sw_context_rx *rx_ctx = ctx->priv_ctx_rx;
> +
> +			rx_ctx->key_update_pending = true;
> +		}
> +	}
> +
> +	return 0;
> +}