netdev - Re: [PATCH 6/6] net/tls: implement ->read

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Message-ID: <a3184117-751a-c582-6295-f45a26398deb@suse.de>
Date: Fri, 21 Jul 2023 15:53:05 +0200
From: Hannes Reinecke <hare@...e.de>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
 Keith Busch <kbusch@...nel.org>, linux-nvme@...ts.infradead.org,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 netdev@...r.kernel.org, Boris Pismenny <boris.pismenny@...il.com>
Subject: Re: [PATCH 6/6] net/tls: implement ->read_sock()

On 7/21/23 05:02, Jakub Kicinski wrote:
> On Wed, 19 Jul 2023 13:38:36 +0200 Hannes Reinecke wrote:
>> Implement ->read_sock() function for use with nvme-tcp.
> 
>> +int tls_sw_read_sock(struct sock *sk, read_descriptor_t *desc,
>> +		     sk_read_actor_t read_actor)
>> +{
>> +	struct tls_context *tls_ctx = tls_get_ctx(sk);
>> +	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
>> +	struct strp_msg *rxm = NULL;
>> +	struct tls_msg *tlm;
>> +	struct sk_buff *skb;
>> +	struct sk_psock *psock;
>> +	ssize_t copied = 0;
>> +	bool bpf_strp_enabled;
> 
> bubble up the longer lines, like this:
> 
> +	struct tls_context *tls_ctx = tls_get_ctx(sk);
> +	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
> +	struct strp_msg *rxm = NULL;
> +	struct sk_psock *psock;
> +	bool bpf_strp_enabled;
> +	struct tls_msg *tlm;
> +	struct sk_buff *skb;
> +	ssize_t copied = 0;
> +	int err, used;
> 
Ok.

>> +	int err, used;
>> +
>> +	psock = sk_psock_get(sk);
>> +	err = tls_rx_reader_acquire(sk, ctx, true);
>> +	if (err < 0)
>> +		goto psock_put;
>> +	bpf_strp_enabled = sk_psock_strp_enabled(psock);
> 
> You're not servicing the BPF out of band queue, just error out if
> the BPF psock is enabled. It's barely used and endlessly buggy anyway.
> 
Have been wondering about that; will do.

>> +	/* If crypto failed the connection is broken */
>> +	err = ctx->async_wait.err;
>> +	if (err)
>> +		goto read_sock_end;
>> +
>> +	do {
>> +		if (!skb_queue_empty(&ctx->rx_list)) {
>> +			skb = __skb_dequeue(&ctx->rx_list);
>> +			rxm = strp_msg(skb);
>> +		} else {
>> +			struct tls_decrypt_arg darg;
>> +
>> +			err = tls_rx_rec_wait(sk, psock, true, true);
>> +			if (err <= 0)
>> +				goto read_sock_end;
>> +
>> +			memset(&darg.inargs, 0, sizeof(darg.inargs));
>> +			darg.zc = !bpf_strp_enabled && ctx->zc_capable;
> 
> And what are you zero-copying into my friend? zc == zero copy.
> Leave the zc be 0, like splice does, otherwise passing msg=NULL
> to tls_rx_one_record() may explode. Testing with TLS 1.2 should
> show that.
> 
Still beginning to learn how the stream parser works.
(And have been wondering about the 'msg == NULL' case, too).
Will fix it.

>> +			rxm = strp_msg(tls_strp_msg(ctx));
>> +			tlm = tls_msg(tls_strp_msg(ctx));
>> +
>> +			/* read_sock does not support reading control messages */
>> +			if (tlm->control != TLS_RECORD_TYPE_DATA) {
>> +				err = -EINVAL;
>> +				goto read_sock_requeue;
>> +			}
>> +
>> +			if (!bpf_strp_enabled)
>> +				darg.async = ctx->async_capable;
>> +			else
>> +				darg.async = false;
> 
> Also don't bother with async. TLS 1.3 can't do async, anyway,
> and I don't think you wait for the completion :S
> 
Ok.

>> +			err = tls_rx_one_record(sk, NULL, &darg);
>> +			if (err < 0) {
>> +				tls_err_abort(sk, -EBADMSG);
>> +				goto read_sock_end;
>> +			}
>> +
>> +			sk_flush_backlog(sk);
> 
> Hm, could be a bit often but okay.
> 
When would you suggest to do it?
(Do I need to do it at all?)

>> +			skb = darg.skb;
>> +			rxm = strp_msg(skb);
>> +
>> +			tls_rx_rec_done(ctx);
>> +		}
>> +
>> +		used = read_actor(desc, skb, rxm->offset, rxm->full_len);
>> +		if (used <= 0) {
>> +			if (!copied)
>> +				err = used;
>> +			goto read_sock_end;
> 
> You have to requeue on error.
> 
Ah, right. Did it in the previous version, but somehow got
lost here.

Will be fixing it up.

>> +		}
>> +		copied += used;
>> +		if (used < rxm->full_len) {
>> +			rxm->offset += used;
>> +			rxm->full_len -= used;
>> +			if (!desc->count)
>> +				goto read_sock_requeue;
> 
> And here. Like splice_read does. Otherwise you leak the skb.
> 
Will do.

Thanks for the review!

Cheers,

Hannes