Subject: Re: [PATCH net-next 10/12] tls/sw: Convert tls_sw_sendpage() to use MSG_SPLICE_PAGES

From: Jakub Kicinski <[email-masked]>
Date: Fri, 26 May 2023 18:13:38 -0700

On Wed, 24 May 2023 16:33:09 +0100 David Howells wrote:
> Convert tls_sw_sendpage() and tls_sw_sendpage_locked() to use sendmsg()
> with MSG_SPLICE_PAGES rather than directly splicing in the pages itself.
> 
> [!] Note that tls_sw_sendpage_locked() appears to have the wrong locking
>     upstream.  I think the caller will only hold the socket lock, but it
>     should hold tls_ctx->tx_lock too.

Lock ordering, as you probably discovered. It is what it is :|

> +	if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
> +			       MSG_CMSG_COMPAT | MSG_SPLICE_PAGES |
> +			       MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY))
> +		return -EOPNOTSUPP;

Now MSG_SENDPAGE_* can leak in thru the sendmsg() call?
Letting MSG_SENDPAGE_NOPOLICY in seems pretty suspicious, no?