Re: [PATCH net-next] tls: Add support for inplace records encryption

[David Miller <davem@davemloft.net>]

From: Vakul Garg <vakul.garg@nxp.com>
Date: Sun, 30 Sep 2018 08:04:35 +0530

> Presently, for non-zero copy case, separate pages are allocated for
> storing plaintext and encrypted text of records. These pages are stored
> in sg_plaintext_data and sg_encrypted_data scatterlists inside record
> structure. Further, sg_plaintext_data & sg_encrypted_data are passed
> to cryptoapis for record encryption. Allocating separate pages for
> plaintext and encrypted text is inefficient from both required memory
> and performance point of view.
> 
> This patch adds support of inplace encryption of records. For non-zero
> copy case, we reuse the pages from sg_encrypted_data scatterlist to
> copy the application's plaintext data. For the movement of pages from
> sg_encrypted_data to sg_plaintext_data scatterlists, we introduce a new
> function move_to_plaintext_sg(). This function add pages into
> sg_plaintext_data from sg_encrypted_data scatterlists.
> 
> tls_do_encryption() is modified to pass the same scatterlist as both
> source and destination into aead_request_set_crypt() if inplace crypto
> has been enabled. A new ariable 'inplace_crypto' has been introduced in
> record structure to signify whether the same scatterlist can be used.
> By default, the inplace_crypto is enabled in get_rec(). If zero-copy is
> used (i.e. plaintext data is not copied), inplace_crypto is set to '0'.
> 
> Signed-off-by: Vakul Garg <vakul.garg@nxp.com>

Applied.