Re: [PATCH v3 1/2] blk-crypto: Add support for SM4-XTS blk crypto mode

[Eric Biggers]

On Fri, Nov 25, 2022 at 08:16:29PM +0800, Tianjia Zhang wrote:
> SM4 is a symmetric algorithm widely used in China, and SM4-XTS is also
> used to encrypt length-preserving data, these algoritms are mandatory
> in many scenarios. This patch enables the use of SM4-XTS algorithm in
> block inline encryption, and provides support for fscrypt.
> 
> Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
> ---
>  block/blk-crypto.c         | 6 ++++++
>  include/linux/blk-crypto.h | 1 +
>  2 files changed, 7 insertions(+)
> 
> diff --git a/block/blk-crypto.c b/block/blk-crypto.c
> index a496aaef85ba..e44709fc6a08 100644
> --- a/block/blk-crypto.c
> +++ b/block/blk-crypto.c
> @@ -36,6 +36,12 @@ const struct blk_crypto_mode blk_crypto_modes[] = {
>  		.keysize = 32,
>  		.ivsize = 32,
>  	},
> +	[BLK_ENCRYPTION_MODE_SM4_XTS] = {
> +		.name = "SM4-XTS",
> +		.cipher_str = "xts(sm4)",
> +		.keysize = 32,
> +		.ivsize = 16,
> +	},
>  };
>  
>  /*
> diff --git a/include/linux/blk-crypto.h b/include/linux/blk-crypto.h
> index 69b24fe92cbf..26b1b71c3091 100644
> --- a/include/linux/blk-crypto.h
> +++ b/include/linux/blk-crypto.h
> @@ -13,6 +13,7 @@ enum blk_crypto_mode_num {
>  	BLK_ENCRYPTION_MODE_AES_256_XTS,
>  	BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV,
>  	BLK_ENCRYPTION_MODE_ADIANTUM,
> +	BLK_ENCRYPTION_MODE_SM4_XTS,
>  	BLK_ENCRYPTION_MODE_MAX,

The commit message should mention that this is needed for the inlinecrypt mount
option to be supported via blk-crypto-fallback, as it is for the other fscrypt
modes.  (Since there's no inline encryption hardware that supports SM4-XTS.)

Anyway, if SM4-XTS support is really being added to fscrypt, then this patch
looks fine.  Jens, are you okay with me taking it through the fscrypt tree?

- Eric