Re: [PATCH v3 2/2] fscrypt: Add SM4 XTS/CTS symmetric algorithm support

[Eric Biggers]

On Fri, Nov 25, 2022 at 08:16:30PM +0800, Tianjia Zhang wrote:
> diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
> index 46757c3052ef..8e69bc0c35cd 100644
> --- a/fs/crypto/policy.c
> +++ b/fs/crypto/policy.c
> @@ -71,6 +71,10 @@ static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode)
>  	    filenames_mode == FSCRYPT_MODE_AES_128_CTS)
>  		return true;
>  
> +	if (contents_mode == FSCRYPT_MODE_SM4_XTS &&
> +	    filenames_mode == FSCRYPT_MODE_SM4_CTS)
> +		return true;
> +
>  	if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
>  	    filenames_mode == FSCRYPT_MODE_ADIANTUM)
>  		return true;

Sorry, one more thing I didn't notice before.  Since this is a new feature,
please only allow it in fscrypt_valid_enc_modes_v2(), not in
fscrypt_valid_enc_modes_v1().  That's what we did for AES-256-XTS +
AES-256-HCTR2 recently.  There should be no need to add new features to
v1 encryption policies, which have been deprecated for several years.

- Eric