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

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Date:   Mon, 28 Nov 2022 15:35:37 +0800
From:   Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     "Theodore Y. Ts o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Jonathan Corbet <corbet@....net>, Jens Axboe <axboe@...nel.dk>,
        Ard Biesheuvel <ardb@...nel.org>,
        linux-fscrypt@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v3 2/2] fscrypt: Add SM4 XTS/CTS symmetric algorithm
 support

Hi Eric,

On 11/26/22 2:24 AM, Eric Biggers wrote:
> 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

Thanks for reminder, it makes sense to only support the new algorithm in
v2 policy, which I will do this.

BR,
Tianjia