[PATCH v3 0/2] Add SM4 XTS symmetric algorithm for blk-crypto and fscrypt

[PATCH v3 0/2] Add SM4 XTS symmetric algorithm for blk-crypto and fscrypt

[Tianjia Zhang]

SM4 is widely used in China's data encryption software and hardware.
these algoritms are mandatory in many scenarios. This serial of
patches enables the SM4-XTS algorithm in blk-crypto and enables the
SM4-XTS/CTS algorithm in fscrypt to encrypt file content and filename.

v3 change:
  - update git commit message

v2 change:
  - As Eric said, the new FSCRYPT_MODE is defined for the unused numbers 7 and 8

Tianjia Zhang (2):
  blk-crypto: Add support for SM4-XTS blk crypto mode
  fscrypt: Add SM4 XTS/CTS symmetric algorithm support

 Documentation/filesystems/fscrypt.rst |  1 +
 block/blk-crypto.c                    |  6 ++++++
 fs/crypto/keysetup.c                  | 15 +++++++++++++++
 fs/crypto/policy.c                    |  4 ++++
 include/linux/blk-crypto.h            |  1 +
 include/uapi/linux/fscrypt.h          |  2 ++
 6 files changed, 29 insertions(+)

-- 
2.24.3 (Apple Git-128)

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

[Tianjia Zhang]

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@linux.alibaba.com>
---
 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,
 };
 
-- 
2.24.3 (Apple Git-128)

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@linux.alibaba.com>
> ---
>  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

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

[Jens Axboe]

On 11/25/22 11:35 AM, Eric Biggers wrote:
> 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@linux.alibaba.com>
>> ---
>>  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?

Yes, go ahead.

-- 
Jens Axboe

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

[Bagas Sanjaya]

On 11/25/22 19:16, 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.
> 

Please reformulate the patch description in imperative mood instead.
Also, take care of wording and punctuation - commas should not be
used for continuing distinct sentences/clauses where separating them
by a full stop is more appropriate.

That is, the description should be:

```
SM4 is a symmetric cipher algorithm widely used in China. The SM4-XTS
variant is used to encrypt length-preserving data.

Enable the algorithm in block inline encryption, as well as enable
fscrypt support.
```

Thanks.

-- 
An old man doll... just what I always wanted! - Clara

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

[Tianjia Zhang]

SM4 is a symmetric algorithm widely used in China, and is even mandatory
in many scenarios. We need to provide these users with the ability to
encrypt files or disks using SM4-XTS, and many other algorithms that use
SM2/3/4 algorithms or their combined algorithm scenarios, these features
are demanded by many users, this patch enables to use SM4-XTS mode to
encrypt file content, and use SM4-CBC-CTS to encrypt filename.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
---
 Documentation/filesystems/fscrypt.rst |  1 +
 fs/crypto/keysetup.c                  | 15 +++++++++++++++
 fs/crypto/policy.c                    |  4 ++++
 include/uapi/linux/fscrypt.h          |  2 ++
 4 files changed, 22 insertions(+)

diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 5ba5817c17c2..af27e7b2c74f 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -336,6 +336,7 @@ Currently, the following pairs of encryption modes are supported:
 
 - AES-256-XTS for contents and AES-256-CTS-CBC for filenames
 - AES-128-CBC for contents and AES-128-CTS-CBC for filenames
+- SM4-XTS for contents and SM4-CTS-CBC for filenames
 - Adiantum for both contents and filenames
 - AES-256-XTS for contents and AES-256-HCTR2 for filenames (v2 policies only)
 
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index f7407071a952..24e55c95abc3 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -44,6 +44,21 @@ struct fscrypt_mode fscrypt_modes[] = {
 		.security_strength = 16,
 		.ivsize = 16,
 	},
+	[FSCRYPT_MODE_SM4_XTS] = {
+		.friendly_name = "SM4-XTS",
+		.cipher_str = "xts(sm4)",
+		.keysize = 32,
+		.security_strength = 16,
+		.ivsize = 16,
+		.blk_crypto_mode = BLK_ENCRYPTION_MODE_SM4_XTS,
+	},
+	[FSCRYPT_MODE_SM4_CTS] = {
+		.friendly_name = "SM4-CTS",
+		.cipher_str = "cts(cbc(sm4))",
+		.keysize = 16,
+		.security_strength = 16,
+		.ivsize = 16,
+	},
 	[FSCRYPT_MODE_ADIANTUM] = {
 		.friendly_name = "Adiantum",
 		.cipher_str = "adiantum(xchacha12,aes)",
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;
diff --git a/include/uapi/linux/fscrypt.h b/include/uapi/linux/fscrypt.h
index a756b29afcc2..47dbd1994bfe 100644
--- a/include/uapi/linux/fscrypt.h
+++ b/include/uapi/linux/fscrypt.h
@@ -26,6 +26,8 @@
 #define FSCRYPT_MODE_AES_256_CTS		4
 #define FSCRYPT_MODE_AES_128_CBC		5
 #define FSCRYPT_MODE_AES_128_CTS		6
+#define FSCRYPT_MODE_SM4_XTS			7
+#define FSCRYPT_MODE_SM4_CTS			8
 #define FSCRYPT_MODE_ADIANTUM			9
 #define FSCRYPT_MODE_AES_256_HCTR2		10
 /* If adding a mode number > 10, update FSCRYPT_MODE_MAX in fscrypt_private.h */
-- 
2.24.3 (Apple Git-128)

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

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

[Tianjia Zhang]

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

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

[Bagas Sanjaya]

On 11/25/22 19:16, Tianjia Zhang wrote:
> SM4 is a symmetric algorithm widely used in China, and is even mandatory
> in many scenarios. We need to provide these users with the ability to
> encrypt files or disks using SM4-XTS, and many other algorithms that use
> SM2/3/4 algorithms or their combined algorithm scenarios, these features
> are demanded by many users, this patch enables to use SM4-XTS mode to
> encrypt file content, and use SM4-CBC-CTS to encrypt filename.
> 

Similar reply as [1]. That is, better say:

```
Add support for XTS and CTS mode variant of SM4 algorithm, in similar
fashion to SM2 and SM3. The former is used to encrypt file contents, while
the latter (SM4-CBC-CTS) is used to encrypt filenames. 
```

Thanks.

[1]: https://lore.kernel.org/linux-doc/42624542-6ccb-26a5-db98-d7944972246e@gmail.com/

-- 
An old man doll... just what I always wanted! - Clara

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

[Tianjia Zhang]

Hi Bagas,

On 11/28/22 9:33 PM, Bagas Sanjaya wrote:
> On 11/25/22 19:16, Tianjia Zhang wrote:
>> SM4 is a symmetric algorithm widely used in China, and is even mandatory
>> in many scenarios. We need to provide these users with the ability to
>> encrypt files or disks using SM4-XTS, and many other algorithms that use
>> SM2/3/4 algorithms or their combined algorithm scenarios, these features
>> are demanded by many users, this patch enables to use SM4-XTS mode to
>> encrypt file content, and use SM4-CBC-CTS to encrypt filename.
>>
> 
> Similar reply as [1]. That is, better say:
> 
> ```
> Add support for XTS and CTS mode variant of SM4 algorithm, in similar
> fashion to SM2 and SM3. The former is used to encrypt file contents, while
> the latter (SM4-CBC-CTS) is used to encrypt filenames.
> ```
> 
> Thanks.
> 
> [1]: https://lore.kernel.org/linux-doc/42624542-6ccb-26a5-db98-d7944972246e@gmail.com/
> 

Thanks for your reply, it is very valuable for me, I will update it in
the next patch.

Cheers,
Tianjia