[PATCH v2 0/2] Add SM4 XTS symmetric algorithm for blk-crypto and fscrypt

[PATCH v2 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.
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.

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 v2 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, 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)

[PATCH v2 2/2] fscrypt: Add SM4 XTS/CTS symmetric algorithm support

[Tianjia Zhang]

SM4 is a symmetric algorithm widely used in China, 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 v2 2/2] fscrypt: Add SM4 XTS/CTS symmetric algorithm support

[Eric Biggers]

On Tue, Nov 22, 2022 at 03:06:32PM +0800, Tianjia Zhang wrote:
> SM4 is a symmetric algorithm widely used in China, 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>

There is still no explanation here about why you believe this algorithm is
useful to support in fscrypt.

- Eric

Re: [PATCH v2 2/2] fscrypt: Add SM4 XTS/CTS symmetric algorithm support

[Tianjia Zhang]

Hi Eric,

On 11/23/22 3:22 AM, Eric Biggers wrote:
> On Tue, Nov 22, 2022 at 03:06:32PM +0800, Tianjia Zhang wrote:
>> SM4 is a symmetric algorithm widely used in China, 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>
> 
> There is still no explanation here about why you believe this algorithm is
> useful to support in fscrypt.
> 
> - Eric

Sorry, I will send a new version of patch to add these information.

Best regards,
Tianjia