[PATCH v6 11/17] soc: qcom: ice: add support for generating, importing and preparing keys

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Gaurav Kashyap <quic_gaurkash@quicinc.com>

With the new SCM calls that interface with TrustZone and allow us to use
the Hardware Key Manager functionality, we can now add support for
hardware wrapped keys to the Qualcomm ICE SoC driver.

Upcoming patches will connect that layer with the block layer ioctls.

Tested-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Gaurav Kashyap <quic_gaurkash@quicinc.com>
Co-developed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/soc/qcom/ice.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++
 include/soc/qcom/ice.h |  8 ++++++
 2 files changed, 86 insertions(+)

diff --git a/drivers/soc/qcom/ice.c b/drivers/soc/qcom/ice.c
index 4ed64845455f..1f6d3566b9e4 100644
--- a/drivers/soc/qcom/ice.c
+++ b/drivers/soc/qcom/ice.c
@@ -22,6 +22,13 @@
 
 #define AES_256_XTS_KEY_SIZE			64
 
+/*
+ * Wrapped key sizes that HWKM expects and manages is different for different
+ * versions of the hardware.
+ */
+#define QCOM_ICE_HWKM_WRAPPED_KEY_SIZE(v)	\
+	((v) == 1 ? 68 : 100)
+
 /* QCOM ICE registers */
 #define QCOM_ICE_REG_VERSION			0x0008
 #define QCOM_ICE_REG_FUSE_SETTING		0x0010
@@ -448,6 +455,77 @@ int qcom_ice_derive_sw_secret(struct qcom_ice *ice, const u8 wkey[],
 }
 EXPORT_SYMBOL_GPL(qcom_ice_derive_sw_secret);
 
+/**
+ * qcom_ice_generate_key() - Generate a wrapped key for inline encryption
+ * @lt_key: long-term wrapped key to be generated, which is
+ *          BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE in size.
+ *
+ * Make a scm call into trustzone to generate a wrapped key for storage
+ * encryption using hwkm.
+ *
+ * Returns: 0 on success, -errno on failure.
+ */
+int qcom_ice_generate_key(struct qcom_ice *ice,
+			  u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+	size_t wk_size = QCOM_ICE_HWKM_WRAPPED_KEY_SIZE(ice->hwkm_version);
+
+	if (!qcom_scm_generate_ice_key(lt_key, wk_size))
+		return wk_size;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(qcom_ice_generate_key);
+
+/**
+ * qcom_ice_prepare_key() - Prepare a long-term wrapped key for inline encryption
+ * @lt_key: longterm wrapped key that was generated or imported.
+ * @lt_key_size: size of the longterm wrapped_key
+ * @eph_key: wrapped key returned which has been wrapped with a per-boot ephemeral key,
+ *           size of which is BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE in size.
+ *
+ * Make a scm call into trustzone to prepare a wrapped key for storage
+ * encryption by rewrapping the longterm wrapped key with a per boot ephemeral
+ * key using hwkm.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_ice_prepare_key(struct qcom_ice *ice, const u8 *lt_key, size_t lt_key_size,
+			 u8 eph_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+	size_t wk_size = QCOM_ICE_HWKM_WRAPPED_KEY_SIZE(ice->hwkm_version);
+
+	if (!qcom_scm_prepare_ice_key(lt_key, lt_key_size, eph_key, wk_size))
+		return wk_size;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(qcom_ice_prepare_key);
+
+/**
+ * qcom_ice_import_key() - Import a raw key for inline encryption
+ * @imp_key: raw key that has to be imported
+ * @imp_key_size: size of the imported key
+ * @lt_key: longterm wrapped key that is imported, which is
+ *          BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE in size.
+ *
+ * Make a scm call into trustzone to import a raw key for storage encryption
+ * and generate a longterm wrapped key using hwkm.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_ice_import_key(struct qcom_ice *ice, const u8 *imp_key, size_t imp_key_size,
+			u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE])
+{
+	size_t wk_size = QCOM_ICE_HWKM_WRAPPED_KEY_SIZE(ice->hwkm_version);
+
+	if (!qcom_scm_import_ice_key(imp_key, imp_key_size, lt_key, wk_size))
+		return wk_size;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(qcom_ice_import_key);
+
 static struct qcom_ice *qcom_ice_create(struct device *dev,
 					void __iomem *base)
 {
diff --git a/include/soc/qcom/ice.h b/include/soc/qcom/ice.h
index dabe0d3a1fd0..dcf277d196ff 100644
--- a/include/soc/qcom/ice.h
+++ b/include/soc/qcom/ice.h
@@ -39,5 +39,13 @@ bool qcom_ice_hwkm_supported(struct qcom_ice *ice);
 int qcom_ice_derive_sw_secret(struct qcom_ice *ice, const u8 wkey[],
 			      unsigned int wkey_size,
 			      u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]);
+int qcom_ice_generate_key(struct qcom_ice *ice,
+			  u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+int qcom_ice_prepare_key(struct qcom_ice *ice,
+			 const u8 *lt_key, size_t lt_key_size,
+			 u8 eph_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+int qcom_ice_import_key(struct qcom_ice *ice,
+			const u8 *imp_key, size_t imp_key_size,
+			u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
 struct qcom_ice *of_qcom_ice_get(struct device *dev);
 #endif /* __QCOM_ICE_H__ */

-- 
2.43.0