[PATCH v7 07/17] firmware: qcom: scm: add calls for creating, preparing and importing keys

[Bartosz Golaszewski]

From: Gaurav Kashyap <quic_gaurkash@xxxxxxxxxxx>

Storage encryption has two IOCTLs for creating, importing and preparing
keys for encryption. For wrapped keys, these IOCTLs need to interface
with Qualcomm's Trustzone. Add the following keys:

generate_key:
  This is used to generate and return a longterm wrapped key. Trustzone
  achieves this by generating a key and then wrapping it using the
  Hawrdware Key Manager (HWKM), returning a wrapped keyblob.

import_key:
  The functionality is similar to generate, but here: a raw key is
  imported into the HWKM and a longterm wrapped keyblob is returned.

prepare_key:
  The longterm wrapped key from the import or generate calls is made
  further secure by rewrapping it with a per-boot, ephemeral wrapped key
  before installing it in the kernel for programming into ICE.

Tested-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Signed-off-by: Gaurav Kashyap <quic_gaurkash@xxxxxxxxxxx>
[Bartosz:
  improve kerneldocs,
  fix hex values coding style,
  rewrite commit message]
Co-developed-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
 drivers/firmware/qcom/qcom_scm.c       | 161 +++++++++++++++++++++++++++++++++
 drivers/firmware/qcom/qcom_scm.h       |   3 +
 include/linux/firmware/qcom/qcom_scm.h |   5 +
 3 files changed, 169 insertions(+)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index de90d21c2dfa..3a59fd2a45b5 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -1317,6 +1317,167 @@ int qcom_scm_derive_sw_secret(const u8 *wkey, size_t wkey_size,
 }
 EXPORT_SYMBOL_GPL(qcom_scm_derive_sw_secret);
 
+/**
+ * qcom_scm_generate_ice_key() - Generate a wrapped key for encryption.
+ * @lt_key: the wrapped key returned after key generation
+ * @lt_key_size: size of the wrapped key to be returned.
+ *
+ * Generate a key using the built-in HW module in the SoC. Wrap the key using
+ * the platform-specific Key Encryption Key and return to the caller.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_generate_ice_key(u8 *lt_key, size_t lt_key_size)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_ES,
+		.cmd =  QCOM_SCM_ES_GENERATE_ICE_KEY,
+		.arginfo = QCOM_SCM_ARGS(2, QCOM_SCM_RW, QCOM_SCM_VAL),
+		.args[1] = lt_key_size,
+		.owner = ARM_SMCCC_OWNER_SIP,
+	};
+
+	int ret;
+
+	void *lt_key_buf __free(qcom_tzmem) = qcom_tzmem_alloc(__scm->mempool,
+							       lt_key_size,
+							       GFP_KERNEL);
+	if (!lt_key_buf)
+		return -ENOMEM;
+
+	desc.args[0] = qcom_tzmem_to_phys(lt_key_buf);
+
+	ret = qcom_scm_call(__scm->dev, &desc, NULL);
+	if (!ret)
+		memcpy(lt_key, lt_key_buf, lt_key_size);
+
+	memzero_explicit(lt_key_buf, lt_key_size);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_scm_generate_ice_key);
+
+/**
+ * qcom_scm_prepare_ice_key() - Get the per-boot ephemeral wrapped key
+ * @lt_key: the longterm wrapped key
+ * @lt_key_size: size of the wrapped key
+ * @eph_key: ephemeral wrapped key to be returned
+ * @eph_key_size: size of the ephemeral wrapped key
+ *
+ * Qualcomm wrapped keys (longterm keys) are rewrapped with a per-boot
+ * ephemeral key for added protection. These are ephemeral in nature as
+ * they are valid only for that boot.
+ *
+ * Retrieve the key wrapped with the per-boot ephemeral key and return it to
+ * the caller.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_prepare_ice_key(const u8 *lt_key, size_t lt_key_size,
+			     u8 *eph_key, size_t eph_key_size)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_ES,
+		.cmd =  QCOM_SCM_ES_PREPARE_ICE_KEY,
+		.arginfo = QCOM_SCM_ARGS(4, QCOM_SCM_RO,
+					 QCOM_SCM_VAL, QCOM_SCM_RW,
+					 QCOM_SCM_VAL),
+		.args[1] = lt_key_size,
+		.args[3] = eph_key_size,
+		.owner = ARM_SMCCC_OWNER_SIP,
+	};
+
+	int ret;
+
+	void *lt_key_buf __free(qcom_tzmem) = qcom_tzmem_alloc(__scm->mempool,
+							       lt_key_size,
+							       GFP_KERNEL);
+	if (!lt_key_buf)
+		return -ENOMEM;
+
+	void *eph_key_buf __free(qcom_tzmem) = qcom_tzmem_alloc(__scm->mempool,
+								eph_key_size,
+								GFP_KERNEL);
+	if (!eph_key_buf) {
+		ret = -ENOMEM;
+		goto out_free_longterm;
+	}
+
+	memcpy(lt_key_buf, lt_key, lt_key_size);
+	desc.args[0] = qcom_tzmem_to_phys(lt_key_buf);
+	desc.args[2] = qcom_tzmem_to_phys(eph_key_buf);
+
+	ret = qcom_scm_call(__scm->dev, &desc, NULL);
+	if (!ret)
+		memcpy(eph_key, eph_key_buf, eph_key_size);
+
+	memzero_explicit(eph_key_buf, eph_key_size);
+
+out_free_longterm:
+	memzero_explicit(lt_key_buf, lt_key_size);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_scm_prepare_ice_key);
+
+/**
+ * qcom_scm_import_ice_key() - Import a wrapped key for encryption
+ * @imp_key: the raw key that is imported
+ * @imp_key_size: size of the key to be imported
+ * @lt_key: the wrapped key to be returned
+ * @lt_key_size: size of the wrapped key
+ *
+ * Import a raw key and return a long-term wrapped key to the caller.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_import_ice_key(const u8 *imp_key, size_t imp_key_size,
+			    u8 *lt_key, size_t lt_key_size)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_ES,
+		.cmd =  QCOM_SCM_ES_IMPORT_ICE_KEY,
+		.arginfo = QCOM_SCM_ARGS(4, QCOM_SCM_RO,
+					 QCOM_SCM_VAL, QCOM_SCM_RW,
+					 QCOM_SCM_VAL),
+		.args[1] = imp_key_size,
+		.args[3] = lt_key_size,
+		.owner = ARM_SMCCC_OWNER_SIP,
+	};
+
+	int ret;
+
+	void *imp_key_buf __free(qcom_tzmem) = qcom_tzmem_alloc(__scm->mempool,
+								imp_key_size,
+								GFP_KERNEL);
+	if (!imp_key_buf)
+		return -ENOMEM;
+
+	void *lt_key_buf __free(qcom_tzmem) = qcom_tzmem_alloc(__scm->mempool,
+							       lt_key_size,
+							       GFP_KERNEL);
+	if (!lt_key_buf) {
+		ret = -ENOMEM;
+		goto out_free_longterm;
+	}
+
+	memcpy(imp_key_buf, imp_key, imp_key_size);
+	desc.args[0] = qcom_tzmem_to_phys(imp_key_buf);
+	desc.args[2] = qcom_tzmem_to_phys(lt_key_buf);
+
+	ret = qcom_scm_call(__scm->dev, &desc, NULL);
+	if (!ret)
+		memcpy(lt_key, lt_key_buf, lt_key_size);
+
+	memzero_explicit(lt_key_buf, lt_key_size);
+
+out_free_longterm:
+	memzero_explicit(imp_key_buf, imp_key_size);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_scm_import_ice_key);
+
 /**
  * qcom_scm_hdcp_available() - Check if secure environment supports HDCP.
  *
diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
index 5a98b90ece32..85f46ae7bd37 100644
--- a/drivers/firmware/qcom/qcom_scm.h
+++ b/drivers/firmware/qcom/qcom_scm.h
@@ -128,6 +128,9 @@ struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void);
 #define QCOM_SCM_ES_INVALIDATE_ICE_KEY	0x03
 #define QCOM_SCM_ES_CONFIG_SET_ICE_KEY	0x04
 #define QCOM_SCM_ES_DERIVE_SW_SECRET	0x07
+#define QCOM_SCM_ES_GENERATE_ICE_KEY	0x08
+#define QCOM_SCM_ES_PREPARE_ICE_KEY	0x09
+#define QCOM_SCM_ES_IMPORT_ICE_KEY	0x0a
 
 #define QCOM_SCM_SVC_HDCP		0x11
 #define QCOM_SCM_HDCP_INVOKE		0x01
diff --git a/include/linux/firmware/qcom/qcom_scm.h b/include/linux/firmware/qcom/qcom_scm.h
index 0ef4415e2023..b5ab39b35490 100644
--- a/include/linux/firmware/qcom/qcom_scm.h
+++ b/include/linux/firmware/qcom/qcom_scm.h
@@ -105,6 +105,11 @@ int qcom_scm_ice_set_key(u32 index, const u8 *key, u32 key_size,
 			 enum qcom_scm_ice_cipher cipher, u32 data_unit_size);
 int qcom_scm_derive_sw_secret(const u8 *wkey, size_t wkey_size,
 			      u8 *sw_secret, size_t sw_secret_size);
+int qcom_scm_generate_ice_key(u8 *lt_key, size_t lt_key_size);
+int qcom_scm_prepare_ice_key(const u8 *lt_key, size_t lt_key_size,
+			     u8 *eph_key, size_t eph_size);
+int qcom_scm_import_ice_key(const u8 *imp_key, size_t imp_size,
+			    u8 *lt_key, size_t lt_key_size);
 
 bool qcom_scm_hdcp_available(void);
 int qcom_scm_hdcp_req(struct qcom_scm_hdcp_req *req, u32 req_cnt, u32 *resp);

-- 
2.43.0