[PATCH v4 13/22] efi_loader: enable TEE runtime SetVariable() over FF-A

Add the TEE-backed runtime SetVariable() implementation for the FF-A/MM
variable backend. The runtime path uses EFI runtime-safe memory helpers
and the shared MM communication path so SetVariable() can reach the MM
secure partition after ExitBootServices().

Add runtime-safe variable-property helpers for the SetVariable() path
and use the original data_size argument when restoring the read-only
property maxsize, instead of relying on the MM response buffer.

Reviewed-by: Simon Glass <[email protected]>
Signed-off-by: Harsimran Singh Tungal <[email protected]>
---
 lib/efi_loader/efi_variable_tee.c | 147 ++++++++++++++++++++++++++++--
 1 file changed, 140 insertions(+), 7 deletions(-)

diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
index 5c7104662e9..d04b8dc1376 100644
--- a/lib/efi_loader/efi_variable_tee.c
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -717,6 +717,38 @@ out:
 	return ret;
 }
 
+static efi_status_t __efi_runtime set_property_int_runtime(const u16 *variable_name,
+							   efi_uintn_t name_size,
+							   const efi_guid_t *vendor,
+							   struct var_check_property *var_property)
+{
+	struct smm_variable_var_check_property *smm_property;
+	efi_uintn_t payload_size;
+	u8 *comm_buf = NULL;
+	efi_status_t ret;
+
+	payload_size = sizeof(*smm_property) + name_size;
+	if (payload_size > max_payload_size) {
+		ret = EFI_INVALID_PARAMETER;
+		return ret;
+	}
+	comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
+				SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_SET,
+				&ret);
+	if (!comm_buf)
+		return ret;
+
+	efi_memcpy_runtime(&smm_property->guid, vendor, sizeof(*vendor));
+	smm_property->name_size = name_size;
+	efi_memcpy_runtime(&smm_property->property, var_property,
+			   sizeof(smm_property->property));
+	efi_memcpy_runtime(smm_property->name, variable_name, name_size);
+
+	ret = mm_communicate(comm_buf, payload_size);
+
+	return ret;
+}
+
 static efi_status_t get_property_int(const u16 *variable_name,
 				     efi_uintn_t name_size,
 				     const efi_guid_t *vendor,
@@ -762,6 +794,49 @@ out:
 	return ret;
 }
 
+static efi_status_t __efi_runtime get_property_int_runtime(const u16 *variable_name,
+							   efi_uintn_t name_size,
+							   const efi_guid_t *vendor,
+							   struct var_check_property *var_property)
+{
+	struct smm_variable_var_check_property *smm_property;
+	efi_uintn_t payload_size;
+	u8 *comm_buf = NULL;
+	efi_status_t ret;
+
+	efi_memset_runtime(var_property, 0, sizeof(*var_property));
+	payload_size = sizeof(*smm_property) + name_size;
+	if (payload_size > max_payload_size) {
+		ret = EFI_INVALID_PARAMETER;
+		return ret;
+	}
+	comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
+				SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET,
+				&ret);
+	if (!comm_buf)
+		return ret;
+
+	efi_memcpy_runtime(&smm_property->guid, vendor, sizeof(smm_property->guid));
+	smm_property->name_size = name_size;
+	efi_memcpy_runtime(smm_property->name, variable_name, name_size);
+
+	ret = mm_communicate(comm_buf, payload_size);
+	/*
+	 * Currently only R/O property is supported in StMM.
+	 * Variables that are not set to R/O will not set the property in StMM
+	 * and the call will return EFI_NOT_FOUND. We are setting the
+	 * properties to 0x0 so checking against that is enough for the
+	 * EFI_NOT_FOUND case.
+	 */
+	if (ret == EFI_NOT_FOUND)
+		return EFI_SUCCESS;
+	if (ret != EFI_SUCCESS)
+		return ret;
+	efi_memcpy_runtime(var_property, &smm_property->property, sizeof(*var_property));
+
+	return EFI_SUCCESS;
+}
+
 efi_status_t efi_get_variable_int(const u16 *variable_name,
 				  const efi_guid_t *vendor,
 				  u32 *attributes, efi_uintn_t *data_size,
@@ -995,7 +1070,7 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
 		var_property.property |= VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
 		var_property.attributes = attributes;
 		var_property.minsize = 1;
-		var_property.maxsize = var_acc->data_size;
+		var_property.maxsize = data_size;
 		ret = set_property_int(variable_name, name_size, vendor, &var_property);
 	}
 
@@ -1072,7 +1147,7 @@ efi_query_variable_info_runtime(u32 attributes, u64 *max_variable_storage_size,
 }
 
 /**
- * efi_set_variable_runtime() - runtime implementation of SetVariable()
+ * efi_set_variable_int_runtime() - runtime implementation of SetVariable()
  *
  * @variable_name:	name of the variable
  * @guid:		vendor GUID
@@ -1082,11 +1157,69 @@ efi_query_variable_info_runtime(u32 attributes, u64 *max_variable_storage_size,
  * Return:		status code
  */
 static efi_status_t __efi_runtime EFIAPI
-efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
-			 u32 attributes, efi_uintn_t data_size,
-			 const void *data)
+efi_set_variable_int_runtime(u16 *variable_name, const efi_guid_t *guid,
+			     u32 attributes, efi_uintn_t data_size,
+			     const void *data)
 {
-	return EFI_UNSUPPORTED;
+	efi_status_t ret, mm_communicate_ret = EFI_SUCCESS;
+	struct var_check_property var_property;
+	struct smm_variable_access *var_acc;
+	efi_uintn_t payload_size;
+	efi_uintn_t name_size;
+	u8 *comm_buf = NULL;
+	bool ro;
+
+	if (!variable_name || variable_name[0] == 0 || !guid)
+		return EFI_INVALID_PARAMETER;
+
+	if (data_size > 0 && !data)
+		return EFI_INVALID_PARAMETER;
+
+	/* Check payload size */
+	name_size = u16_strsize(variable_name);
+	payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
+	if (payload_size > max_payload_size)
+		return EFI_INVALID_PARAMETER;
+
+	ro = !!(attributes & EFI_VARIABLE_READ_ONLY);
+	attributes &= EFI_VARIABLE_MASK;
+
+	ret = get_property_int_runtime(variable_name, name_size, guid,
+				       &var_property);
+	if (ret != EFI_SUCCESS)
+		return ret;
+
+	if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)
+		return EFI_WRITE_PROTECTED;
+
+	comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
+				SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
+	if (!comm_buf)
+		return ret;
+
+	/* Fill in contents */
+	efi_memcpy_runtime(&var_acc->guid, guid, sizeof(*guid));
+	var_acc->data_size = data_size;
+	var_acc->name_size = name_size;
+	var_acc->attr = attributes;
+	efi_memcpy_runtime(var_acc->name, variable_name, name_size);
+	efi_memcpy_runtime((u8 *)var_acc->name + name_size, data, data_size);
+
+	/* Communicate */
+	ret = mm_communicate(comm_buf, payload_size);
+	if (ret != EFI_SUCCESS)
+		mm_communicate_ret = ret;
+
+	if (ro && !(var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)) {
+		var_property.revision = VAR_CHECK_VARIABLE_PROPERTY_REVISION;
+		var_property.property |= VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
+		var_property.attributes = attributes;
+		var_property.minsize = 1;
+		var_property.maxsize = data_size;
+		ret = set_property_int_runtime(variable_name, name_size, guid, &var_property);
+	}
+
+	return (mm_communicate_ret == EFI_SUCCESS) ? ret : mm_communicate_ret;
 }
 
 /**
@@ -1123,7 +1256,7 @@ void efi_variables_boot_exit_notify(void)
 	efi_runtime_services.get_variable = efi_get_variable_runtime;
 	efi_runtime_services.get_next_variable_name =
 			efi_get_next_variable_name_runtime;
-	efi_runtime_services.set_variable = efi_set_variable_runtime;
+	efi_runtime_services.set_variable = efi_set_variable_int_runtime;
 	efi_update_table_header_crc32(&efi_runtime_services.hdr);
 
 	/* Record that ExitBootServices() has been called */
-- 
2.34.1