COCOS-153 - Add host-data option

[danko-miladinovic]

What type of PR is this?

This is a feature because it adds:

• QEMU host-data option to the launching of CVMs.

This PR also renames the platform_info.json into backend_info.json.

What does this do?

This PR enables the Manager to launch CVMs with the host-data filed of the attestation report populated with the computation configuration of the Agent. This way, the Agent can check what is being sent to him by the Manager.
This PR also renames the platform_info.json into backend_info.json.

Which issue(s) does this PR fix/relate to?

• Resolves Feature: Add host-data QEMU option to CVM boot up #153

Have you included tests for your changes?

The manual README.md has been changed to reflect this new feature.

Did you document any new/modified feature?

Documentation will be updated in a separate PR.

Notes

[SammyOina]

move to a function

[danko-miladinovic]

Done

[dborovcanin]

RootOfTrust

[danko-miladinovic]

Done, my mistake. Thanks.

[dborovcanin]

Rename to computationHash and use like ch := computationHash(ac). If there is no need to pass the pointer param here (i.e. we do not change the computation from this function), pass by value instead.

[danko-miladinovic]

Done. The computation is passed by value now.

[dborovcanin]

Is it possible to simplify with something like:

Suggested change

	measurement, err := base64.StdEncoding.DecodeString(args[0])
	if err != nil {
	log.Fatalf("Error could not decode base64: %v", err)
	}
	if len(measurement) != measurementLength {
	log.Fatalf("Measurement must be 48 bytes in length")
	}
	attestationConfiguration := AttestationConfiguration{}
	backendInfo, err := os.OpenFile(args[1], os.O_RDWR, filePermision)
	if err != nil {
	log.Fatalf("Error opening the backend information file: %v", err)
	}
	defer backendInfo.Close()
	decoder := json.NewDecoder(backendInfo)
	err = decoder.Decode(&attestationConfiguration)
	if err != nil {
	log.Fatalf("Error decoding the backend information file: %v", err)
	}
	attestationConfiguration.SNPPolicy.Measurement = measurement
	if err = backendInfo.Truncate(0); err != nil {
	log.Fatalf("Error could not truncate backend information JSON file: %v", err)
	}
	fileJson, err := json.MarshalIndent(attestationConfiguration, "", " ")
	if err != nil {
	log.Fatalf("Error marshaling the backend information JSON: %v", err)
	}
	if err = os.WriteFile(backendInfo.Name(), fileJson, filePermision); err != nil {
	log.Fatalf("Error writing into backend information JSON file: %v", err)
	}
	measurement, err := base64.StdEncoding.DecodeString(args[0])
	if err != nil {
	log.Fatalf("Error could not decode base64: %v", err)
	}
	if len(measurement) != measurementLength {
	log.Fatalf("Measurement must be 48 bytes in length")
	}
	ac := AttestationConfiguration{}
	bi, err := os.ReadFile(args[1])
	if err != nil {
	log.Fatalf("Failed to read the config file: %v", err)
	}
	if err := json.Unmarshal(bi, &ac); err != nil {
	log.Fatalf("Failed to unmarshal JSON data: %v", err)
	}
	ac.SNPPolicy.Measurement = measurement
	bi, err = json.MarshalIndent(ac, "", "")
	if err != nil {
	log.Fatalf("Failed to marshal JSON configuration: %v", err)
	}
	if err := os.WriteFile(args[1], bi, filePermission); err != nil {
	log.Fatalf("Failed to write config to the file: %v", err)
	}

[danko-miladinovic]

Done

[dborovcanin]

Fix typo permission. Also, consider completely removing it and using predefined modes from the fs like fs.<Whatever_mode_we_need_here>.

[dborovcanin]

There are a lot of repetitions, please extract to an unexported function.

[danko-miladinovic]

Changed. I have written a single function that alters the backend info file (adds the measurement and host data) and takes the fieldType argument so that the function knows if it should change the measurement field or host data field.

[SammyOina]

Suggested change

	// 0o744 file permission gives RWX permission to the user and only the R permission to others
	// 0o744 file permission gives RWX permission to the user and only the R permission to others.

[dborovcanin]

Add a default case that returns an error.

[danko-miladinovic]

Done