}

	if token == "" && cred.IsTemp() && !cred.IsServiceAccount() {
		// Temporary credentials should always have x-amz-security-token
		return nil, ErrInvalidToken
	}

	if token != "" && !cred.IsTemp() {
		// x-amz-security-token should not present for static credentials.
		return nil, ErrInvalidToken
	}

	// account or STS account):
	requestorUser := cred.AccessKey
	requestorParentUser := cred.AccessKey
	requestorGroups := cred.Groups
	requestorIsDerivedCredential := false
	if cred.IsServiceAccount() || cred.IsTemp() {
		requestorParentUser = cred.ParentUser
		requestorIsDerivedCredential = true
	}

	// Check if we are creating svc account for request sender.

	if s3Err != ErrNone {
		return auth.Credentials{}, s3Err
	}

	// Temporary credentials or Service accounts cannot generate further temporary credentials.
	if user.IsTemp() || user.IsServiceAccount() {
		return auth.Credentials{}, ErrAccessDenied
	}

	// Session tokens are not allowed in STS AssumeRole requests.
	if getSessionToken(r) != "" {
		return auth.Credentials{}, ErrAccessDenied
	}