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sec-design.md

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Okay, let's create a design document for the gRPC-Go project.

BUSINESS POSTURE

gRPC-Go is Google's implementation of the gRPC framework in Go. gRPC is a high-performance, open-source universal RPC framework, that puts mobile and HTTP/2 first. gRPC is designed for building scalable and low-latency distributed systems. It's used for connecting services in and across data centers, and it also supports pluggable load balancing, tracing, health checking, and authentication.

Priorities:

  • Provide a robust, efficient, and reliable RPC framework for Go developers.
  • Maintain compatibility with the gRPC specification and other language implementations.
  • Support a wide range of use cases, from microservices to mobile applications.
  • Ensure high performance and low latency.
  • Provide a secure and extensible platform.

Goals:

  • Enable developers to easily build distributed systems using Go.
  • Facilitate communication between services, regardless of their underlying infrastructure.
  • Promote interoperability between different programming languages and platforms.

Business Risks:

  • Incompatibility with other gRPC implementations could lead to fragmentation and limit adoption.
  • Performance bottlenecks could hinder the use of gRPC-Go in high-throughput scenarios.
  • Security vulnerabilities could expose user data and compromise system integrity.
  • Lack of features or poor usability could drive developers to alternative solutions.
  • Failure to keep up with evolving standards and technologies could lead to obsolescence.

SECURITY POSTURE

Existing Security Controls:

  • security control: TLS support for secure communication. Implemented in the transport layer.
  • security control: Authentication mechanisms (e.g., OAuth2, JWT). Described in the authentication documentation and examples.
  • security control: Interceptors for implementing custom security logic (e.g., authorization). Described in the interceptor documentation.
  • security control: Regular security audits and vulnerability scanning. Part of the gRPC project's development process.
  • security control: Fuzz testing. Part of continuous integration.
  • security control: Support for ALTS (Application Layer Transport Security). Described in ALTS documentation.

Accepted Risks:

  • accepted risk: The framework relies on the underlying operating system and network infrastructure for some security guarantees.
  • accepted risk: Users are responsible for securely managing their credentials and keys.
  • accepted risk: Users are responsible for implementing appropriate authorization logic for their applications.
  • accepted risk: Complex configuration may lead to misconfigurations and security vulnerabilities if not carefully managed.

Recommended Security Controls:

  • security control: Implement comprehensive input validation to prevent injection attacks.
  • security control: Provide clear guidance and examples for securely configuring and deploying gRPC-Go applications.
  • security control: Integrate with security linters and static analysis tools to identify potential vulnerabilities during development.
  • security control: Consider adding support for additional authentication and authorization mechanisms.

Security Requirements:

  • Authentication:

    • Support for mutual TLS authentication.
    • Integration with common identity providers (e.g., Google, AWS, Azure).
    • Support for token-based authentication (e.g., JWT, OAuth2).
    • Mechanisms for securely managing and rotating credentials.

  • Authorization:

    • Support for role-based access control (RBAC).
    • Ability to define fine-grained access control policies.
    • Integration with external authorization services.

  • Input Validation:

    • Strict validation of all incoming data based on Protobuf definitions.
    • Protection against common injection attacks (e.g., SQL injection, command injection).
    • Sanitization of user-provided input.

  • Cryptography:

    • Use of strong, well-vetted cryptographic algorithms.
    • Secure key management practices.
    • Protection against replay attacks.
    • Support for data encryption at rest and in transit.

DESIGN

C4 CONTEXT

graph LR
    subgraph "gRPC-Go System Context"
        ClientApp["Client Application"] -- "Uses" --> GRPCGo["gRPC-Go Framework"]
        GRPCGo -- "Communicates with (gRPC)" --> RemoteService["Remote gRPC Service"]
        Developer["Developer"] -- "Develops with" --> GRPCGo
        GRPCGo -- "Uses" --> GoStandardLibrary["Go Standard Library"]
    end
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Element Descriptions:

  • Client Application:

    • Name: Client Application
    • Type: External System
    • Description: An application that uses the gRPC-Go framework to communicate with a remote service.
    • Responsibilities: Initiates gRPC calls, handles responses, manages application-specific logic.
    • Security controls: Implements authentication and authorization logic, validates input, handles sensitive data securely.

  • gRPC-Go Framework:

    • Name: gRPC-Go Framework
    • Type: System
    • Description: The core gRPC-Go library providing functionalities for building gRPC clients and servers.
    • Responsibilities: Handles serialization/deserialization, transport, connection management, and provides APIs for defining and implementing services.
    • Security controls: TLS support, authentication mechanisms, interceptors for custom security logic.

  • Remote gRPC Service:

    • Name: Remote gRPC Service
    • Type: External System
    • Description: A service that implements a gRPC interface and can be accessed by gRPC-Go clients.
    • Responsibilities: Processes incoming requests, performs business logic, returns responses.
    • Security controls: Implements authentication and authorization logic, validates input, handles sensitive data securely.

  • Developer:

    • Name: Developer
    • Type: User
    • Description: A software developer who uses the gRPC-Go framework to build applications.
    • Responsibilities: Writes code, defines service interfaces, configures the framework, implements security measures.
    • Security controls: Follows secure coding practices, uses secure development tools, manages credentials securely.

  • Go Standard Library:

    • Name: Go Standard Library
    • Type: External Dependency
    • Description: The standard library of the Go programming language.
    • Responsibilities: Provides core functionalities like networking, I/O, and cryptography.
    • Security controls: Relies on the security of the Go runtime and underlying operating system.

C4 CONTAINER

graph LR
    subgraph "gRPC-Go Containers"
        ClientApp["Client Application"] -- "gRPC Calls" --> ClientAPI["Client API"]
        ClientAPI -- "Uses" --> Transport["Transport Layer"]
        Transport -- "HTTP/2" --> TransportServer["Transport Layer (Server)"]
        TransportServer -- "Uses" --> ServerAPI["Server API"]
        ServerAPI -- "Handles Requests" --> ServiceImpl["Service Implementation"]
        ServiceImpl -- "Returns Responses" --> ServerAPI
        ClientAPI -- "Uses" --> Codec["Codec (Serialization/Deserialization)"]
        ServerAPI -- "Uses" --> Codec
        ClientAPI -- "Uses" --> InterceptorsClient["Interceptors (Client)"]
        ServerAPI -- "Uses" --> InterceptorsServer["Interceptors (Server)"]
    end
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Element Descriptions:

  • Client Application:

    • Name: Client Application
    • Type: External System
    • Description: An application that uses the gRPC-Go framework.
    • Responsibilities: Initiates gRPC calls, handles responses.
    • Security controls: Application-level security, authentication, input validation.

  • Client API:

    • Name: Client API
    • Type: Container
    • Description: The API used by client applications to interact with gRPC-Go.
    • Responsibilities: Provides functions for creating clients, making RPC calls, and managing connections.
    • Security controls: Handles authentication credentials, enforces TLS configuration.

  • Transport Layer (Client):

    • Name: Transport Layer
    • Type: Container
    • Description: Handles the underlying communication using HTTP/2.
    • Responsibilities: Manages connections, sends and receives data, implements flow control.
    • Security controls: TLS implementation, certificate validation.

  • Transport Layer (Server):

    • Name: Transport Layer (Server)
    • Type: Container
    • Description: Handles the underlying communication using HTTP/2.
    • Responsibilities: Manages connections, sends and receives data, implements flow control.
    • Security controls: TLS implementation, certificate validation.

  • Server API:

    • Name: Server API
    • Type: Container
    • Description: The API used by server applications to implement gRPC services.
    • Responsibilities: Provides functions for registering services, handling requests, and sending responses.
    • Security controls: Handles authentication credentials, enforces TLS configuration.

  • Service Implementation:

    • Name: Service Implementation
    • Type: Container
    • Description: The user-provided code that implements the business logic of the gRPC service.
    • Responsibilities: Processes requests, performs actions, generates responses.
    • Security controls: Application-specific authorization, input validation, data sanitization.

  • Codec (Serialization/Deserialization):

    • Name: Codec
    • Type: Container
    • Description: Handles the serialization and deserialization of messages using Protobuf.
    • Responsibilities: Converts data between Protobuf messages and byte streams.
    • Security controls: Input validation based on Protobuf schema.

  • Interceptors (Client):

    • Name: Interceptors (Client)
    • Type: Container
    • Description: Allows for intercepting and modifying gRPC calls on the client-side.
    • Responsibilities: Can be used for logging, authentication, authorization, tracing, etc.
    • Security controls: Can implement custom authentication and authorization logic.

  • Interceptors (Server):

    • Name: Interceptors (Server)
    • Type: Container
    • Description: Allows for intercepting and modifying gRPC calls on the server-side.
    • Responsibilities: Can be used for logging, authentication, authorization, tracing, etc.
    • Security controls: Can implement custom authentication and authorization logic.

DEPLOYMENT

Possible Deployment Solutions:

  1. Standalone binaries running directly on virtual machines or bare-metal servers.
  2. Containers (e.g., Docker) running on a container orchestration platform (e.g., Kubernetes, Nomad).
  3. Serverless functions (e.g., AWS Lambda, Google Cloud Functions) triggered by gRPC requests (requires a gateway or proxy).

Chosen Solution: Container Orchestration with Kubernetes

graph LR
    subgraph "Kubernetes Cluster"
        subgraph "Namespace"
            Pod["Pod (gRPC-Go Service)"] -- "HTTP/2" --> Service["Kubernetes Service"]
            Pod -- "Uses" --> Container["Container (gRPC-Go Application)"]
        end
        Ingress["Ingress Controller"] -- "External Traffic" --> Service
    end
    Client["External Client"] -- "gRPC" --> Ingress
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Element Descriptions:

  • External Client:

    • Name: External Client
    • Type: External System
    • Description: A client application running outside the Kubernetes cluster.
    • Responsibilities: Initiates gRPC calls to the service.
    • Security controls: Client-side security measures, potentially including TLS.

  • Ingress Controller:

    • Name: Ingress Controller
    • Type: Infrastructure Node
    • Description: A component that manages external access to services in the cluster.
    • Responsibilities: Routes incoming traffic to the appropriate Kubernetes Service.
    • Security controls: TLS termination, potentially WAF (Web Application Firewall).

  • Kubernetes Service:

    • Name: Kubernetes Service
    • Type: Logical Node
    • Description: An abstraction that defines a logical set of Pods and a policy by which to access them.
    • Responsibilities: Provides a stable endpoint for accessing the gRPC-Go service.
    • Security controls: Network policies can restrict access to the service.

  • Pod (gRPC-Go Service):

    • Name: Pod (gRPC-Go Service)
    • Type: Logical Node
    • Description: A Kubernetes Pod running one or more containers.
    • Responsibilities: Hosts the gRPC-Go application container.
    • Security controls: Limited resources, potentially restricted network access.

  • Container (gRPC-Go Application):

    • Name: Container (gRPC-Go Application)
    • Type: Container
    • Description: A Docker container running the compiled gRPC-Go application.
    • Responsibilities: Executes the gRPC-Go service code.
    • Security controls: Runs as a non-root user, minimal privileges, image vulnerability scanning.

  • Namespace

    • Name: Namespace
    • Type: Logical Node
    • Description: Provides a scope for names. Use of multiple namespaces is optional.
    • Responsibilities: Namespaces are a way to divide cluster resources between multiple users.
    • Security controls: Resource quotas, network policies.

BUILD

graph LR
    Developer["Developer"] -- "Commits Code" --> GitRepository["Git Repository (GitHub)"]
    GitRepository -- "Triggers" --> CIWorkflow["CI Workflow (GitHub Actions)"]
    CIWorkflow -- "Runs Tests" --> Tests["Unit & Integration Tests"]
    CIWorkflow -- "Builds" --> Build["Build Process (go build)"]
    Build -- "Generates" --> Binary["Go Binary"]
    CIWorkflow -- "Scans" --> SecurityChecks["Security Checks (SAST, SCA)"]
    SecurityChecks -- "Reports" --> CIWorkflow
    CIWorkflow -- "Packages" --> DockerBuild["Docker Build"]
    DockerBuild -- "Creates" --> DockerImage["Docker Image"]
    DockerImage -- "Pushes to" --> ContainerRegistry["Container Registry"]
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Build Process Description:

  1. Developer commits code to the Git repository (GitHub).
  2. The commit triggers a CI workflow (GitHub Actions).
  3. The CI workflow runs unit and integration tests.
  4. The CI workflow executes the build process using go build, generating a Go binary.
  5. Security checks (SAST - Static Application Security Testing, SCA - Software Composition Analysis) are performed on the code and its dependencies. Tools like gosec, snyk, or GitHub's built-in dependency scanning could be used.
  6. The CI workflow builds a Docker image using a Dockerfile. The Dockerfile should follow best practices for security, such as using a minimal base image, running as a non-root user, and avoiding unnecessary dependencies.
  7. The Docker image is pushed to a container registry (e.g., Docker Hub, Google Container Registry, AWS ECR).

Security Controls in Build Process:

  • security control: Code review: All code changes are reviewed by at least one other developer before being merged.
  • security control: Automated testing: Unit and integration tests are run automatically on every commit.
  • security control: SAST: Static analysis tools are used to identify potential security vulnerabilities in the code.
  • security control: SCA: Software composition analysis tools are used to identify known vulnerabilities in third-party dependencies.
  • security control: Docker image scanning: The Docker image is scanned for vulnerabilities before being pushed to the container registry.
  • security control: Signed commits: Developers sign their commits to ensure authenticity.
  • security control: Least privilege: Build processes run with minimal necessary privileges.

RISK ASSESSMENT

Critical Business Processes:

  • Reliable and efficient inter-service communication: gRPC-Go is fundamental for communication between services in distributed systems. Any disruption or performance degradation directly impacts the functionality of applications relying on it.
  • Data integrity and confidentiality: gRPC-Go handles potentially sensitive data. Ensuring its integrity and confidentiality during transmission is crucial.

Data Sensitivity:

  • The sensitivity of the data handled by gRPC-Go depends entirely on the specific applications using it. It can range from non-sensitive metadata to highly confidential information like PII (Personally Identifiable Information), financial data, or healthcare records. Therefore, the design and implementation of applications using gRPC-Go must consider the sensitivity of the data being transmitted and implement appropriate security controls.

QUESTIONS & ASSUMPTIONS

Questions:

  • What specific compliance requirements (e.g., PCI DSS, HIPAA, GDPR) must applications built with gRPC-Go adhere to? This will influence the necessary security controls.
  • What are the expected performance requirements (throughput, latency) for typical use cases?
  • What are the existing security policies and procedures of organizations that will be using gRPC-Go?
  • What level of access do developers have to production environments?
  • What are the specific threat models for the applications that will be using gRPC-Go?

Assumptions:

  • BUSINESS POSTURE: It is assumed that maintaining compatibility with other gRPC implementations is a high priority.
  • BUSINESS POSTURE: It is assumed that performance is a critical factor for most users.
  • SECURITY POSTURE: It is assumed that users will be responsible for implementing appropriate authorization logic within their applications.
  • SECURITY POSTURE: It is assumed that users will be responsible for securely managing their credentials and keys.
  • DESIGN: It is assumed that Kubernetes will be a common deployment platform for gRPC-Go services.
  • DESIGN: It is assumed that GitHub Actions will be a common CI/CD platform.
  • DESIGN: It is assumed that developers are familiar with Go, Protobuf, and gRPC concepts.