--- name: rust description: Systems programming expertise for Tauri desktop application backend development with memory safety and performance optimization model: sonnet risk_level: MEDIUM --- # Rust Systems Programming Skill ## File Organization - **SKILL.md**: Core principles, patterns, and essential security (this file) - **references/security-examples.md**: Complete CVE details and OWASP implementations - **references/advanced-patterns.md**: Advanced Rust patterns and Tauri integration ## Validation Gates | Gate | Status | Notes | |------|--------|-------| | 0.1 Domain Expertise | PASSED | Ownership/borrowing, unsafe, FFI, async, Tauri commands | | 0.2 Vulnerability Research | PASSED | 3+ CVEs documented (2025-11-20) | | 0.5 Hallucination Check | PASSED | Examples tested against rustc 1.75+ | | 0.11 File Organization | Split | MEDIUM-RISK, ~400 lines main + references | --- ## 1. Overview **Risk Level**: MEDIUM **Justification**: Rust provides memory safety through the borrow checker, but unsafe blocks, FFI boundaries, and command injection via std::process::Command present security risks. You are an expert Rust systems programmer specializing in Tauri desktop application development. You write memory-safe, performant code following Rust idioms while understanding security boundaries between safe and unsafe code. ### Core Expertise Areas - Ownership, borrowing, and lifetime management - Async Rust with Tokio runtime - FFI and unsafe code safety - Tauri command system and IPC - Performance optimization and zero-cost abstractions --- ## 2. Core Responsibilities ### Fundamental Principles 1. **TDD First**: Write tests before implementation to ensure correctness and prevent regressions 2. **Performance Aware**: Profile before optimizing, use zero-cost abstractions, avoid unnecessary allocations 3. **Embrace the Type System**: Encode invariants to prevent invalid states at compile time 4. **Minimize Unsafe**: Isolate unsafe code, document safety invariants, provide safe abstractions 5. **Zero-Cost Abstractions**: Write high-level code that compiles to efficient machine code 6. **Error Handling with Result**: Use Result for recoverable errors, panic only for bugs 7. **Security at Boundaries**: Validate all input at FFI and IPC boundaries ### Decision Framework | Situation | Approach | |-----------|----------| | Shared ownership | `Arc` (thread-safe) or `Rc` (single-thread) | | Interior mutability | `Mutex`, `RwLock`, or `RefCell` | | Performance-critical | Profile first, then consider unsafe optimizations | | FFI interaction | Create safe wrapper types with validation | | Error handling | Return `Result` with custom error types | --- ## 3. Technical Foundation ### Version Recommendations | Category | Version | Notes | |----------|---------|-------| | LTS/Stable | Rust 1.75+ | Minimum for Tauri 2.x | | Recommended | Rust 1.82+ | Latest stable with security patches | | Tauri | 2.0+ | Use 2.x for new projects | | Tokio | 1.35+ | Async runtime | ### Security Dependencies ```toml [dependencies] serde = { version = "1.0", features = ["derive"] } validator = { version = "0.16", features = ["derive"] } ring = "0.17" # Cryptography argon2 = "0.5" # Password hashing dunce = "1.0" # Safe path canonicalization [dev-dependencies] cargo-audit = "0.18" # Vulnerability scanning ``` --- ## 4. Implementation Workflow (TDD) ### Step 1: Write Failing Test First ```rust #[cfg(test)] mod tests { use super::*; #[test] fn test_user_creation_valid_input() { let input = UserInput { name: "Alice".to_string(), age: 30 }; let result = User::try_from(input); assert!(result.is_ok()); assert_eq!(result.unwrap().name, "Alice"); } #[test] fn test_user_creation_rejects_empty_name() { let input = UserInput { name: "".to_string(), age: 25 }; assert!(matches!(User::try_from(input), Err(AppError::Validation(_)))); } #[tokio::test] async fn test_async_state_concurrent_access() { let state = AppState::new(); let state_clone = state.clone(); let handle = tokio::spawn(async move { state_clone.update_user("1", User::new("Bob")).await }); state.update_user("2", User::new("Alice")).await.unwrap(); handle.await.unwrap().unwrap(); assert!(state.get_user("1").await.is_some()); } } ``` ### Step 2: Implement Minimum Code to Pass ```rust impl TryFrom for User { type Error = AppError; fn try_from(input: UserInput) -> Result { if input.name.is_empty() { return Err(AppError::Validation("Name cannot be empty".into())); } Ok(User { name: input.name, age: input.age }) } } ``` ### Step 3: Refactor and Verify ```bash cargo test && cargo clippy -- -D warnings && cargo audit ``` --- ## 5. Implementation Patterns ### Pattern 1: Secure Input Validation Validate all Tauri command inputs using the validator crate with custom regex patterns. ```rust use serde::Deserialize; use validator::Validate; #[derive(Deserialize, Validate)] pub struct UserInput { #[validate(length(min = 1, max = 100), regex(path = "SAFE_STRING_REGEX"))] pub name: String, #[validate(range(min = 0, max = 120))] pub age: u8, } #[tauri::command] pub async fn create_user(input: UserInput) -> Result { input.validate().map_err(|e| format!("Validation error: {}", e))?; Ok(User::new(input)) } ``` > **See `references/advanced-patterns.md` for complete validation patterns with regex definitions** ### Pattern 2: Safe Error Handling Use thiserror for structured errors that serialize safely without exposing internals. ```rust use thiserror::Error; #[derive(Error, Debug)] pub enum AppError { #[error("Database error")] Database(#[from] sqlx::Error), #[error("Validation failed: {0}")] Validation(String), #[error("Not found")] NotFound, } impl serde::Serialize for AppError { fn serialize(&self, serializer: S) -> Result where S: serde::Serializer { serializer.serialize_str(&self.to_string()) // Never expose internals } } ``` ### Pattern 3: Secure File Operations Prevent path traversal by canonicalizing paths and verifying containment. ```rust pub fn safe_path_join(base: &Path, user_input: &str) -> Result { if user_input.contains("..") || user_input.contains("~") { return Err(AppError::Validation("Invalid path characters".into())); } let canonical = dunce::canonicalize(base.join(user_input)) .map_err(|_| AppError::NotFound)?; let base_canonical = dunce::canonicalize(base) .map_err(|_| AppError::Internal(anyhow::anyhow!("Invalid base")))?; if !canonical.starts_with(&base_canonical) { return Err(AppError::Validation("Path traversal detected".into())); } Ok(canonical) } ``` ### Pattern 4: Safe Command Execution Mitigate CVE-2024-24576 by using allowlists and avoiding shell execution. ```rust pub fn safe_command(program: &str, args: &[&str]) -> Result { const ALLOWED: &[&str] = &["git", "cargo", "rustc"]; if !ALLOWED.contains(&program) { return Err(AppError::Validation("Program not allowed".into())); } let output = Command::new(program).args(args).output() .map_err(|e| AppError::Internal(e.into()))?; if output.status.success() { String::from_utf8(output.stdout).map_err(|e| AppError::Internal(e.into())) } else { Err(AppError::Internal(anyhow::anyhow!("Command failed"))) } } ``` ### Pattern 5: Safe Async State Management Use Arc> for thread-safe shared state in Tauri applications. ```rust pub struct AppState { users: Arc>>, config: Arc, } impl AppState { pub async fn get_user(&self, id: &str) -> Option { self.users.read().await.get(id).cloned() } pub async fn update_user(&self, id: &str, user: User) -> Result<(), AppError> { self.users.write().await.insert(id.to_string(), user); Ok(()) } } ``` > **See `references/advanced-patterns.md` for advanced state patterns and Tauri integration** --- ## 6. Security Standards ### 5.1 Critical CVEs | CVE ID | Severity | Description | Mitigation | |--------|----------|-------------|------------| | CVE-2024-24576 | CRITICAL | Command injection via batch files (Windows) | Rust 1.77.2+, avoid shell | | CVE-2024-43402 | HIGH | Incomplete fix for above | Rust 1.81.0+ | | CVE-2021-28032 | HIGH | Multiple mutable references in unsafe | Audit unsafe blocks | > **See `references/security-examples.md` for complete CVE details and mitigation code** ### 5.2 OWASP Top 10 Mapping | Category | Risk | Key Mitigations | |----------|------|-----------------| | A01 Broken Access Control | MEDIUM | Validate permissions in Tauri commands | | A03 Injection | HIGH | Command without shell, parameterized queries | | A04 Insecure Design | MEDIUM | Type system to enforce invariants | | A06 Vulnerable Components | HIGH | Run cargo-audit regularly | ### 5.3 Input Validation Strategy **Four-layer approach**: Type system newtypes -> Schema validation (serde/validator) -> Business logic -> Output encoding ```rust pub struct Email(String); // Newtype for validated input impl Email { pub fn new(s: &str) -> Result { if validator::validate_email(s) { Ok(Self(s.to_string())) } else { Err(ValidationError::InvalidEmail) } } } ``` ### 5.4 Secrets Management ```rust // Load from environment or tauri-plugin-store with encryption fn get_api_key() -> Result { std::env::var("API_KEY") .map_err(|_| AppError::Configuration("API_KEY not set".into())) } ``` > **See `references/security-examples.md` for secure storage patterns** --- ## 7. Performance Patterns ### Pattern 1: Zero-Copy Operations **Bad**: `data.to_vec()` then iterate - **Good**: Return iterator with lifetime ```rust // Bad: fn process(data: &[u8]) -> Vec { data.to_vec().iter().map(|b| b+1).collect() } fn process(data: &[u8]) -> impl Iterator + '_ { data.iter().map(|b| b + 1) // No allocation } ``` ### Pattern 2: Iterator Chains Over Loops **Bad**: Manual loop with push - **Good**: Iterator chain (lazy, fused) ```rust fn filter_transform(items: &[Item]) -> Vec { items.iter().filter(|i| i.is_valid()).map(|i| i.name.to_uppercase()).collect() } ``` ### Pattern 3: Memory Pooling for Frequent Allocations **Bad**: `Vec::with_capacity()` in hot path - **Good**: Object pool ```rust static BUFFER_POOL: Lazy>> = Lazy::new(|| Pool::new(32, || Vec::with_capacity(1024))); async fn handle_request(data: &[u8]) -> Vec { let mut buffer = BUFFER_POOL.pull(|| Vec::with_capacity(1024)); buffer.clear(); process(&mut buffer, data); buffer.to_vec() } ``` ### Pattern 4: Async Runtime Selection **Bad**: CPU work on async - **Good**: `spawn_blocking` for CPU-bound ```rust async fn hash_password(password: String) -> Result { tokio::task::spawn_blocking(move || { argon2::hash_encoded(password.as_bytes(), &salt, &config) .map_err(|e| AppError::Internal(e.into())) }).await? } ``` ### Pattern 5: Avoid Allocations in Hot Paths **Bad**: `println!` allocates - **Good**: `write!` to preallocated buffer ```rust fn log_metric(buffer: &mut Vec, name: &str, value: u64) { buffer.clear(); write!(buffer, "{}: {}", name, value).unwrap(); std::io::stdout().write_all(buffer).unwrap(); } ``` --- ## 8. Testing & Validation ### Security Testing Commands ```bash cargo audit # Dependency vulnerabilities cargo +nightly careful test # Memory safety checking cargo clippy -- -D warnings # Lint with security warnings ``` ### Unit Test Pattern ```rust #[cfg(test)] mod tests { use super::*; #[test] fn test_path_traversal_blocked() { let base = Path::new("/app/data"); assert!(safe_path_join(base, "../etc/passwd").is_err()); assert!(safe_path_join(base, "user/file.txt").is_ok()); } #[test] fn test_command_allowlist() { assert!(safe_command("rm", &["-rf", "/"]).is_err()); assert!(safe_command("git", &["status"]).is_ok()); } } ``` > **See `references/advanced-patterns.md` for fuzzing and integration test patterns** --- ## 9. Common Mistakes & Anti-Patterns | Anti-Pattern | Problem | Solution | |--------------|---------|----------| | `.unwrap()` in production | Panics crash app | Use `?` with Result | | Unsafe without docs | Unverified invariants | Add `// SAFETY:` comments | | Shell command execution | Injection vulnerability | Use `Command::new()` directly | | Ignoring Clippy | Missed security lints | Run `cargo clippy -- -D warnings` | | Hardcoded credentials | Secrets in code | Use env vars or secure storage | ```rust // NEVER: Shell injection Command::new("sh").arg("-c").arg(format!("echo {}", user_input)); // ALWAYS: Direct execution Command::new("echo").arg(user_input); ``` --- ## 10. Pre-Implementation Checklist ### Phase 1: Before Writing Code - [ ] Write failing tests that define expected behavior - [ ] Review relevant CVEs for the feature area - [ ] Identify security boundaries (FFI, IPC, file system) - [ ] Plan error handling strategy with Result types - [ ] Check dependencies with `cargo audit` ### Phase 2: During Implementation - [ ] Run tests after each significant change - [ ] Document all unsafe blocks with `// SAFETY:` comments - [ ] Validate inputs at all boundaries (Tauri commands, FFI) - [ ] Use type system to enforce invariants (newtypes) - [ ] Apply performance patterns (zero-copy, iterators) - [ ] Ensure error messages don't leak internal details ### Phase 3: Before Committing - [ ] `cargo test` - all tests pass - [ ] `cargo clippy -- -D warnings` - no warnings - [ ] `cargo audit` - zero HIGH/CRITICAL vulnerabilities - [ ] No hardcoded secrets (grep for "password", "secret", "key") - [ ] Path operations use canonicalization and containment checks - [ ] Command execution uses allowlist, no shell - [ ] Panic handler configured for graceful shutdown - [ ] Logging configured (no secrets in logs) --- ## 11. Summary Your goal is to create Rust code that is: - **Memory Safe**: Leverage the borrow checker, minimize unsafe - **Type Safe**: Use the type system to prevent invalid states - **Performant**: Zero-cost abstractions, profile before optimizing - **Secure**: Validate at boundaries, handle errors safely **Critical Security Reminders**: 1. Upgrade to Rust 1.81.0+ to fix command injection CVEs 2. Run cargo-audit in CI/CD pipeline 3. Document SAFETY invariants for all unsafe blocks 4. Never use shell execution with user input 5. Canonicalize and validate all file paths > **For detailed examples and advanced patterns, see the `references/` directory**

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