mvm-core 0.13.0

use serde::{Deserialize, Serialize};

use crate::signing::SignedPayload;

/// Current authenticated protocol version.
pub const PROTOCOL_VERSION_AUTHENTICATED: u8 = 2;

/// Legacy unauthenticated protocol version.
pub const PROTOCOL_VERSION_LEGACY: u8 = 1;

// ============================================================================
// Authenticated vsock frames
// ============================================================================

/// A versioned, signed vsock frame envelope.
///
/// After the initial CONNECT/OK handshake and session establishment,
/// every frame becomes an `AuthenticatedFrame` containing the Ed25519-signed
/// inner payload (the original `GuestRequest` or `GuestResponse` JSON).
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AuthenticatedFrame {
    /// Protocol version (2 = authenticated, 1 = legacy/unauthenticated).
    pub version: u8,
    /// Unique per-session identifier (assigned during handshake).
    pub session_id: String,
    /// Monotonically increasing sequence number for replay detection.
    pub sequence: u64,
    /// ISO 8601 timestamp of frame creation.
    pub timestamp: String,
    /// The Ed25519-signed inner payload.
    pub signed: SignedPayload,
}

// ============================================================================
// Session handshake
// ============================================================================

/// Host → Guest: initiate authenticated session after CONNECT/OK.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SessionHello {
    /// Protocol version the host supports.
    pub version: u8,
    /// Session identifier (UUID v4, generated by host).
    pub session_id: String,
    /// Random challenge bytes (32 bytes) the guest must sign to prove key possession.
    pub challenge: Vec<u8>,
    /// Host's Ed25519 public key (32 bytes) for the guest to verify host frames.
    pub host_pubkey: Vec<u8>,
}

/// Guest → Host: acknowledge session and prove key possession.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SessionHelloAck {
    /// Protocol version the guest supports.
    pub version: u8,
    /// Echo back the session identifier.
    pub session_id: String,
    /// Signed challenge bytes proving the guest holds the session key.
    pub challenge_response: Vec<u8>,
    /// Guest's Ed25519 public key (32 bytes) for the host to verify guest frames.
    pub guest_pubkey: Vec<u8>,
}

// ============================================================================
// Security policy
// ============================================================================

/// Per-VM security configuration, provisioned on the config drive.
///
/// Controls authentication requirements, access permissions, rate limiting,
/// and session lifecycle. Immutable after VM boot.
///
/// **Default: `require_auth = true`** — authentication is required unless
/// explicitly opted out for dev/testing via `SecurityPolicy::dev_defaults()`.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SecurityPolicy {
    /// Require authenticated vsock frames. Default: true.
    /// Set to false only for dev/testing environments.
    #[serde(default = "default_true")]
    pub require_auth: bool,

    /// Access control toggles.
    #[serde(default)]
    pub access: AccessPolicy,

    /// Frame rate limiting configuration.
    #[serde(default)]
    pub rate_limits: RateLimitPolicy,

    /// Session lifecycle limits.
    #[serde(default)]
    pub session: SessionPolicy,

    /// Command blocklist entries for the gate.
    #[serde(default)]
    pub blocklist: Vec<BlocklistEntry>,
}

impl Default for SecurityPolicy {
    fn default() -> Self {
        Self {
            require_auth: true,
            access: AccessPolicy::default(),
            rate_limits: RateLimitPolicy::default(),
            session: SessionPolicy::default(),
            blocklist: Vec::new(),
        }
    }
}

impl SecurityPolicy {
    /// Permissive defaults for development and testing environments.
    /// Authentication is disabled and console access is enabled.
    pub fn dev_defaults() -> Self {
        Self {
            require_auth: false,
            access: AccessPolicy {
                console: true,
                debug_exec: true,
                ..AccessPolicy::default()
            },
            ..Self::default()
        }
    }
}

/// Access control toggles for guest operations.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AccessPolicy {
    /// Allow filesystem operations.
    #[serde(default = "default_true")]
    pub filesystem: bool,

    /// Allow outbound network access.
    #[serde(default = "default_true")]
    pub network: bool,

    /// Allow Nix build operations.
    #[serde(default = "default_true")]
    pub build: bool,

    /// Allow host communication (host-bound vsock requests).
    #[serde(default = "default_true")]
    pub host_communication: bool,

    /// Allow debug command execution via vsock (dev-only, disabled by default).
    #[serde(default)]
    pub debug_exec: bool,

    /// Allow interactive PTY console sessions (dev-only, disabled by default).
    #[serde(default)]
    pub console: bool,
}

impl Default for AccessPolicy {
    fn default() -> Self {
        Self {
            filesystem: true,
            network: true,
            build: true,
            host_communication: true,
            debug_exec: false,
            console: false,
        }
    }
}

/// Frame rate limiting configuration.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RateLimitPolicy {
    /// Maximum frames per second (0 = unlimited).
    #[serde(default = "default_rate_fps")]
    pub frames_per_second: u32,

    /// Maximum frames per minute (0 = unlimited).
    #[serde(default = "default_rate_fpm")]
    pub frames_per_minute: u32,
}

impl Default for RateLimitPolicy {
    fn default() -> Self {
        Self {
            frames_per_second: 100,
            frames_per_minute: 3000,
        }
    }
}

/// Session lifecycle limits.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct SessionPolicy {
    /// Maximum session lifetime in seconds (0 = unlimited).
    #[serde(default)]
    pub max_lifetime_secs: u64,

    /// Maximum tasks per session before recycling (0 = unlimited).
    #[serde(default)]
    pub max_tasks: u64,
}

// ============================================================================
// Command gating
// ============================================================================

/// Decision from the command gate after evaluating a vsock command.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum GateDecision {
    /// Command is allowed to proceed.
    Allow,
    /// Command matched a blocklist entry and is blocked.
    Blocked {
        /// The pattern that matched.
        pattern: String,
        /// Human-readable reason for blocking.
        reason: String,
    },
    /// Command requires explicit approval before proceeding.
    RequiresApproval {
        /// Human-readable reason approval is needed.
        reason: String,
    },
}

/// Verdict from an approval authority (coordinator or dev-mode auto-approve).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum ApprovalVerdict {
    /// Approved to proceed.
    Approved,
    /// Denied with reason.
    Denied { reason: String },
    /// Timed out waiting for approval.
    Timeout,
}

/// Action to take when a blocklist entry matches.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum BlocklistAction {
    /// Block the command immediately.
    Block,
    /// Hold for approval before proceeding.
    RequireApproval,
    /// Log the match but allow the command.
    Log,
}

/// Severity level for blocklist entries.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
pub enum BlocklistSeverity {
    Low,
    Medium,
    High,
    Critical,
}

/// A single blocklist entry for command gating.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct BlocklistEntry {
    /// Pattern to match (literal string or glob with `*`/`?` wildcards).
    pub pattern: String,
    /// Category of the threat (e.g., "destructive", "exfiltration").
    pub category: String,
    /// Severity of the matched command.
    pub severity: BlocklistSeverity,
    /// Action to take when the pattern matches.
    pub action: BlocklistAction,
}

// ============================================================================
// Threat classification
// ============================================================================

/// Threat categories for vsock message classification.
///
/// Each category represents a class of security concern. A single message
/// may trigger findings across multiple categories.
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum ThreatCategory {
    /// Credential or secret exposure (API keys, tokens, private keys).
    SecretExposure,
    /// Data exfiltration to external endpoints.
    DataExfiltration,
    /// Shell injection or code injection attempts.
    Injection,
    /// Destructive commands (rm -rf, mkfs, DROP TABLE).
    Destructive,
    /// Privilege escalation (sudo, nsenter, setuid).
    PrivilegeEscalation,
    /// Supply chain attacks (untrusted installs, impure builds).
    SupplyChain,
    /// Access to sensitive system files.
    SensitiveFileAccess,
    /// System configuration modification.
    SystemModification,
    /// Network abuse (port scanning, reverse shells).
    NetworkAbuse,
    /// MicroVM/Firecracker escape and tool poisoning.
    ToolPoisoning,
}

/// Severity of a threat finding.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
pub enum Severity {
    Info,
    Low,
    Medium,
    High,
    Critical,
}

/// A single threat finding produced by the classifier.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ThreatFinding {
    /// Threat category.
    pub category: ThreatCategory,
    /// Identifier for the pattern that matched (e.g., "aws_access_key", "rm_rf_root").
    pub pattern_id: String,
    /// Severity of this finding.
    pub severity: Severity,
    /// The text that matched (or a representative snippet).
    pub matched_text: String,
    /// Additional context about the finding.
    pub context: String,
}

// ============================================================================
// Security posture
// ============================================================================

/// A security layer that can be evaluated for posture scoring.
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum SecurityLayer {
    JailerIsolation,
    CgroupLimits,
    SeccompFilter,
    NetworkIsolation,
    VsockAuth,
    EncryptionAtRest,
    EncryptionInTransit,
    AuditLogging,
    SecretManagement,
    ConfigImmutability,
    GuestHardening,
    SupplyChainIntegrity,
}

impl SecurityLayer {
    /// All security layers in evaluation order.
    pub fn all() -> &'static [SecurityLayer] {
        &[
            SecurityLayer::JailerIsolation,
            SecurityLayer::CgroupLimits,
            SecurityLayer::SeccompFilter,
            SecurityLayer::NetworkIsolation,
            SecurityLayer::VsockAuth,
            SecurityLayer::EncryptionAtRest,
            SecurityLayer::EncryptionInTransit,
            SecurityLayer::AuditLogging,
            SecurityLayer::SecretManagement,
            SecurityLayer::ConfigImmutability,
            SecurityLayer::GuestHardening,
            SecurityLayer::SupplyChainIntegrity,
        ]
    }
}

/// Result of a single posture check.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PostureCheck {
    /// Which security layer this check belongs to.
    pub layer: SecurityLayer,
    /// Human-readable check name (e.g., "Jailer enabled for Firecracker").
    pub name: String,
    /// Whether the check passed.
    pub passed: bool,
    /// Explanation of the result.
    pub detail: String,
}

/// Overall posture report aggregating all checks.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PostureReport {
    /// Individual check results.
    pub checks: Vec<PostureCheck>,
    /// Overall score: `passed_checks / total_checks * 100`.
    pub score: f64,
    /// ISO 8601 timestamp of when the report was generated.
    pub timestamp: String,
}

fn default_true() -> bool {
    true
}

fn default_rate_fps() -> u32 {
    100
}

fn default_rate_fpm() -> u32 {
    3000
}

// ============================================================================
// Tests
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_authenticated_frame_serde_roundtrip() {
        let frame = AuthenticatedFrame {
            version: PROTOCOL_VERSION_AUTHENTICATED,
            session_id: "sess-001".to_string(),
            sequence: 42,
            timestamp: "2026-02-25T00:00:00Z".to_string(),
            signed: SignedPayload {
                payload: b"inner request json".to_vec(),
                signature: vec![0u8; 64],
                signer_id: "guest-key-1".to_string(),
            },
        };

        let json = serde_json::to_string(&frame).unwrap();
        let parsed: AuthenticatedFrame = serde_json::from_str(&json).unwrap();

        assert_eq!(parsed.version, 2);
        assert_eq!(parsed.session_id, "sess-001");
        assert_eq!(parsed.sequence, 42);
        assert_eq!(parsed.signed.payload, b"inner request json");
        assert_eq!(parsed.signed.signature.len(), 64);
    }

    #[test]
    fn test_session_hello_serde_roundtrip() {
        let hello = SessionHello {
            version: PROTOCOL_VERSION_AUTHENTICATED,
            session_id: "sess-002".to_string(),
            challenge: vec![1, 2, 3, 4, 5],
            host_pubkey: vec![0u8; 32],
        };

        let json = serde_json::to_string(&hello).unwrap();
        let parsed: SessionHello = serde_json::from_str(&json).unwrap();

        assert_eq!(parsed.version, 2);
        assert_eq!(parsed.session_id, "sess-002");
        assert_eq!(parsed.challenge.len(), 5);
        assert_eq!(parsed.host_pubkey.len(), 32);
    }

    #[test]
    fn test_session_hello_ack_serde_roundtrip() {
        let ack = SessionHelloAck {
            version: PROTOCOL_VERSION_AUTHENTICATED,
            session_id: "sess-002".to_string(),
            challenge_response: vec![9; 64],
            guest_pubkey: vec![0u8; 32],
        };

        let json = serde_json::to_string(&ack).unwrap();
        let parsed: SessionHelloAck = serde_json::from_str(&json).unwrap();

        assert_eq!(parsed.version, 2);
        assert_eq!(parsed.session_id, "sess-002");
        assert_eq!(parsed.challenge_response.len(), 64);
        assert_eq!(parsed.guest_pubkey.len(), 32);
    }

    #[test]
    fn test_security_policy_defaults() {
        let policy = SecurityPolicy::default();

        assert!(policy.require_auth);
        assert!(policy.access.filesystem);
        assert!(policy.access.network);
        assert!(policy.access.build);
        assert!(policy.access.host_communication);
        assert!(!policy.access.debug_exec);
        assert_eq!(policy.rate_limits.frames_per_second, 100);
        assert_eq!(policy.rate_limits.frames_per_minute, 3000);
        assert_eq!(policy.session.max_lifetime_secs, 0);
        assert_eq!(policy.session.max_tasks, 0);
    }

    #[test]
    fn test_security_policy_serde_with_defaults() {
        // Deserialize a minimal JSON — all fields should fill with defaults.
        let json = "{}";
        let policy: SecurityPolicy = serde_json::from_str(json).unwrap();

        assert!(policy.require_auth);
        assert!(policy.access.filesystem);
        assert_eq!(policy.rate_limits.frames_per_second, 100);
    }

    #[test]
    fn test_security_policy_serde_override() {
        let json = r#"{
            "require_auth": true,
            "access": { "build": false, "network": false },
            "rate_limits": { "frames_per_second": 50 }
        }"#;
        let policy: SecurityPolicy = serde_json::from_str(json).unwrap();

        assert!(policy.require_auth);
        assert!(policy.access.filesystem); // default
        assert!(!policy.access.build);
        assert!(!policy.access.network);
        assert_eq!(policy.rate_limits.frames_per_second, 50);
        assert_eq!(policy.rate_limits.frames_per_minute, 3000); // default
    }

    #[test]
    fn test_security_policy_full_roundtrip() {
        let policy = SecurityPolicy {
            require_auth: true,
            access: AccessPolicy {
                filesystem: false,
                network: true,
                build: false,
                host_communication: true,
                debug_exec: true,
                console: false,
            },
            rate_limits: RateLimitPolicy {
                frames_per_second: 200,
                frames_per_minute: 6000,
            },
            session: SessionPolicy {
                max_lifetime_secs: 3600,
                max_tasks: 100,
            },
            blocklist: vec![BlocklistEntry {
                pattern: "rm -rf /".to_string(),
                category: "destructive".to_string(),
                severity: BlocklistSeverity::Critical,
                action: BlocklistAction::Block,
            }],
        };

        let json = serde_json::to_string(&policy).unwrap();
        let parsed: SecurityPolicy = serde_json::from_str(&json).unwrap();

        assert!(parsed.require_auth);
        assert!(!parsed.access.filesystem);
        assert!(!parsed.access.build);
        assert!(parsed.access.debug_exec);
        assert_eq!(parsed.rate_limits.frames_per_second, 200);
        assert_eq!(parsed.session.max_lifetime_secs, 3600);
        assert_eq!(parsed.session.max_tasks, 100);
        assert_eq!(parsed.blocklist.len(), 1);
        assert_eq!(parsed.blocklist[0].pattern, "rm -rf /");
    }

    #[test]
    fn test_protocol_version_constants() {
        assert_eq!(PROTOCOL_VERSION_AUTHENTICATED, 2);
        assert_eq!(PROTOCOL_VERSION_LEGACY, 1);
    }

    #[test]
    fn test_gate_decision_serde_roundtrip() {
        let decisions = vec![
            GateDecision::Allow,
            GateDecision::Blocked {
                pattern: "rm -rf /".to_string(),
                reason: "destructive".to_string(),
            },
            GateDecision::RequiresApproval {
                reason: "matched pattern: nsenter".to_string(),
            },
        ];

        for decision in decisions {
            let json = serde_json::to_string(&decision).unwrap();
            let parsed: GateDecision = serde_json::from_str(&json).unwrap();
            assert_eq!(parsed, decision);
        }
    }

    #[test]
    fn test_approval_verdict_serde_roundtrip() {
        let verdicts = vec![
            ApprovalVerdict::Approved,
            ApprovalVerdict::Denied {
                reason: "policy violation".to_string(),
            },
            ApprovalVerdict::Timeout,
        ];

        for verdict in verdicts {
            let json = serde_json::to_string(&verdict).unwrap();
            let parsed: ApprovalVerdict = serde_json::from_str(&json).unwrap();
            assert_eq!(parsed, verdict);
        }
    }

    #[test]
    fn test_blocklist_entry_serde_roundtrip() {
        let entry = BlocklistEntry {
            pattern: "rm -rf /".to_string(),
            category: "destructive".to_string(),
            severity: BlocklistSeverity::Critical,
            action: BlocklistAction::Block,
        };

        let json = serde_json::to_string(&entry).unwrap();
        let parsed: BlocklistEntry = serde_json::from_str(&json).unwrap();
        assert_eq!(parsed.pattern, "rm -rf /");
        assert_eq!(parsed.severity, BlocklistSeverity::Critical);
        assert_eq!(parsed.action, BlocklistAction::Block);
    }

    #[test]
    fn test_blocklist_severity_ordering() {
        assert!(BlocklistSeverity::Low < BlocklistSeverity::Medium);
        assert!(BlocklistSeverity::Medium < BlocklistSeverity::High);
        assert!(BlocklistSeverity::High < BlocklistSeverity::Critical);
    }

    #[test]
    fn test_blocklist_action_values() {
        let actions = vec![
            BlocklistAction::Block,
            BlocklistAction::RequireApproval,
            BlocklistAction::Log,
        ];
        for action in actions {
            let json = serde_json::to_string(&action).unwrap();
            let parsed: BlocklistAction = serde_json::from_str(&json).unwrap();
            assert_eq!(parsed, action);
        }
    }

    #[test]
    fn test_security_policy_with_blocklist() {
        let json = r#"{
            "require_auth": true,
            "blocklist": [
                {
                    "pattern": "rm -rf /",
                    "category": "destructive",
                    "severity": "Critical",
                    "action": "Block"
                }
            ]
        }"#;
        let policy: SecurityPolicy = serde_json::from_str(json).unwrap();

        assert!(policy.require_auth);
        assert_eq!(policy.blocklist.len(), 1);
        assert_eq!(policy.blocklist[0].pattern, "rm -rf /");
        assert_eq!(policy.blocklist[0].action, BlocklistAction::Block);
    }

    #[test]
    fn test_security_policy_empty_blocklist_default() {
        let json = "{}";
        let policy: SecurityPolicy = serde_json::from_str(json).unwrap();
        assert!(policy.blocklist.is_empty());
    }

    // -- Threat classification tests --

    #[test]
    fn test_threat_category_serde_roundtrip() {
        let categories = vec![
            ThreatCategory::SecretExposure,
            ThreatCategory::DataExfiltration,
            ThreatCategory::Injection,
            ThreatCategory::Destructive,
            ThreatCategory::PrivilegeEscalation,
            ThreatCategory::SupplyChain,
            ThreatCategory::SensitiveFileAccess,
            ThreatCategory::SystemModification,
            ThreatCategory::NetworkAbuse,
            ThreatCategory::ToolPoisoning,
        ];
        for cat in categories {
            let json = serde_json::to_string(&cat).unwrap();
            let parsed: ThreatCategory = serde_json::from_str(&json).unwrap();
            assert_eq!(parsed, cat);
        }
    }

    #[test]
    fn test_severity_ordering() {
        assert!(Severity::Info < Severity::Low);
        assert!(Severity::Low < Severity::Medium);
        assert!(Severity::Medium < Severity::High);
        assert!(Severity::High < Severity::Critical);
    }

    #[test]
    fn test_severity_serde_roundtrip() {
        let severities = vec![
            Severity::Info,
            Severity::Low,
            Severity::Medium,
            Severity::High,
            Severity::Critical,
        ];
        for sev in severities {
            let json = serde_json::to_string(&sev).unwrap();
            let parsed: Severity = serde_json::from_str(&json).unwrap();
            assert_eq!(parsed, sev);
        }
    }

    #[test]
    fn test_threat_finding_serde_roundtrip() {
        let finding = ThreatFinding {
            category: ThreatCategory::SecretExposure,
            pattern_id: "aws_access_key".to_string(),
            severity: Severity::Critical,
            matched_text: "AKIAIOSFODNN7EXAMPLE".to_string(),
            context: "AWS access key detected".to_string(),
        };

        let json = serde_json::to_string(&finding).unwrap();
        let parsed: ThreatFinding = serde_json::from_str(&json).unwrap();
        assert_eq!(parsed.category, ThreatCategory::SecretExposure);
        assert_eq!(parsed.pattern_id, "aws_access_key");
        assert_eq!(parsed.severity, Severity::Critical);
    }

    // -- Posture types --

    #[test]
    fn test_security_layer_all_count() {
        assert_eq!(SecurityLayer::all().len(), 12);
    }

    #[test]
    fn test_security_layer_serde_roundtrip() {
        for layer in SecurityLayer::all() {
            let json = serde_json::to_string(layer).unwrap();
            let parsed: SecurityLayer = serde_json::from_str(&json).unwrap();
            assert_eq!(&parsed, layer);
        }
    }

    #[test]
    fn test_posture_check_serde_roundtrip() {
        let check = PostureCheck {
            layer: SecurityLayer::JailerIsolation,
            name: "Jailer enabled".to_string(),
            passed: true,
            detail: "Firecracker runs inside jailer".to_string(),
        };
        let json = serde_json::to_string(&check).unwrap();
        let parsed: PostureCheck = serde_json::from_str(&json).unwrap();
        assert_eq!(parsed.layer, SecurityLayer::JailerIsolation);
        assert!(parsed.passed);
    }

    #[test]
    fn test_posture_report_serde_roundtrip() {
        let report = PostureReport {
            checks: vec![
                PostureCheck {
                    layer: SecurityLayer::CgroupLimits,
                    name: "cgroup v2 limits set".to_string(),
                    passed: true,
                    detail: "mem + cpu limits configured".to_string(),
                },
                PostureCheck {
                    layer: SecurityLayer::VsockAuth,
                    name: "vsock auth enabled".to_string(),
                    passed: false,
                    detail: "require_auth is false".to_string(),
                },
            ],
            score: 50.0,
            timestamp: "2026-02-25T00:00:00Z".to_string(),
        };
        let json = serde_json::to_string(&report).unwrap();
        let parsed: PostureReport = serde_json::from_str(&json).unwrap();
        assert_eq!(parsed.checks.len(), 2);
        assert_eq!(parsed.score, 50.0);
    }
}