vtcode_safety/sandboxing/

manager.rs

//! Sandbox manager for transforming commands into sandboxed execution environments.

use std::ffi::OsString;
use std::path::Path;

use super::exec_env::{CommandSpec, ExecEnv, SandboxType};
#[cfg(target_os = "macos")]
use super::policy::NetworkAllowlistEntry;
use super::policy::SandboxPolicy;

/// Error type for sandbox transformation failures.
#[derive(Debug, thiserror::Error)]
pub enum SandboxTransformError {
    #[error("missing sandbox executable path")]
    MissingSandboxExecutable,

    #[error("sandbox type {0:?} is not available on this platform")]
    UnavailableSandboxType(SandboxType),

    #[error("failed to create sandbox environment: {0}")]
    CreationFailed(String),

    #[error("invalid sandbox policy: {0}")]
    InvalidPolicy(String),
}

/// Manager for sandbox transformation.
///
/// Transforms a `CommandSpec` into an `ExecEnv` by applying the appropriate
/// sandbox wrapper based on the platform and policy.
#[derive(Debug, Default)]
pub struct SandboxManager;

impl SandboxManager {
    /// Create a new sandbox manager.
    pub fn new() -> Self {
        Self
    }

    /// Transform a command specification into a sandboxed execution environment.
    pub fn transform(
        &self,
        spec: CommandSpec,
        policy: &SandboxPolicy,
        sandbox_cwd: &Path,
        sandbox_executable: Option<&Path>,
    ) -> Result<ExecEnv, SandboxTransformError> {
        // Determine the sandbox type based on policy and platform
        let sandbox_type = self.determine_sandbox_type(policy)?;

        // If no sandbox needed or full access, return direct execution
        if sandbox_type == SandboxType::None {
            return Ok(ExecEnv {
                program: spec.program.into(),
                args: spec.args,
                cwd: spec.cwd,
                env: spec.env,
                expiration: spec.expiration,
                sandbox_active: false,
                sandbox_type: SandboxType::None,
            });
        }

        // Check sandbox availability
        if !sandbox_type.is_available() {
            return Err(SandboxTransformError::UnavailableSandboxType(sandbox_type));
        }

        // Transform based on sandbox type
        match sandbox_type {
            SandboxType::MacosSeatbelt => self.transform_seatbelt(spec, policy, sandbox_cwd),
            SandboxType::LinuxLandlock => self.transform_landlock(spec, policy, sandbox_cwd, sandbox_executable),
            SandboxType::WindowsRestrictedToken => self.transform_windows(spec, policy, sandbox_cwd),
            SandboxType::None => {
                Err(SandboxTransformError::InvalidPolicy("Cannot transform with SandboxType::None".into()))
            }
        }
    }

    /// Determine the appropriate sandbox type for the given policy.
    fn determine_sandbox_type(&self, policy: &SandboxPolicy) -> Result<SandboxType, SandboxTransformError> {
        match policy {
            SandboxPolicy::DangerFullAccess | SandboxPolicy::ExternalSandbox { .. } => Ok(SandboxType::None),
            SandboxPolicy::ReadOnly { .. } | SandboxPolicy::WorkspaceWrite { .. } => {
                Ok(SandboxType::platform_default())
            }
        }
    }

    /// Transform for macOS Seatbelt sandbox.
    #[cfg(target_os = "macos")]
    fn transform_seatbelt(
        &self,
        spec: CommandSpec,
        policy: &SandboxPolicy,
        sandbox_cwd: &Path,
    ) -> Result<ExecEnv, SandboxTransformError> {
        const SEATBELT_EXECUTABLE: &str = "/usr/bin/sandbox-exec";

        // Build the seatbelt profile
        let profile = self.build_seatbelt_profile(policy, sandbox_cwd);

        let mut args = vec!["-p".to_string(), profile, os_string_to_arg(spec.program.clone())];
        args.extend(spec.args);

        Ok(ExecEnv {
            program: SEATBELT_EXECUTABLE.into(),
            args,
            cwd: spec.cwd,
            env: spec.env,
            expiration: spec.expiration,
            sandbox_active: true,
            sandbox_type: SandboxType::MacosSeatbelt,
        })
    }

    #[cfg(not(target_os = "macos"))]
    fn transform_seatbelt(
        &self,
        _spec: CommandSpec,
        _policy: &SandboxPolicy,
        _sandbox_cwd: &Path,
    ) -> Result<ExecEnv, SandboxTransformError> {
        Err(SandboxTransformError::UnavailableSandboxType(SandboxType::MacosSeatbelt))
    }

    /// Build a seatbelt profile string.
    ///
    /// Implements the field guide's recommendations:
    /// - "Default-deny outbound network, then allowlist."
    /// - Block sensitive paths to prevent credential leakage.
    #[cfg(target_os = "macos")]
    fn build_seatbelt_profile(&self, policy: &SandboxPolicy, sandbox_cwd: &Path) -> String {
        fn append_network_rules(
            profile: &mut String,
            network_access: bool,
            network_allowlist: &[NetworkAllowlistEntry],
        ) {
            let has_network_allowlist = !network_allowlist.is_empty();
            if has_network_allowlist || !network_access {
                // Keep local unix sockets available even when outbound network is restricted.
                profile.push_str("(allow network* (local unix))\n");
            }
            if has_network_allowlist {
                for entry in network_allowlist {
                    profile.push_str(&format!(
                        "(allow network-outbound (remote {} (require-any (port {}))))\n",
                        entry.protocol, entry.port
                    ));
                }
                profile.push_str("(allow network-outbound (remote udp (port 53)))\n");
                profile.push_str("(allow network-outbound (remote tcp (port 53)))\n");
            } else if network_access {
                profile.push_str("(allow network*)\n");
            }
        }

        let mut profile = String::from("(version 1)\n");
        profile.push_str("(deny default)\n");
        profile.push_str("(allow process-exec)\n");
        profile.push_str("(allow process-fork)\n");
        profile.push_str("(allow sysctl-read)\n");
        profile.push_str("(allow mach-lookup)\n");
        profile.push_str("(allow ipc-posix-shm-read* (ipc-posix-name-prefix \"apple.cfprefs.\"))\n");
        profile.push_str("(allow mach-lookup (global-name \"com.apple.cfprefsd.daemon\") (global-name \"com.apple.cfprefsd.agent\") (local-name \"com.apple.cfprefsd.agent\"))\n");
        profile.push_str("(allow user-preference-read)\n");

        // Block sensitive paths BEFORE allowing general read access
        // This ensures deny rules take precedence
        let sensitive_paths = policy.sensitive_paths_for_execution(sandbox_cwd);
        for sp in &sensitive_paths {
            let expanded = sp.expand_path();
            let path_str = expanded.display();
            if sp.block_read {
                profile.push_str(&format!("(deny file-read* (subpath \"{path_str}\"))\n"));
            }
            if sp.block_write {
                profile.push_str(&format!("(deny file-write* (subpath \"{path_str}\"))\n"));
            }
        }

        // Allow reading from everywhere (except denied sensitive paths above)
        profile.push_str("(allow file-read*)\n");

        match policy {
            SandboxPolicy::ReadOnly { network_access, network_allowlist } => {
                // Read-only: only allow writing to /dev/null
                profile.push_str("(allow file-write* (literal \"/dev/null\"))\n");
                append_network_rules(&mut profile, *network_access, network_allowlist);
            }
            SandboxPolicy::WorkspaceWrite { network_access, network_allowlist, .. } => {
                for root in policy.get_writable_roots_with_cwd(sandbox_cwd) {
                    let path = root.root.display();
                    profile.push_str(&format!("(allow file-write* (subpath \"{path}\"))\n"));
                }
                append_network_rules(&mut profile, *network_access, network_allowlist);
            }
            _ => {}
        }

        profile
    }

    /// Transform for Linux Landlock sandbox.
    ///
    /// Following the field guide: "Landlock + seccomp is the recommended Linux pattern."
    /// The sandbox helper binary receives both the policy (for Landlock filesystem rules)
    /// and the seccomp profile (for syscall filtering).
    fn transform_landlock(
        &self,
        spec: CommandSpec,
        policy: &SandboxPolicy,
        sandbox_cwd: &Path,
        sandbox_executable: Option<&Path>,
    ) -> Result<ExecEnv, SandboxTransformError> {
        let sandbox_exe = sandbox_executable.ok_or(SandboxTransformError::MissingSandboxExecutable)?;

        // Serialize the policy for the sandbox helper (includes Landlock rules)
        let policy_json = serde_json::to_string(policy)
            .map_err(|e| SandboxTransformError::CreationFailed(format!("failed to serialize sandbox policy: {e}")))?;

        // Serialize seccomp profile separately for explicit syscall filtering
        let seccomp_profile = policy.seccomp_profile();
        let seccomp_json = seccomp_profile
            .to_json()
            .map_err(|e| SandboxTransformError::CreationFailed(format!("failed to serialize seccomp profile: {e}")))?;

        // Serialize resource limits for cgroup/rlimit enforcement
        let resource_limits = policy.resource_limits();
        let limits_json = serde_json::to_string(&resource_limits)
            .map_err(|e| SandboxTransformError::CreationFailed(format!("failed to serialize resource limits: {e}")))?;

        let sandbox_cwd_str = sandbox_cwd.to_string_lossy().to_string();

        let mut args = vec![
            "--sandbox-policy-cwd".to_string(),
            sandbox_cwd_str,
            "--sandbox-policy".to_string(),
            policy_json,
            "--seccomp-profile".to_string(),
            seccomp_json,
            "--resource-limits".to_string(),
            limits_json,
            "--".to_string(),
            os_string_to_arg(spec.program.clone()),
        ];
        args.extend(spec.args);

        Ok(ExecEnv {
            program: sandbox_exe.to_path_buf(),
            args,
            cwd: spec.cwd,
            env: spec.env,
            expiration: spec.expiration,
            sandbox_active: true,
            sandbox_type: SandboxType::LinuxLandlock,
        })
    }

    /// Transform for Windows restricted token sandbox.
    fn transform_windows(
        &self,
        spec: CommandSpec,
        _policy: &SandboxPolicy,
        _sandbox_cwd: &Path,
    ) -> Result<ExecEnv, SandboxTransformError> {
        // Windows sandbox uses restricted tokens - for now, pass through
        // A full implementation would use Windows job objects and restricted tokens
        Ok(ExecEnv {
            program: spec.program.into(),
            args: spec.args,
            cwd: spec.cwd,
            env: spec.env,
            expiration: spec.expiration,
            sandbox_active: false, // Windows sandboxing via Job Objects/Restricted Tokens is planned for a future release
            sandbox_type: SandboxType::WindowsRestrictedToken,
        })
    }
}

fn os_string_to_arg(value: OsString) -> String {
    value.into_string().unwrap_or_else(|value| value.to_string_lossy().into_owned())
}

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

    #[test]
    fn test_no_sandbox_for_full_access() {
        let manager = SandboxManager::new();
        let spec = CommandSpec::new("echo").with_args(vec!["hello"]);
        let policy = SandboxPolicy::full_access();

        let env = manager.transform(spec, &policy, Path::new("/tmp"), None).unwrap();

        assert!(!env.sandbox_active);
        assert_eq!(env.sandbox_type, SandboxType::None);
    }

    #[test]
    fn test_sandbox_type_determination() {
        let manager = SandboxManager::new();

        // Full access = no sandbox
        let result = manager.determine_sandbox_type(&SandboxPolicy::DangerFullAccess);
        assert_eq!(result.unwrap(), SandboxType::None);

        // Read-only = platform default
        let result = manager.determine_sandbox_type(&SandboxPolicy::read_only());
        assert_eq!(result.unwrap(), SandboxType::platform_default());
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn seatbelt_profile_includes_default_preferences_policy() {
        let manager = SandboxManager::new();
        let profile = manager.build_seatbelt_profile(&SandboxPolicy::read_only(), Path::new("/tmp"));

        assert!(profile.contains("(allow ipc-posix-shm-read* (ipc-posix-name-prefix \"apple.cfprefs.\"))"));
        assert!(profile.contains("(global-name \"com.apple.cfprefsd.daemon\")"));
        assert!(profile.contains("(global-name \"com.apple.cfprefsd.agent\")"));
        assert!(profile.contains("(local-name \"com.apple.cfprefsd.agent\")"));
        assert!(profile.contains("(allow user-preference-read)"));
    }
}