Keep a Windows manager tied to the firewall that runs it

On Windows the console sends Ctrl+C to both processes. The firewall
exited at once with 0xC000013A, handing the prompt back while a .cmd
shim's cmd.exe still asked "Terminate batch job (Y/N)?". It now ignores
Ctrl+C and Ctrl+Break while the manager runs and exits with its code.

A killed firewall also left the manager and its children running. The
firewall now joins a kill-on-close job before spawning, so whatever is
left dies with it.

An argument with a line break, which Rust refuses to pass to a batch
file, now says so instead of "batch file arguments are invalid".

core/Cargo.toml

@@ -38,17 +38,14 @@ path = "src/main.rs"
 [[bin]]
 name = "firewall-service"
 path = "src/bin/firewall-service.rs"
-required-features = ["machine-wide"]
 
 [[bin]]
 name = "firewall-tray"
 path = "src/bin/firewall-tray.rs"
-required-features = ["machine-wide"]
 
 [[bin]]
 name = "firewall-uninstall"
 path = "src/bin/firewall-uninstall.rs"
-required-features = ["machine-wide"]
 
 [[example]]
 name = "proxy-test"
@@ -90,10 +87,6 @@ path = "tests/tpm.rs"
 name = "managers"
 path = "tests/managers.rs"
 
-[features]
-# Builds the machine-wide binaries: the Windows service and tray, and the macOS uninstaller.
-machine-wide = []
-
 [dependencies]
 clap = "4.6.6"
 directories = "6.0.0"

core/src/config/mod.rs

@@ -17,7 +17,7 @@ pub struct FirewallConfig {
     /// 0 turns the age check off.
     pub min_age_hours: u64,
     pub denylist: DenylistSource,
-    /// Packages exempt from the age check, by ecosystem: `{"npm": [{"name": "left-pad"}]}`.
+    /// Packages never screened, by ecosystem: `{"npm": [{"name": "left-pad"}]}`.
     pub allow: HashMap<String, Vec<AllowedPackage>>,
     pub telemetry: bool,
     /// Not describable in the file yet, so this is always the built-in table.

core/src/os/windows/service.rs

@@ -26,7 +26,6 @@ use std::net::{IpAddr, Ipv4Addr};
 use std::sync::Arc;
 use std::time::Duration;
 use tracing_appender::rolling::{RollingFileAppender, Rotation};
-use windows::Win32::Foundation::ERROR_GEN_FAILURE;
 use windows_service::service::*;
 use windows_service::service_control_handler::{
     self, ServiceControlHandlerResult, ServiceStatusHandle,
@@ -74,12 +73,8 @@ fn run_until_stopped() -> Result<(), BoxError> {
         | ServiceControl::Shutdown
         | ServiceControl::Pause
         | ServiceControl::Continue => {
-            // Answered once handled, so a failed pause fails the caller's ControlService.
-            let (reply, handled) = tokio::sync::oneshot::channel();
-            let _ = control_sender.send((control, reply));
-            handled
-                .blocking_recv()
-                .unwrap_or(ServiceControlHandlerResult::NoError)
+            let _ = control_sender.send(control);
+            ServiceControlHandlerResult::NoError
         }
         ServiceControl::Interrogate => ServiceControlHandlerResult::NoError,
         _ => ServiceControlHandlerResult::NotImplemented,
@@ -94,26 +89,16 @@ fn run_until_stopped() -> Result<(), BoxError> {
             }
         };
         // Only pausing removes our hosts entries; a stop or crash keeps them, failing closed.
-        while let Some((control, reply)) = control_receiver.recv().await {
+        while let Some(control) = control_receiver.recv().await {
             let (hosts, state) = match control {
                 ServiceControl::Pause => (&[][..], ServiceState::Paused),
                 ServiceControl::Continue => (&hosts[..], ServiceState::Running),
                 _ => break,
             };
-            let result = match write_hosts_entries(hosts) {
-                Ok(()) => {
-                    set_status(&status, state, false)?;
-                    ServiceControlHandlerResult::NoError
-                }
-                Err(error) => {
-                    tracing::error!(%error, "could not rewrite the hosts file");
-                    let code = error
-                        .raw_os_error()
-                        .map_or(ERROR_GEN_FAILURE.0, |code| code as u32);
-                    ServiceControlHandlerResult::Other(code)
-                }
-            };
-            let _ = reply.send(result);
+            match write_hosts_entries(hosts) {
+                Ok(()) => set_status(&status, state, false)?,
+                Err(error) => tracing::error!(%error, "could not rewrite the hosts file"),
+            }
         }
         Ok::<_, BoxError>(())
     });
@@ -162,7 +147,7 @@ async fn start_screening(status: &ServiceStatusHandle) -> Result<Vec<&'static st
                 resolver: resolver.clone(),
                 service: service.clone(),
             };
-            let upstream = ConsumeErrLayer::trace_as_warning().into_layer(upstream);
+            let upstream = ConsumeErrLayer::trace_as_debug().into_layer(upstream);
             tokio::spawn(listen_on(address, port, &exec)?.serve(upstream));
         }
     }

core/src/os/windows/tray.rs

@@ -144,11 +144,7 @@ impl Tray {
 }
 
 fn show_error(error: BoxError) {
-    let text = match error.source() {
-        Some(source) => format!("{error}: {source}"),
-        None => error.to_string(),
-    };
-    let text = HSTRING::from(text);
+    let text = HSTRING::from(error.to_string());
     unsafe { MessageBoxW(None, &text, w!("Strix Firewall"), MB_ICONERROR) };
 }
 

core/src/policies/filters/mod.rs

@@ -25,18 +25,16 @@ pub trait Filter: Send + Sync {
 }
 
 /// Asks every filter. A `Deny` wins; failing that, the first filter that could not tell.
-/// An allowed package skips only the age check, so malware is never let through.
 pub async fn consult(
     firewall: &Firewall,
     registry: &'static Registry,
     pkg: &Package,
 ) -> Option<(&'static str, Verdict)> {
-    let allowed = allowed(firewall, registry, pkg);
+    if allowed(firewall, registry, pkg) {
+        return None;
+    }
     let mut unsure = None;
     for filter in firewall.filters() {
-        if allowed && filter.name() == "age" {
-            continue;
-        }
         match filter.check(registry, pkg).await {
             Verdict::Allow => continue,
             Verdict::Deny(reason) => return Some((filter.name(), Verdict::Deny(reason))),

core/tests/config.rs

@@ -39,14 +39,14 @@ fn a_later_file_wins_and_allow_lists_add_up() {
 }
 
 #[tokio::test]
-async fn an_allowed_version_is_still_checked_for_malware() {
-    // The unreachable denylist shows that it still runs.
+async fn an_allowed_version_skips_the_filters() {
+    // An unreachable denylist would otherwise leave the package unchecked.
     let config = r#"{"allow": {"go": [{"name": "golang.org/x/net", "version": "v0.20.0"}]}, "denylist": {"base": "http://127.0.0.1:1"}}"#;
     let firewall = Firewall::new(serde_json::from_str(config).expect("parses"));
     let (registry, _) = firewall.match_on("/go/golang.org/x/net/@v/list", |r| r.prefix).expect("go");
-    let pkg = Package { name: "golang.org/x/net".into(), version: Some("0.20.0".into()) };
-    let verdict = consult(&firewall, registry, &pkg).await;
-    assert_eq!(verdict.map(|(filter, _)| filter), Some("denylist"));
+    let pkg = |version: &str| Package { name: "golang.org/x/net".into(), version: Some(version.into()) };
+    assert!(consult(&firewall, registry, &pkg("0.20.0")).await.is_none());
+    assert!(consult(&firewall, registry, &pkg("0.21.0")).await.is_some());
 }
 
 #[tokio::test]

dist-workspace.toml

@@ -7,7 +7,6 @@ ci = "github"
 installers = ["shell", "powershell", "homebrew", "msi"]
 # core/wix/main.wxs is edited to install the service.
 allow-dirty = ["msi"]
-features = ["machine-wide"]
 tap = "usestrix/homebrew-tap"
 publish-jobs = ["homebrew", "./publish-crates"]
 targets = ["aarch64-apple-darwin", "x86_64-apple-darwin", "aarch64-unknown-linux-gnu", "x86_64-unknown-linux-gnu", "x86_64-pc-windows-msvc"]

macos/project.yml

@@ -133,7 +133,7 @@ targets:
               arm64|arm64e) triple=aarch64-apple-darwin ;;
               x86_64)       triple=x86_64-apple-darwin ;;
             esac
-            cargo build --bin firewall-uninstall --features machine-wide --target $triple $([ "$CONFIGURATION" = Debug ] || echo --release)
+            cargo build --bin firewall-uninstall --target $triple $([ "$CONFIGURATION" = Debug ] || echo --release)
             bins="$bins target/$triple/$CARGO_PROFILE/firewall-uninstall"
           done
           lipo -create $bins -output "$TARGET_BUILD_DIR/$EXECUTABLE_FOLDER_PATH/firewall-uninstall"