Show the Windows service's blocks from the tray

The service answers the tray's requests on a named pipe, as the macOS extension answers the app's messages. The tray asks for blocks every two seconds, pops each new one up and lists the last ten in its menu.

core/Cargo.toml

@@ -90,10 +90,6 @@ path = "tests/tpm.rs"
 name = "managers"
 path = "tests/managers.rs"
 
-[[test]]
-name = "blocks"
-path = "tests/blocks.rs"
-
 [features]
 # Builds the machine-wide binaries: the Windows service and tray, and the macOS uninstaller.
 machine-wide = []
@@ -129,7 +125,7 @@ schannel = "0.1.29"
 tokio = { version = "1.53.1", features = ["net"] }
 tracing-appender = "0.2.5"
 tray-icon = { version = "0.26.1", default-features = false }
-windows = { version = "0.62", features = ["Win32_Foundation", "Win32_Security", "Win32_Security_Authorization", "Win32_Security_Cryptography", "Win32_Storage_FileSystem", "Win32_System_Com", "Win32_System_Console", "Win32_System_Environment", "Win32_System_JobObjects", "Win32_System_Threading", "Win32_UI_Shell", "Win32_UI_WindowsAndMessaging"] }
+windows = { version = "0.62", features = ["Win32_Foundation", "Win32_Security", "Win32_Security_Authorization", "Win32_Security_Cryptography", "Win32_Storage_FileSystem", "Win32_System_Com", "Win32_System_Console", "Win32_System_Environment", "Win32_System_JobObjects", "Win32_System_Pipes", "Win32_System_Threading", "Win32_UI_Shell", "Win32_UI_WindowsAndMessaging"] }
 windows-registry = "0.6.1"
 windows-service = "0.8.0"
 

core/src/blocks.rs

@@ -1,25 +1,14 @@
-use crate::config::{self, AllowedPackage};
 use crate::policies::Package;
-use crate::Firewall;
-use rama::error::BoxError;
 use serde::Serialize;
-use std::path::Path;
 use std::sync::Mutex;
-use std::time::{Duration, Instant};
-use tokio::sync::watch;
 
-/// So blocks can't pile up while no app collects them.
+/// Bounded, so blocks pile up harmlessly while nothing collects them.
 const KEPT: usize = 50;
-/// Under pip's, pipenv's and pdm's 15 s read timeout, the shortest of the supported managers.
-const HOLD: Duration = Duration::from_secs(10);
-/// Only hold while an app is asking for blocks, so someone can answer.
-const WATCHED: Duration = Duration::from_secs(2);
-/// For a minute, so the rest of that install can fetch it too.
-const ONCE: Duration = Duration::from_secs(60);
 
-#[derive(Clone, Serialize)]
+static RECENT: Mutex<Vec<BlockedPackage>> = Mutex::new(Vec::new());
+
+#[derive(Serialize)]
 pub struct BlockedPackage {
-    pub id: u64,
     pub eco: &'static str,
     pub name: String,
     pub version: Option<String>,
@@ -27,125 +16,21 @@ pub struct BlockedPackage {
     pub reason: String,
 }
 
-struct Blocks {
-    last_id: u64,
-    unsent: Vec<BlockedPackage>,
-    /// Age holds, the only blocks that can be allowed, each with what wakes its waiting downloads.
-    held: Vec<(BlockedPackage, watch::Sender<bool>)>,
-    polled: Option<Instant>,
-}
-
-static BLOCKS: Mutex<Blocks> =
-    Mutex::new(Blocks { last_id: 0, unsent: Vec::new(), held: Vec::new(), polled: None });
-
-/// Records a block and holds a new package's download for up to `HOLD`. Returns whether it was allowed.
-pub async fn block(eco: &'static str, pkg: &Package, filter: &'static str, reason: &str) -> bool {
-    let Some(mut answer) = record(eco, pkg, filter, reason) else {
-        return false;
-    };
-    let allowed = tokio::time::timeout(HOLD, answer.wait_for(|allowed| *allowed)).await;
-    matches!(allowed, Ok(Ok(_)))
-}
-
-/// The app's requests: `blocks`, `allow <id>` or `allow-once <id>`.
-/// An allow replies `late` if the download had stopped waiting.
-pub fn answer(firewall: &Firewall, config: &Path, request: &str) -> String {
-    if request == "blocks" {
-        return serde_json::to_string(&take()).expect("blocks serialize");
+pub fn record(eco: &'static str, pkg: &Package, filter: &'static str, reason: &str) {
+    let mut recent = RECENT.lock().unwrap_or_else(|e| e.into_inner());
+    if recent.len() == KEPT {
+        recent.remove(0);
     }
-    let result = match request.split_once(' ').map(|(verb, id)| (verb, id.parse())) {
-        Some(("allow", Ok(id))) => trust(firewall, config, id),
-        Some(("allow-once", Ok(id))) => allow_once(firewall, id),
-        _ => Err(format!("unknown message {request}").into()),
-    };
-    match result {
-        Ok(true) => "ok".to_owned(),
-        Ok(false) => "late".to_owned(),
-        Err(error) => format!("error: {error}"),
-    }
-}
-
-/// Hands each block over once.
-fn take() -> Vec<BlockedPackage> {
-    let mut blocks = lock();
-    blocks.polled = Some(Instant::now());
-    std::mem::take(&mut blocks.unsent)
-}
-
-fn record(
-    eco: &'static str,
-    pkg: &Package,
-    filter: &'static str,
-    reason: &str,
-) -> Option<watch::Receiver<bool>> {
-    let mut blocks = lock();
-    let watched = blocks.polled.is_some_and(|polled| polled.elapsed() < WATCHED);
-    let holds = filter == "age" && watched;
-    // A repeat fetch of a held package waits on the same answer.
-    let waiting = blocks.held.iter().find(|(held, wake)| {
-        wake.receiver_count() > 0 && held.eco == eco && held.name == pkg.name && held.version == pkg.version
-    });
-    if let (true, Some((_, wake))) = (holds, waiting) {
-        return Some(wake.subscribe());
-    }
-    blocks.last_id += 1;
-    let block = BlockedPackage {
-        id: blocks.last_id,
+    recent.push(BlockedPackage {
         eco,
         name: pkg.name.clone(),
         version: pkg.version.clone(),
         filter,
         reason: reason.to_owned(),
-    };
-    push(&mut blocks.unsent, block.clone());
-    if filter != "age" {
-        return None;
-    }
-    let (wake, allowed) = watch::channel(false);
-    push(&mut blocks.held, (block, wake));
-    holds.then_some(allowed)
+    });
 }
 
-/// Also saved to the config, so it survives a restart.
-fn trust(firewall: &Firewall, config: &Path, id: u64) -> Result<bool, BoxError> {
-    let block = held(id)?;
-    let version = block.version.ok_or("only a version can be trusted")?;
-    config::allow(config, block.eco, &block.name, &version)?;
-    let package = AllowedPackage { name: block.name, version: Some(version) };
-    firewall.lift_age_check(block.eco, package, None);
-    Ok(release(id))
-}
-
-fn allow_once(firewall: &Firewall, id: u64) -> Result<bool, BoxError> {
-    let block = held(id)?;
-    let package = AllowedPackage { name: block.name, version: block.version };
-    firewall.lift_age_check(block.eco, package, Some(Instant::now() + ONCE));
-    Ok(release(id))
-}
-
-fn held(id: u64) -> Result<BlockedPackage, BoxError> {
-    let blocks = lock();
-    let held = blocks.held.iter().find(|(held, _)| held.id == id);
-    Ok(held.ok_or(format!("no new package was held back as {id}"))?.0.clone())
-}
-
-/// Returns whether a download was still waiting.
-fn release(id: u64) -> bool {
-    let blocks = lock();
-    let Some((_, wake)) = blocks.held.iter().find(|(held, _)| held.id == id) else {
-        return false;
-    };
-    wake.send_replace(true);
-    wake.receiver_count() > 0
-}
-
-fn push<T>(list: &mut Vec<T>, item: T) {
-    if list.len() == KEPT {
-        list.remove(0);
-    }
-    list.push(item);
-}
-
-fn lock() -> std::sync::MutexGuard<'static, Blocks> {
-    BLOCKS.lock().unwrap_or_else(|e| e.into_inner())
+/// Hands each block over once.
+pub fn take() -> Vec<BlockedPackage> {
+    std::mem::take(&mut *RECENT.lock().unwrap_or_else(|e| e.into_inner()))
 }

core/src/config/mod.rs

@@ -121,7 +121,7 @@ fn merge(base: &mut Map<String, Value>, top: Map<String, Value>) {
 }
 
 /// Adds an `allow` entry to the file, leaving the rest of it as written.
-pub fn allow(path: &Path, eco: &str, name: &str, version: &str) -> std::io::Result<()> {
+pub fn allow(path: &Path, eco: &str, name: &str, version: Option<&str>) -> std::io::Result<()> {
     let invalid = |e: String| Error::new(ErrorKind::InvalidData, format!("{}: {e}", path.display()));
     let mut config = match std::fs::read_to_string(path) {
         Ok(text) => serde_json::from_str(&text).map_err(|e| invalid(e.to_string()))?,

core/src/firewall.rs

@@ -1,4 +1,4 @@
-use crate::config::{AllowedPackage, FirewallConfig};
+use crate::config::FirewallConfig;
 use crate::policies::filters::age::Age;
 use crate::policies::filters::denylist::Denylist;
 use crate::policies::filters::osv::Osv;
@@ -6,16 +6,12 @@ use crate::policies::filters::Filter;
 use crate::policies::registries::*;
 use regex::Regex;
 use std::collections::HashMap;
-use std::sync::Mutex;
-use std::time::Instant;
 
 pub struct Firewall {
     pub config: FirewallConfig,
     registries: Vec<&'static Registry>,
     patterns: HashMap<&'static str, Vec<Regex>>,
     filters: Vec<Box<dyn Filter>>,
-    /// Each lift expires at its time, or lasts until the firewall stops. Never saved.
-    age_lifted: Mutex<Vec<(String, AllowedPackage, Option<Instant>)>>,
 }
 
 impl Default for Firewall {
@@ -38,7 +34,7 @@ impl Firewall {
         if config.min_age_hours > 0 {
             filters.push(Box::new(Age::new(config.min_age_hours)));
         }
-        Firewall { config, registries, patterns, filters, age_lifted: Mutex::default() }
+        Firewall { config, registries, patterns, filters }
     }
 
     pub fn match_on<'a>(
@@ -76,19 +72,6 @@ impl Firewall {
     pub fn filters(&self) -> &[Box<dyn Filter>] {
         &self.filters
     }
-
-    pub fn lift_age_check(&self, eco: &str, package: AllowedPackage, until: Option<Instant>) {
-        let mut lifted = self.age_lifted.lock().unwrap_or_else(|e| e.into_inner());
-        lifted.retain(|(_, _, until)| until.is_none_or(|until| until > Instant::now()));
-        lifted.push((eco.to_owned(), package, until));
-    }
-
-    pub fn age_check_lifted(&self, eco: &str, matches: impl Fn(&AllowedPackage) -> bool) -> bool {
-        let lifted = self.age_lifted.lock().unwrap_or_else(|e| e.into_inner());
-        lifted.iter().any(|(e, package, until)| {
-            e == eco && until.is_none_or(|until| until > Instant::now()) && matches(package)
-        })
-    }
 }
 
 /// The built-ins, then a copy of one per mirror. Leaked, as a `Registry` is `'static` everywhere.

core/src/os/macos/mod.rs

@@ -4,7 +4,7 @@ mod uninstall;
 
 pub use uninstall::uninstall;
 
-use crate::config::FirewallConfig;
+use crate::config::{self, FirewallConfig};
 use crate::{blocks, mitm, telemetry};
 use crate::Firewall;
 use rama::bytes::Bytes;
@@ -22,6 +22,7 @@ use rama::net::apple::networkextension::{transparent_proxy_ffi, NwTcpStream, Tcp
 use rama::rt::Executor;
 use rama::telemetry::tracing::apple::oslog::{OsLogLayer, Privacy};
 use rama::{Layer, Service};
+use serde::Deserialize;
 use std::convert::Infallible;
 use std::path::PathBuf;
 use std::sync::Arc;
@@ -39,7 +40,6 @@ const CONFIG_FILE: &str = "/Library/Application Support/Firewall/config.json";
 struct Handler {
     ca: Arc<mitm::CertificateAuthority>,
     hosts: Vec<&'static str>,
-    firewall: Arc<Firewall>,
     service: mitm::MitmService,
 }
 
@@ -59,7 +59,12 @@ impl TransparentProxyHandler for Handler {
         let message = String::from_utf8_lossy(&message).into_owned();
         Some(Bytes::from(match message.as_str() {
             "ca" => self.ca.pem.clone(),
-            other => blocks::answer(&self.firewall, CONFIG_FILE.as_ref(), other),
+            "blocks" => serde_json::to_string(&blocks::take()).expect("blocks serialize"),
+            other => match other.strip_prefix("allow ").map(allow) {
+                Some(Ok(())) => "ok".to_owned(),
+                Some(Err(error)) => format!("error: {error}"),
+                None => format!("error: unknown message {other}"),
+            },
         }))
     }
 
@@ -114,8 +119,22 @@ fn handler(exec: Executor) -> Result<Handler, BoxError> {
     let signer: mitm::CaSigner = Arc::new(key);
     let ca = install::certificate_authority(&hosts, &*signer);
     let ca = Arc::new(ca.inspect_err(|_| telemetry::error("ca"))?);
-    let service = mitm::mitm_service(firewall.clone(), &ca, signer, None, exec);
-    Ok(Handler { ca, hosts, firewall, service })
+    let service = mitm::mitm_service(firewall, &ca, signer, None, exec);
+    Ok(Handler { ca, hosts, service })
+}
+
+#[derive(Deserialize)]
+struct AllowRequest {
+    eco: String,
+    name: String,
+    version: Option<String>,
+}
+
+/// Takes effect when the provider restarts, which rebuilds it from the config.
+fn allow(request: &str) -> Result<(), BoxError> {
+    let request: AllowRequest = serde_json::from_str(request)?;
+    config::allow(CONFIG_FILE.as_ref(), &request.eco, &request.name, request.version.as_deref())?;
+    Ok(())
 }
 
 /// stderr is invisible in a system extension, so events go to the unified log:

core/src/os/windows/mod.rs

@@ -2,6 +2,7 @@
 //! LocalSystem service screens it as the macOS extension does.
 
 mod ca;
+mod pipe;
 mod service;
 mod tpm;
 mod tray;

core/src/os/windows/pipe.rs

@@ -0,0 +1,58 @@
+//! How the tray asks the service what it blocked, as the macOS app messages its extension.
+
+use super::security_descriptor;
+use crate::blocks;
+use rama::error::BoxError;
+use std::time::Duration;
+use tokio::io::{AsyncBufReadExt, AsyncReadExt, AsyncWriteExt, BufReader};
+use tokio::net::windows::named_pipe::{NamedPipeServer, ServerOptions};
+use windows::Win32::Security::SECURITY_ATTRIBUTES;
+
+pub(super) const PIPE: &str = r"\\.\pipe\StrixFirewall";
+/// Signed-in users can connect, as the tray runs as them.
+const PIPE_ACL: &str = "D:P(A;;GA;;;SY)(A;;GA;;;BA)(A;;GRGW;;;IU)";
+
+pub(super) async fn serve() -> Result<(), BoxError> {
+    let mut server = create(true)?;
+    loop {
+        server.connect().await?;
+        let client = std::mem::replace(&mut server, create(false)?);
+        tokio::spawn(async move {
+            if let Err(error) = answer(client).await {
+                tracing::debug!(%error, "could not answer the tray");
+            }
+        });
+    }
+}
+
+fn create(first: bool) -> Result<NamedPipeServer, BoxError> {
+    let acl = security_descriptor(PIPE_ACL)?;
+    let mut attributes = SECURITY_ATTRIBUTES {
+        nLength: size_of::<SECURITY_ATTRIBUTES>() as u32,
+        lpSecurityDescriptor: acl.0,
+        bInheritHandle: false.into(),
+    };
+    let attributes = (&raw mut attributes).cast();
+    let mut options = ServerOptions::new();
+    // Fails if anyone else made the pipe first.
+    options.first_pipe_instance(first);
+    Ok(unsafe { options.create_with_security_attributes_raw(PIPE, attributes)? })
+}
+
+/// A line each way.
+async fn answer(client: NamedPipeServer) -> Result<(), BoxError> {
+    let mut client = BufReader::new(client);
+    let mut request = String::new();
+    (&mut client)
+        .take(64 * 1024)
+        .read_line(&mut request)
+        .await?;
+    let reply = match request.trim_end() {
+        "blocks" => serde_json::to_string(&blocks::take())?,
+        other => format!("error: unknown request {other}"),
+    };
+    client.write_all(format!("{reply}\n").as_bytes()).await?;
+    // Closing before the tray hangs up could discard the reply.
+    let _ = tokio::time::timeout(Duration::from_secs(5), client.read(&mut [0])).await;
+    Ok(())
+}

core/src/os/windows/service.rs

@@ -1,6 +1,8 @@
 use super::ca::{load_or_create_ca, secure_data_dir};
 use super::tpm::CaKey;
-use super::{config_file, loopback_addresses, write_hosts_entries, CRL_ADDRESS, SERVICE_NAME};
+use super::{
+    config_file, loopback_addresses, pipe, write_hosts_entries, CRL_ADDRESS, SERVICE_NAME,
+};
 use crate::config::FirewallConfig;
 use crate::http::{reply, text};
 use crate::{mitm, telemetry, Firewall};
@@ -153,6 +155,12 @@ async fn start_screening(status: &ServiceStatusHandle) -> Result<Vec<&'static st
     let crl = HttpServer::auto(exec.clone()).service(crl);
     tokio::spawn(listen_on(CRL_ADDRESS, 80, &exec)?.serve(crl));
 
+    tokio::spawn(async {
+        if let Err(error) = pipe::serve().await {
+            tracing::error!(%error, "the tray cannot reach the service");
+        }
+    });
+
     let service = mitm::mitm_service(firewall, &ca, signer, Some(crl_url), exec.clone());
     for (address, host) in loopback_addresses(&hosts) {
         for port in [80, 443] {

core/src/os/windows/tray.rs

@@ -1,17 +1,21 @@
 //! The notification-area icon, started at sign-in as the menu bar app is on macOS.
 
+use super::pipe::PIPE;
 use super::*;
-use muda::{Menu, MenuEvent, MenuItem, PredefinedMenuItem};
-use std::io::Cursor;
+use muda::{Menu, MenuEvent, MenuItem, PredefinedMenuItem, Submenu};
+use serde::Deserialize;
+use std::io::{BufRead, BufReader, Cursor, Write};
+use std::os::windows::io::AsRawHandle;
 use std::time::Duration;
 use tray_icon::{Icon, MouseButtonState, TrayIcon, TrayIconBuilder, TrayIconEvent};
 use windows::core::{w, PCWSTR};
 use windows::Win32::Foundation::*;
+use windows::Win32::System::Pipes::GetNamedPipeServerProcessId;
 use windows::Win32::System::Threading::CreateMutexW;
 use windows::Win32::UI::Shell::*;
 use windows::Win32::UI::WindowsAndMessaging::*;
 use windows_registry::CURRENT_USER;
-use windows_service::service::{Service, ServiceAccess, ServiceState};
+use windows_service::service::{Service, ServiceAccess, ServiceState, ServiceStatus};
 use windows_service::service_manager::{ServiceManager, ServiceManagerAccess};
 
 const MENU_PAUSE: &str = "pause";
@@ -19,6 +23,9 @@ const MENU_RESTART: &str = "restart";
 const MENU_LOG: &str = "log";
 const MENU_QUIT: &str = "quit";
 const LOGO: &[u8] = include_bytes!("tray.png");
+/// Where blocked packages are listed, below Open logs.
+const BLOCKED_AT: usize = 5;
+const BLOCKED_KEPT: usize = 10;
 
 /// Runs until Quit, once per session.
 pub fn run() -> Result<(), BoxError> {
@@ -29,6 +36,7 @@ pub fn run() -> Result<(), BoxError> {
     }
     let status = MenuItem::new("", false, None);
     let pause = MenuItem::with_id(MENU_PAUSE, "", false, None);
+    let blocked_separator = PredefinedMenuItem::separator();
     let menu = Menu::with_items(&[
         &status,
         &PredefinedMenuItem::separator(),
@@ -39,7 +47,9 @@ pub fn run() -> Result<(), BoxError> {
         &MenuItem::with_id(MENU_QUIT, "Quit", true, None),
     ])?;
     let (logo, logo_size) = logo_mask()?;
-    let icon = TrayIconBuilder::new().with_menu(Box::new(menu)).build()?;
+    let icon = TrayIconBuilder::new()
+        .with_menu(Box::new(menu.clone()))
+        .build()?;
     let window = HWND(icon.window_handle());
     let mut tray = Tray {
         icon,
@@ -49,6 +59,9 @@ pub fn run() -> Result<(), BoxError> {
         status,
         pause,
         state: None,
+        menu,
+        blocked_separator,
+        blocked: Vec::new(),
     };
     tray.update();
     unsafe { SetTimer(None, 0, 2000, None) };
@@ -62,6 +75,7 @@ pub fn run() -> Result<(), BoxError> {
         // Ours, not the icon window's own hover timer.
         if message.message == WM_TIMER && message.hwnd.is_invalid() {
             tray.update();
+            tray.collect_blocks();
         }
         while let Ok(event) = TrayIconEvent::receiver().try_recv() {
             // The menu opens on release, so this keeps it current.
@@ -94,11 +108,39 @@ struct Tray {
     pause: MenuItem,
     /// As the menu last showed it.
     state: Option<ServiceState>,
+    menu: Menu,
+    blocked_separator: PredefinedMenuItem,
+    /// The most recent, as the menu lists them.
+    blocked: Vec<BlockedPackage>,
+}
+
+#[derive(Clone, PartialEq, Deserialize)]
+struct BlockedPackage {
+    eco: String,
+    name: String,
+    version: Option<String>,
+    filter: String,
+    reason: String,
+}
+
+impl BlockedPackage {
+    fn label(&self) -> String {
+        match &self.version {
+            Some(version) => format!("{} {version} ({})", self.name, self.eco),
+            None => format!("{} ({})", self.name, self.eco),
+        }
+    }
+
+    /// The denylist and OSV only flag packages known to be malicious; the age check only holds
+    /// back new ones.
+    fn malicious(&self) -> bool {
+        self.filter != "age"
+    }
 }
 
 impl Tray {
     fn update(&mut self) {
-        self.state = service_state();
+        self.state = service_status().map(|status| status.current_state);
         let screening = self.state == Some(ServiceState::Running);
         let light = light_taskbar();
         if self.drawn != Some((light, screening)) {
@@ -117,6 +159,58 @@ impl Tray {
         self.pause.set_enabled(self.state.is_some());
     }
 
+    /// The service hands each block over once, so whichever tray asks first shows it.
+    fn collect_blocks(&mut self) {
+        if self.state != Some(ServiceState::Running) {
+            return;
+        }
+        let Ok(reply) = ask_service("blocks") else {
+            return;
+        };
+        let Ok(packages) = serde_json::from_str::<Vec<BlockedPackage>>(&reply) else {
+            return;
+        };
+        let mut new = Vec::new();
+        for package in packages {
+            if !self.blocked.contains(&package) {
+                self.blocked.push(package.clone());
+                new.push(package);
+            }
+        }
+        if new.is_empty() {
+            return;
+        }
+        let excess = self.blocked.len().saturating_sub(BLOCKED_KEPT);
+        self.blocked.drain(..excess);
+        self.list_blocked();
+        // Off the UI thread, so the menu keeps working while they are open.
+        std::thread::spawn(move || new.iter().for_each(alert));
+    }
+
+    fn list_blocked(&self) {
+        while self.menu.items().len() > BLOCKED_AT + 2 {
+            self.menu.remove_at(BLOCKED_AT);
+        }
+        let _ = self.menu.insert(&self.blocked_separator, BLOCKED_AT);
+        for (i, package) in self.blocked.iter().enumerate() {
+            let verb = if package.malicious() {
+                "Blocked"
+            } else {
+                "Held back"
+            };
+            let reason = if package.malicious() {
+                format!("Malicious: {}", package.reason)
+            } else {
+                package.reason.clone()
+            };
+            let reason = MenuItem::new(reason, false, None);
+            let label = format!("{verb} {}", package.label());
+            if let Ok(item) = Submenu::with_items(label, true, &[&reason]) {
+                let _ = self.menu.insert(&item, BLOCKED_AT + 1 + i);
+            }
+        }
+    }
+
     fn on_menu(&self, id: &str) {
         let state = self.state;
         let screening = state == Some(ServiceState::Running);
@@ -143,6 +237,39 @@ impl Tray {
     }
 }
 
+fn alert(package: &BlockedPackage) {
+    let text = format!("{} {}.", package.label(), package.reason);
+    let (title, text, style) = if package.malicious() {
+        let title = format!("Blocked malware: {}", package.label());
+        let text = text
+            + "\n\nIt was not installed. Don't install it from another source. If you didn't expect this "
+            + "package, a dependency may be compromised; tell your security team.";
+        (title, text, MB_ICONERROR)
+    } else {
+        ("Held back a new package".to_owned(), text, MB_ICONINFORMATION)
+    };
+    let (title, text) = (HSTRING::from(title), HSTRING::from(text));
+    unsafe { MessageBoxW(None, &text, &title, style | MB_SETFOREGROUND) };
+}
+
+/// One request per connection, as the service answers.
+fn ask_service(request: &str) -> Result<String, BoxError> {
+    let mut pipe = std::fs::OpenOptions::new()
+        .read(true)
+        .write(true)
+        .open(PIPE)?;
+    // Any program can create the pipe if it gets there before the service.
+    let mut server = 0;
+    unsafe { GetNamedPipeServerProcessId(HANDLE(pipe.as_raw_handle()), &mut server)? };
+    if service_status().and_then(|status| status.process_id) != Some(server) {
+        return Err("Another program is posing as the firewall service.".into());
+    }
+    pipe.write_all(format!("{request}\n").as_bytes())?;
+    let mut reply = String::new();
+    BufReader::new(pipe).read_line(&mut reply)?;
+    Ok(reply.trim_end().to_owned())
+}
+
 fn show_error(error: BoxError) {
     let text = match error.source() {
         Some(source) => format!("{error}: {source}"),
@@ -153,13 +280,13 @@ fn show_error(error: BoxError) {
 }
 
 /// `None` when the service is not installed.
-fn service_state() -> Option<ServiceState> {
+fn service_status() -> Option<ServiceStatus> {
     let manager =
         ServiceManager::local_computer(None::<&str>, ServiceManagerAccess::CONNECT).ok()?;
     let service = manager
         .open_service(SERVICE_NAME, ServiceAccess::QUERY_STATUS)
         .ok()?;
-    Some(service.query_status().ok()?.current_state)
+    service.query_status().ok()
 }
 
 fn light_taskbar() -> bool {
@@ -167,7 +294,8 @@ fn light_taskbar() -> bool {
     let Ok(key) = CURRENT_USER.open(personalize) else {
         return false;
     };
-    key.get_u32("SystemUsesLightTheme").is_ok_and(|light| light == 1)
+    key.get_u32("SystemUsesLightTheme")
+        .is_ok_and(|light| light == 1)
 }
 
 fn status_text(state: Option<ServiceState>) -> &'static str {

core/src/policies/filters/mod.rs

@@ -3,7 +3,6 @@ pub mod denylist;
 pub mod osv;
 
 use super::registries::{Package, Registry};
-use crate::config::AllowedPackage;
 use crate::Firewall;
 use std::future::Future;
 use std::pin::Pin;
@@ -32,11 +31,10 @@ pub async fn consult(
     registry: &'static Registry,
     pkg: &Package,
 ) -> Option<(&'static str, Verdict)> {
-    let lifted = allowed(firewall, registry, pkg)
-        || firewall.age_check_lifted(registry.eco, |entry| matches(registry, pkg, entry));
+    let allowed = allowed(firewall, registry, pkg);
     let mut unsure = None;
     for filter in firewall.filters() {
-        if lifted && filter.name() == "age" {
+        if allowed && filter.name() == "age" {
             continue;
         }
         match filter.check(registry, pkg).await {
@@ -53,15 +51,13 @@ fn allowed(firewall: &Firewall, registry: &Registry, pkg: &Package) -> bool {
     let Some(entries) = firewall.config.allow.get(registry.eco) else {
         return false;
     };
-    entries.iter().any(|entry| matches(registry, pkg, entry))
-}
-
-fn matches(registry: &Registry, pkg: &Package, entry: &AllowedPackage) -> bool {
-    let name_matches = match registry.normalize {
-        Some(normalize) => normalize(&entry.name) == pkg.name,
-        None => entry.name == pkg.name,
-    };
-    // Go writes a leading v that the parsed version drops, and PEP 440 ignores one.
-    let version = entry.version.as_deref().map(|v| v.strip_prefix('v').unwrap_or(v));
-    name_matches && (version.is_none() || version == pkg.version.as_deref())
+    entries.iter().any(|entry| {
+        let name_matches = match registry.normalize {
+            Some(normalize) => normalize(&entry.name) == pkg.name,
+            None => entry.name == pkg.name,
+        };
+        // Go writes a leading v that the parsed version drops, and PEP 440 ignores one.
+        let version = entry.version.as_deref().map(|v| v.strip_prefix('v').unwrap_or(v));
+        name_matches && (version.is_none() || version == pkg.version.as_deref())
+    })
 }

core/src/policies/mod.rs

@@ -70,10 +70,7 @@ pub async fn screen(url: &str, firewall: &Firewall) -> Option<String> {
     info!(eco = registry.eco, pkg = %pkg.label(), %url, "screening");
     match consult(firewall, registry, &pkg).await {
         Some((filter, Verdict::Deny(reason))) => {
-            if crate::blocks::block(registry.eco, &pkg, filter, &reason).await {
-                info!(eco = registry.eco, pkg = %pkg.label(), "allowed while held");
-                return None;
-            }
+            crate::blocks::record(registry.eco, &pkg, filter, &reason);
             Some(format!("{} {reason}", pkg.label()))
         }
         Some((filter, Verdict::Unknown(e))) if !firewall.config.fail_open => {

core/tests/blocks.rs

@@ -1,27 +0,0 @@
-use firewall::blocks::{answer, block};
-use firewall::policies::Package;
-use firewall::Firewall;
-use std::path::Path;
-use std::time::Duration;
-
-#[tokio::test]
-async fn allowing_once_releases_the_held_download() {
-    let firewall = Firewall::default();
-    let config = Path::new("/nonexistent/config.json");
-    let pkg = Package { name: "left-pad".into(), version: Some("1.3.0".into()) };
-    assert!(!block("npm", &pkg, "age", "is new").await, "held while nothing was asking");
-    answer(&firewall, config, "blocks");
-
-    let held = tokio::spawn(async move { block("npm", &pkg, "age", "is new").await });
-    let id = loop {
-        let blocks: serde_json::Value = serde_json::from_str(&answer(&firewall, config, "blocks")).unwrap();
-        if let Some(id) = blocks[0]["id"].as_u64() {
-            break id;
-        }
-        tokio::time::sleep(Duration::from_millis(10)).await;
-    };
-    assert_eq!(answer(&firewall, config, &format!("allow-once {id}")), "ok");
-    assert!(held.await.unwrap(), "the waiting download goes through");
-    assert!(firewall.age_check_lifted("npm", |p| p.name == "left-pad"), "and the rest of the install");
-    assert!(!block("npm", &Package { name: "evil".into(), version: None }, "denylist", "is malware").await);
-}

core/tests/config.rs

@@ -1,4 +1,4 @@
-use firewall::config::{path, AllowedPackage};
+use firewall::config::path;
 use firewall::policies::filters::consult;
 use firewall::policies::{screen, Package};
 use firewall::{Firewall, FirewallConfig};
@@ -95,23 +95,12 @@ async fn failing_closed_blocks_what_could_not_be_checked() {
     assert!(blocked.contains("could not be checked"), "{blocked:?}");
 }
 
-#[tokio::test]
-async fn lifting_the_age_check_still_checks_for_malware() {
-    let config = r#"{"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()) };
-    firewall.lift_age_check("go", AllowedPackage { name: pkg.name.clone(), version: None }, None);
-    let (filter, _) = consult(&firewall, registry, &pkg).await.expect("the denylist still runs");
-    assert_eq!(filter, "denylist");
-}
-
 #[test]
 fn allowing_keeps_the_rest_of_the_file() {
     let path = std::env::temp_dir().join(format!("firewall-allow-{}.json", std::process::id()));
     std::fs::write(&path, r#"{"fail_open": false}"#).expect("write");
     for _ in 0..2 {
-        firewall::config::allow(&path, "npm", "left-pad", "1.3.0").expect("allow");
+        firewall::config::allow(&path, "npm", "left-pad", Some("1.3.0")).expect("allow");
     }
     let text = std::fs::read_to_string(&path).expect("read");
     std::fs::remove_file(&path).ok();