Hold a held-back download open so allowing it lets it through

core/Cargo.toml

@@ -90,6 +90,10 @@ 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 = []
@@ -125,7 +129,7 @@ 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_Pipes", "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_Threading", "Win32_UI_Shell", "Win32_UI_WindowsAndMessaging"] }
 windows-registry = "0.6.1"
 windows-service = "0.8.0"
 

core/src/blocks.rs

@@ -1,14 +1,25 @@
+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;
 
-/// Bounded, so blocks pile up harmlessly while nothing collects them.
+/// So blocks can't pile up while no app 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);
 
-static RECENT: Mutex<Vec<BlockedPackage>> = Mutex::new(Vec::new());
-
-#[derive(Serialize)]
+#[derive(Clone, Serialize)]
 pub struct BlockedPackage {
+    pub id: u64,
     pub eco: &'static str,
     pub name: String,
     pub version: Option<String>,
@@ -16,21 +27,125 @@ pub struct BlockedPackage {
     pub reason: String,
 }
 
-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);
+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");
     }
-    recent.push(BlockedPackage {
+    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,
         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)
 }
 
-/// Hands each block over once.
-pub fn take() -> Vec<BlockedPackage> {
-    std::mem::take(&mut *RECENT.lock().unwrap_or_else(|e| e.into_inner()))
+/// 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())
 }

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: Option<&str>) -> std::io::Result<()> {
+pub fn allow(path: &Path, eco: &str, name: &str, version: &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::FirewallConfig;
+use crate::config::{AllowedPackage, FirewallConfig};
 use crate::policies::filters::age::Age;
 use crate::policies::filters::denylist::Denylist;
 use crate::policies::filters::osv::Osv;
@@ -6,12 +6,16 @@ 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 {
@@ -34,7 +38,7 @@ impl Firewall {
         if config.min_age_hours > 0 {
             filters.push(Box::new(Age::new(config.min_age_hours)));
         }
-        Firewall { config, registries, patterns, filters }
+        Firewall { config, registries, patterns, filters, age_lifted: Mutex::default() }
     }
 
     pub fn match_on<'a>(
@@ -72,6 +76,19 @@ 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::{self, FirewallConfig};
+use crate::config::FirewallConfig;
 use crate::{blocks, mitm, telemetry};
 use crate::Firewall;
 use rama::bytes::Bytes;
@@ -22,7 +22,6 @@ 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;
@@ -40,6 +39,7 @@ 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,
 }
 
@@ -59,12 +59,7 @@ 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(),
-            "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}"),
-            },
+            other => blocks::answer(&self.firewall, CONFIG_FILE.as_ref(), other),
         }))
     }
 
@@ -119,22 +114,8 @@ 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, &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(())
+    let service = mitm::mitm_service(firewall.clone(), &ca, signer, None, exec);
+    Ok(Handler { ca, hosts, firewall, service })
 }
 
 /// stderr is invisible in a system extension, so events go to the unified log:

core/src/os/windows/mod.rs

@@ -2,7 +2,6 @@
 //! 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

@@ -1,58 +0,0 @@
-//! 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

@@ -1,8 +1,6 @@
 use super::ca::{load_or_create_ca, secure_data_dir};
 use super::tpm::CaKey;
-use super::{
-    config_file, loopback_addresses, pipe, write_hosts_entries, CRL_ADDRESS, SERVICE_NAME,
-};
+use super::{config_file, loopback_addresses, write_hosts_entries, CRL_ADDRESS, SERVICE_NAME};
 use crate::config::FirewallConfig;
 use crate::http::{reply, text};
 use crate::{mitm, telemetry, Firewall};
@@ -155,12 +153,6 @@ 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

@@ -1,21 +1,17 @@
 //! 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, Submenu};
-use serde::Deserialize;
-use std::io::{BufRead, BufReader, Cursor, Write};
-use std::os::windows::io::AsRawHandle;
+use muda::{Menu, MenuEvent, MenuItem, PredefinedMenuItem};
+use std::io::Cursor;
 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, ServiceStatus};
+use windows_service::service::{Service, ServiceAccess, ServiceState};
 use windows_service::service_manager::{ServiceManager, ServiceManagerAccess};
 
 const MENU_PAUSE: &str = "pause";
@@ -23,9 +19,6 @@ 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> {
@@ -36,7 +29,6 @@ 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(),
@@ -47,9 +39,7 @@ 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.clone()))
-        .build()?;
+    let icon = TrayIconBuilder::new().with_menu(Box::new(menu)).build()?;
     let window = HWND(icon.window_handle());
     let mut tray = Tray {
         icon,
@@ -59,9 +49,6 @@ pub fn run() -> Result<(), BoxError> {
         status,
         pause,
         state: None,
-        menu,
-        blocked_separator,
-        blocked: Vec::new(),
     };
     tray.update();
     unsafe { SetTimer(None, 0, 2000, None) };
@@ -75,7 +62,6 @@ 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.
@@ -108,39 +94,11 @@ 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_status().map(|status| status.current_state);
+        self.state = service_state();
         let screening = self.state == Some(ServiceState::Running);
         let light = light_taskbar();
         if self.drawn != Some((light, screening)) {
@@ -159,58 +117,6 @@ 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);
@@ -237,39 +143,6 @@ 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}"),
@@ -280,13 +153,13 @@ fn show_error(error: BoxError) {
 }
 
 /// `None` when the service is not installed.
-fn service_status() -> Option<ServiceStatus> {
+fn service_state() -> Option<ServiceState> {
     let manager =
         ServiceManager::local_computer(None::<&str>, ServiceManagerAccess::CONNECT).ok()?;
     let service = manager
         .open_service(SERVICE_NAME, ServiceAccess::QUERY_STATUS)
         .ok()?;
-    service.query_status().ok()
+    Some(service.query_status().ok()?.current_state)
 }
 
 fn light_taskbar() -> bool {
@@ -294,8 +167,7 @@ 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

@@ -3,6 +3,7 @@ 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;
@@ -31,10 +32,11 @@ pub async fn consult(
     registry: &'static Registry,
     pkg: &Package,
 ) -> Option<(&'static str, Verdict)> {
-    let allowed = allowed(firewall, registry, pkg);
+    let lifted = allowed(firewall, registry, pkg)
+        || firewall.age_check_lifted(registry.eco, |entry| matches(registry, pkg, entry));
     let mut unsure = None;
     for filter in firewall.filters() {
-        if allowed && filter.name() == "age" {
+        if lifted && filter.name() == "age" {
             continue;
         }
         match filter.check(registry, pkg).await {
@@ -51,13 +53,15 @@ 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| {
-        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| 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())
 }

core/src/policies/mod.rs

@@ -70,7 +70,10 @@ 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))) => {
-            crate::blocks::record(registry.eco, &pkg, filter, &reason);
+            if crate::blocks::block(registry.eco, &pkg, filter, &reason).await {
+                info!(eco = registry.eco, pkg = %pkg.label(), "allowed while held");
+                return None;
+            }
             Some(format!("{} {reason}", pkg.label()))
         }
         Some((filter, Verdict::Unknown(e))) if !firewall.config.fail_open => {

core/tests/blocks.rs

@@ -0,0 +1,27 @@
+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;
+use firewall::config::{path, AllowedPackage};
 use firewall::policies::filters::consult;
 use firewall::policies::{screen, Package};
 use firewall::{Firewall, FirewallConfig};
@@ -95,12 +95,23 @@ 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", Some("1.3.0")).expect("allow");
+        firewall::config::allow(&path, "npm", "left-pad", "1.3.0").expect("allow");
     }
     let text = std::fs::read_to_string(&path).expect("read");
     std::fs::remove_file(&path).ok();