feat(boot): gatekeeper gates boot (init→UI→gatekeeper→data); keystore disk + virtio-rng discovery; terminal READ_SECRET; storage SET_KEY; PageCount ≤8192, alloc cap gone; device window 0x01D0_0000; test-qemu types passcode over 2 boots

crates/servers/gatekeeper/Cargo.toml

@@ -6,3 +6,14 @@ edition = "2024"
 [dependencies]
 keystore = { workspace = true }
 zeroize = { workspace = true }
+types = { workspace = true }
+libkos = { workspace = true }
+port-block-device = { workspace = true }
+port-entropy = { workspace = true }
+driver-block-virtio = { workspace = true }
+driver-rng-virtio = { workspace = true }
+
+[[bin]]
+name = "gatekeeper"
+test = false
+bench = false

crates/servers/gatekeeper/src/devices.rs

@@ -0,0 +1,55 @@
+//! The flow's ports on real devices: the keystore disk, virtio-rng, and
+//! the terminal.
+
+use libkos::io::print_to;
+use port_block_device::{BlockDevice, SectorId};
+use port_entropy::Entropy;
+use types::bounded::CapSlot;
+
+use crate::flow::{Keystore, MAX_SECRET, Prompt, Secret};
+use keystore::RECORD_SIZE;
+
+/// The record's two copies are its first two sectors.
+pub struct Disk<D: BlockDevice>(pub D);
+
+impl<D: BlockDevice> Keystore for Disk<D> {
+    fn read(&mut self, copy: usize, out: &mut [u8; RECORD_SIZE]) -> bool {
+        self.0.sector_size() == RECORD_SIZE && self.0.read_sector(SectorId::new(copy as u32), out)
+    }
+
+    fn write(&mut self, copy: usize, data: &[u8; RECORD_SIZE]) -> bool {
+        self.0.sector_size() == RECORD_SIZE && self.0.write_sector(SectorId::new(copy as u32), data)
+    }
+}
+
+pub struct Hardware<E: Entropy>(pub E);
+
+impl<E: Entropy> keystore::Random for Hardware<E> {
+    fn fill(&mut self, buf: &mut [u8]) -> bool {
+        self.0.fill(buf)
+    }
+}
+
+pub struct Terminal(pub CapSlot);
+
+impl Prompt for Terminal {
+    fn say(&mut self, text: &str) {
+        print_to(self.0, format_args!("{}", text));
+    }
+
+    fn clear(&mut self) {
+        libkos::terminal::clear(self.0);
+    }
+
+    fn secret(&mut self, question: &str, out: &mut Secret) -> bool {
+        print_to(self.0, format_args!("{}", question));
+        let mut line = Secret::new();
+        let mut buf = [0u8; MAX_SECRET + 1];
+        let n = libkos::terminal::read_secret(self.0, &mut buf);
+        let typed = buf[..n].strip_suffix(b"\n").unwrap_or(&buf[..n]);
+        line.set(typed);
+        buf.fill(0);
+        out.set(line.as_bytes());
+        n > 0
+    }
+}

crates/servers/gatekeeper/src/flow.rs

@@ -57,6 +57,8 @@ impl Drop for Secret {
 /// The owner, on the screen and keyboard.
 pub trait Prompt {
     fn say(&mut self, text: &str);
+    /// Blanks the screen.
+    fn clear(&mut self);
     /// Shows `question` and reads a passcode without showing it; false if
     /// nothing could be read.
     fn secret(&mut self, question: &str, out: &mut Secret) -> bool;
@@ -128,6 +130,8 @@ fn choose(prompt: &mut impl Prompt, question: &str, optional: bool, out: &mut Se
 /// A device never set up (or wiped): the owner chooses a passcode, and
 /// may choose a duress one. Returns the new master key.
 fn setup(ks: &mut impl Keystore, rng: &mut impl Random, prompt: &mut impl Prompt, params: KdfParams, memory: &mut [Block]) -> Result<Key, Failure> {
+    // After a wipe nothing earlier may show: it must look like a new device.
+    prompt.clear();
     prompt.say("This device has no passcode yet. Choose one; it protects everything on it.\n");
     let mut real = Secret::new();
     choose(prompt, "New passcode: ", false, &mut real)?;

crates/servers/gatekeeper/src/lib.rs

@@ -7,8 +7,78 @@
 
 extern crate alloc;
 
+pub mod devices;
 pub mod flow;
 
 #[cfg(test)]
 #[path = "tests/mod.rs"]
 mod tests;
+
+use alloc::vec;
+use keystore::{Block, KdfParams};
+use libkos::syscall::{self, Received};
+use types::bounded::CapSlot;
+use types::gatekeeper::{KEY, UNLOCK, reply};
+
+/// Where init's manifest put them: its own endpoint (devices arrive on
+/// it, then init's calls), then the terminal.
+const EP: CapSlot = CapSlot::const_new(0);
+const TERMINAL: CapSlot = CapSlot::const_new(1);
+
+/// Answers init's next call, if it is `op`, with `words`.
+fn answer(op: usize, words: [usize; 4]) -> bool {
+    loop {
+        match syscall::receive_msg(EP) {
+            Ok(Received::Call { badge: 0, words: [w, ..], .. }) if w == op => {
+                return syscall::reply(words, None).is_ok();
+            }
+            // Anyone else, or anything else: refused.
+            Ok(Received::Call { .. }) => {
+                let _ = syscall::reply([reply::FAILED, 0, 0, 0], None);
+            }
+            Ok(_) => {}
+            Err(_) => return false,
+        }
+    }
+}
+
+pub fn run() -> ! {
+    // Init hands over the keystore disk, then the randomness device.
+    let keystore = libkos::device::receive_device(EP).mmio.and_then(driver_block_virtio::VirtioBlockDevice::new);
+    let random = libkos::device::receive_device(EP).mmio.and_then(driver_rng_virtio::VirtioRng::new);
+    let (Some(keystore), Some(random)) = (keystore, random) else {
+        libkos::println!("gatekeeper: no keystore or no randomness, nothing to unlock with");
+        let _ = answer(UNLOCK, [reply::FAILED, 0, 0, 0]);
+        syscall::exit();
+    };
+    let mut memory = vec![Block::default(); KdfParams::DEFAULT.memory_kib as usize];
+    libkos::println!("gatekeeper: waiting for the owner");
+    let key = flow::run(
+        &mut devices::Disk(keystore),
+        &mut devices::Hardware(random),
+        &mut devices::Terminal(TERMINAL),
+        KdfParams::DEFAULT,
+        &mut memory,
+    );
+    // The guesses' working memory goes before anything else happens.
+    for b in memory.iter_mut() {
+        *b = Block::default();
+    }
+    drop(memory);
+    match key {
+        Ok(key) => {
+            libkos::println!("gatekeeper: unlocked");
+            libkos::terminal::clear(TERMINAL);
+            let word = |i: usize| usize::from_le_bytes(key.0[i * 8..i * 8 + 8].try_into().unwrap_or([0; 8]));
+            if answer(UNLOCK, [reply::OK, 0, 0, 0]) {
+                let _ = answer(KEY, [word(0), word(1), word(2), word(3)]);
+            }
+        }
+        Err(why) => {
+            libkos::println!("gatekeeper: cannot go on: {:?}", why);
+            let _ = answer(UNLOCK, [reply::FAILED, 0, 0, 0]);
+        }
+    }
+    // Its capabilities go with it.
+    syscall::exit()
+}

crates/servers/gatekeeper/src/main.rs

@@ -0,0 +1,11 @@
+#![no_std]
+#![forbid(unsafe_code)]
+#![no_main]
+
+extern crate libkos;
+
+libkos::entry!(main);
+
+fn main() {
+    gatekeeper::run();
+}

crates/servers/gatekeeper/src/tests/mod.rs

@@ -67,18 +67,26 @@ impl Random for Counter {
 /// An owner typing from a script; what was shown is kept.
 struct Owner {
     typing: VecDeque<&'static str>,
+    /// On the screen now.
     shown: String,
+    /// Ever shown, cleared or not.
+    said: String,
 }
 
 impl Owner {
     fn types(lines: &[&'static str]) -> Self {
-        Self { typing: lines.iter().copied().collect(), shown: String::new() }
+        Self { typing: lines.iter().copied().collect(), shown: String::new(), said: String::new() }
     }
 }
 
 impl Prompt for Owner {
     fn say(&mut self, text: &str) {
         self.shown.push_str(text);
+        self.said.push_str(text);
+    }
+    /// What a fresh screen shows: nothing that came before.
+    fn clear(&mut self) {
+        self.shown.clear();
     }
     fn secret(&mut self, question: &str, out: &mut Secret) -> bool {
         self.shown.push_str(question);
@@ -158,7 +166,7 @@ fn too_many_wrong_passcodes_wipe_the_keys_and_the_device_starts_fresh() {
     guesses.extend(["5678", "5678", "", ""]);
     let mut owner = Owner::types(&guesses);
     let new = run_with(&mut dev, &mut owner).unwrap();
-    assert!(owner.shown.contains("One try left"));
+    assert!(owner.said.contains("One try left"));
     assert!(owner.shown.ends_with("This device has no passcode yet. Choose one; it protects everything on it.\nNew passcode: Again: A duress passcode wipes the device when it is entered instead. Leave it empty for none.\nDuress passcode: Again: "));
     assert_ne!(new.0, key, "the old master key is gone");
     let mut old = Owner::types(&["1234"]);
@@ -173,6 +181,7 @@ fn the_duress_passcode_wipes_silently_and_the_device_looks_fresh() {
     let mut owner = Owner::types(&["0000", "4321", "4321", "", ""]);
     let new = run_with(&mut dev, &mut owner).unwrap();
     assert!(!owner.shown.contains("Wrong"), "nothing tells it was a duress passcode");
+    assert!(owner.shown.starts_with("This device has no passcode yet"), "nor is the passcode prompt left showing");
     assert!(owner.shown.contains("no passcode yet"));
     assert_ne!(new.0, key);
 }