feat(apps): permission manager equips apps (manifest+consent+decisions in /system), launches via init w/ file grant; shell unprivileged (/home); install/apps/allow/revoke; revoke stops running app; app-image tool; counter app

crates/tools/app-image/src/main.rs

@@ -0,0 +1,64 @@
+//! Puts apps on a disk image being built (see docs/apps.md), checked by
+//! the same strict parser the permission manager uses:
+//!
+//!   app-image install <root> <manifest.toml> <binary>
+//!       an installed, pre-approved app: /apps/<id>/, its decision granting
+//!       everything it asks for, and /data/<id>/ if that includes storage
+//!   app-image stage <folder> <manifest.toml> <binary>
+//!       an app folder the owner can install later (`install <folder>`)
+
+use manifest::{Capability, Decision, MAX_DECISION_TEXT, Manifest};
+use std::path::Path;
+use std::process::ExitCode;
+use std::{env, fs};
+
+fn read(manifest: &Path) -> Result<(Manifest, String), String> {
+    let text = fs::read_to_string(manifest).map_err(|e| format!("{}: {e}", manifest.display()))?;
+    let m = Manifest::parse(&text).map_err(|e| format!("{}: {e:?}", manifest.display()))?;
+    Ok((m, text))
+}
+
+/// The manifest and the binary (under the name the manifest gives it).
+fn put_app(folder: &Path, m: &Manifest, text: &str, binary: &Path) -> Result<(), String> {
+    fs::create_dir_all(folder).map_err(|e| format!("{}: {e}", folder.display()))?;
+    fs::write(folder.join("manifest.toml"), text).map_err(|e| e.to_string())?;
+    fs::copy(binary, folder.join(m.binary.as_str()))
+        .map_err(|e| format!("{}: {e}", binary.display()))?;
+    Ok(())
+}
+
+fn install(root: &Path, manifest: &Path, binary: &Path) -> Result<(), String> {
+    let (m, text) = read(manifest)?;
+    put_app(&root.join("apps").join(m.id.as_str()), &m, &text, binary)?;
+    // Whoever builds the image approves what its apps ask for.
+    let decision = Decision {
+        granted: m.requested(),
+    };
+    let mut out = [0u8; MAX_DECISION_TEXT];
+    let n = decision.write(&mut out);
+    let decisions = root.join("system/permissions");
+    fs::create_dir_all(&decisions).map_err(|e| e.to_string())?;
+    fs::write(decisions.join(m.id.as_str()), &out[..n]).map_err(|e| e.to_string())?;
+    if decision.granted.contains(Capability::Storage) {
+        fs::create_dir_all(root.join("data").join(m.id.as_str())).map_err(|e| e.to_string())?;
+    }
+    Ok(())
+}
+
+fn main() -> ExitCode {
+    let args: Vec<String> = env::args().skip(1).collect();
+    let done = match args.iter().map(String::as_str).collect::<Vec<_>>().as_slice() {
+        ["install", root, manifest, binary] => install(Path::new(root), Path::new(manifest), Path::new(binary)),
+        ["stage", folder, manifest, binary] => {
+            read(Path::new(manifest)).and_then(|(m, text)| put_app(Path::new(folder), &m, &text, Path::new(binary)))
+        }
+        _ => Err("usage: app-image install <root> <manifest> <binary> | stage <folder> <manifest> <binary>".into()),
+    };
+    match done {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(e) => {
+            eprintln!("app-image: {e}");
+            ExitCode::FAILURE
+        }
+    }
+}