feat: add landlock based access restriction functionality

Cargo.toml

@@ -12,7 +12,12 @@ crate-type = [
 ]
 
 [dependencies]
+log = "0.4.18"
 pyo3 = "0.18.3"
+pyo3-log = "0.8.1"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+landlock = "0.2.0"
 
 [dev-dependencies]
 approx = "0.5.0"

src/lib.rs

@@ -1,11 +1,15 @@
 pub mod math_tools;
+pub mod sandbox;
 
 use pyo3::prelude::*;
 
 /// Performance-critical functionality
 #[pymodule]
 fn _native(py: Python, m: &PyModule) -> PyResult<()> {
     math_tools::init_module(py, m)?;
+    sandbox::init_module(py, m)?;
+
+    pyo3_log::init();
 
     Ok(())
 }

src/sandbox.rs

@@ -0,0 +1,120 @@
+#[cfg(target_os = "linux")]
+use landlock::{
+    path_beneath_rules, Access, AccessFs, Ruleset, RulesetAttr, RulesetCreatedAttr, ABI,
+};
+use pyo3::{create_exception, exceptions::PyException, prelude::*, types::PyTuple};
+
+use log;
+
+#[derive(Clone, Debug)]
+pub enum FSAccess {
+    Read(String),
+    ReadWrite(String),
+}
+
+#[cfg(target_os = "linux")]
+impl FSAccess {
+    fn read(&self) -> Option<&str> {
+        if let Self::Read(path) = self {
+            Some(path)
+        } else {
+            None
+        }
+    }
+    fn read_write(&self) -> Option<&str> {
+        if let Self::ReadWrite(path) = self {
+            Some(path)
+        } else {
+            None
+        }
+    }
+}
+
+pub fn restrict_access(access_rules: &[FSAccess]) -> Result<(), Box<dyn std::error::Error>> {
+    #[cfg(target_os = "linux")]
+    {
+        let abi = ABI::V1;
+
+        let read_only: Vec<&str> = access_rules.iter().filter_map(FSAccess::read).collect();
+
+        let read_write: Vec<&str> = access_rules
+            .iter()
+            .filter_map(FSAccess::read_write)
+            .collect();
+
+        let status = Ruleset::new()
+            .handle_access(AccessFs::from_all(abi))?
+            .create()?
+            .add_rules(path_beneath_rules(read_only, AccessFs::from_read(abi)))?
+            .add_rules(path_beneath_rules(read_write, AccessFs::from_all(abi)))?
+            .restrict_self()?;
+
+        log::info!(
+            "Activated FS access restrictions; rules={:?}, status={:?}",
+            access_rules,
+            status.ruleset
+        );
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    log::warn!("Sandboxing FS access is unavailable on this system");
+
+    Ok(())
+}
+
+/// Enforces access restrictions
+#[pyfunction(name = "restrict_access", signature=(*rules))]
+fn py_restrict_access(_py: Python, rules: &PyTuple) -> PyResult<()> {
+    restrict_access(
+        &rules
+            .iter()
+            .map(|r| Ok(r.extract::<PyFSAccess>()?.access))
+            .collect::<PyResult<Vec<_>>>()?,
+    )
+    .map_err(|err| SandboxError::new_err(err.to_string()))
+}
+
+create_exception!(unblob_native.sandbox, SandboxError, PyException);
+
+#[pyclass(name = "FSAccess", module = "unblob_native.sandbox")]
+#[derive(Clone)]
+struct PyFSAccess {
+    access: FSAccess,
+}
+
+impl PyFSAccess {
+    fn new(access: FSAccess) -> Self {
+        Self { access }
+    }
+}
+
+#[pymethods]
+impl PyFSAccess {
+    #[staticmethod]
+    fn read(dir: String) -> Self {
+        Self::new(FSAccess::Read(dir))
+    }
+
+    #[staticmethod]
+    fn read_write(dir: String) -> Self {
+        Self::new(FSAccess::ReadWrite(dir))
+    }
+}
+
+pub fn init_module(py: Python, root_module: &PyModule) -> PyResult<()> {
+    let module = PyModule::new(py, "sandbox")?;
+    module.add_function(wrap_pyfunction!(py_restrict_access, module)?)?;
+    module.add_class::<PyFSAccess>()?;
+
+    root_module.add_submodule(module)?;
+
+    let sys = PyModule::import(py, "sys")?;
+    let modules = sys.getattr("modules")?;
+    modules.call_method(
+        "__setitem__",
+        ("unblob_native.sandbox".to_string(), module),
+        None,
+    )?;
+
+    Ok(())
+}