Confine restricted engines before launch and preserve the reader recovery baseline

restricted-execution/sandbox.nix

@@ -0,0 +1,30 @@
+{
+  pkgs,
+  runtime,
+  executable,
+}:
+let
+  closure = pkgs.closureInfo { rootPaths = [ runtime ]; };
+  filter =
+    pkgs.runCommand "quixos-restricted-seccomp"
+      {
+        nativeBuildInputs = [
+          pkgs.stdenv.cc
+          pkgs.pkg-config
+        ];
+        buildInputs = [ pkgs.libseccomp ];
+      }
+      ''
+        $CC -O2 -Wall -Wextra -Werror ${./seccomp.c} $(pkg-config --cflags --libs libseccomp) -o filter
+        ./filter > "$out"
+      '';
+in
+pkgs.runCommand "quixos-restricted-sandbox" { nativeBuildInputs = [ pkgs.stdenv.cc ]; } ''
+  mkdir -p "$out/bin"
+  $CC -O2 -Wall -Wextra -Werror ${./sandbox.c} \
+    -DSANDBOX_BWRAP='"${pkgs.bubblewrap}/bin/bwrap"' \
+    -DSANDBOX_EXECUTABLE='"${executable}"' \
+    -DSANDBOX_FILTER='"${filter}"' \
+    -DSANDBOX_CLOSURE='"${closure}/store-paths"' \
+    -o "$out/bin/quixos-restricted-sandbox"
+''