Unverified Commit b29c6f5a authored by Jörg Thalheim's avatar Jörg Thalheim Committed by GitHub
Browse files

stage-2-init: fix false positives for RO Nix store mounts (#375257)

parents b97dde9a 2f3a80c9

nixos/modules/system/boot/stage-2-init.sh

+2 −1
Original line number Diff line number Diff line
@@ -69,7 +69,8 @@ fi 
chown -f 0:30000 /nix/store

chmod -f 1775 /nix/store

if [ -n "@readOnlyNixStore@" ]; then

    if ! [[ "$(findmnt --noheadings --output OPTIONS /nix/store)" =~ ro(,|$) ]]; then

    # #375257: Ensure that we pick the "top" (i.e. last) mount so we don't get a false positive for a lower mount.

    if ! [[ "$(findmnt --direction backward --first-only --noheadings --output OPTIONS /nix/store)" =~ (^|,)ro(,|$) ]]; then

        if [ -z "$container" ]; then

            mount --bind /nix/store /nix/store

        else

nixos/tests/all-tests.nix

+1 −0
Original line number Diff line number Diff line
@@ -165,6 +165,7 @@ in { 
  boot = handleTestOn ["x86_64-linux" "aarch64-linux"] ./boot.nix {};

  bootspec = handleTestOn ["x86_64-linux"] ./bootspec.nix {};

  boot-stage1 = handleTest ./boot-stage1.nix {};

  boot-stage2 = handleTest ./boot-stage2.nix {};

  borgbackup = handleTest ./borgbackup.nix {};

  borgmatic = handleTest ./borgmatic.nix {};

  botamusique = handleTest ./botamusique.nix {};

nixos/tests/boot-stage2.nix

0 → 100644
+73 −0
Original line number Diff line number Diff line 
import ./make-test-python.nix (

  { pkgs, ... }:

  {

    name = "boot-stage2";



    nodes.machine =

      {

        config,

        pkgs,

        lib,

        ...

      }:

      {

        virtualisation = {

          emptyDiskImages = [ 256 ];



          # Mount an ext4 as the upper layer of the Nix store.

          fileSystems = {

            "/nix/store" = lib.mkForce {

              device = "/dev/vdb"; # the above disk image

              fsType = "ext4";



              # data=journal always displays after errors=remount-ro; this is only needed because of the overlay

              # and #375257 will trigger with `errors=remount-ro` on a non-overlaid store:

              # see ordering in https://github.com/torvalds/linux/blob/v6.12/fs/ext4/super.c#L2974

              options = [

                "defaults"

                "errors=remount-ro"

                "data=journal"

              ];

            };

          };

        };



        boot = {

          initrd = {

            # Format the upper Nix store.

            postDeviceCommands = ''

              ${pkgs.e2fsprogs}/bin/mkfs.ext4 /dev/vdb

            '';



            # Overlay the RO store onto it.

            # Note that bug #375257 can be triggered without an overlay,

            # using the errors=remount-ro option (or similar) or with an overlay where any of the

            # paths ends in 'ro'. The offending mountpoint also has to be the last (top) one

            # if an option ending in 'ro' is the last in the list, so test both cases here.

            postMountCommands = ''

              mkdir -p /mnt-root/nix/store/ro /mnt-root/nix/store/rw /mnt-root/nix/store/work

              mount --bind /mnt-root/nix/.ro-store /mnt-root/nix/store/ro

              mount -t overlay overlay \

                -o lowerdir=/mnt-root/nix/store/ro,upperdir=/mnt-root/nix/store/rw,workdir=/mnt-root/nix/store/work \

                /mnt-root/nix/store

            '';



            kernelModules = [ "overlay" ];

          };



          postBootCommands = ''

            touch /etc/post-boot-ran

            mount

          '';

        };

      };



    testScript = ''

      machine.wait_for_unit("multi-user.target")

      machine.succeed("test /etc/post-boot-ran")

      machine.fail("touch /nix/store/should-not-work");

    '';



    meta.maintainers = with pkgs.lib.maintainers; [ numinit ];

  }

)