From 9a0f523372cf836662421ef2603bfb93f568f399 Mon Sep 17 00:00:00 2001 From: Will Fancher Date: Tue, 19 Sep 2023 23:39:51 -0400 Subject: [PATCH] systemd-stage-1: Enable backdoor in nixos tests --- .../manual/release-notes/rl-2311.section.md | 2 + nixos/lib/test-driver/test_driver/machine.py | 16 +++++ .../modules/testing/test-instrumentation.nix | 71 ++++++++++++++++--- nixos/tests/systemd-initrd-simple.nix | 12 ++-- 4 files changed, 86 insertions(+), 15 deletions(-) diff --git a/nixos/doc/manual/release-notes/rl-2311.section.md b/nixos/doc/manual/release-notes/rl-2311.section.md index 22bc4c31618e..e33f6b337e2d 100644 --- a/nixos/doc/manual/release-notes/rl-2311.section.md +++ b/nixos/doc/manual/release-notes/rl-2311.section.md @@ -554,3 +554,5 @@ The module update takes care of the new config syntax and the data itself (user - `teleport` has been upgraded from major version 12 to major version 14. Please see upstream [upgrade instructions](https://goteleport.com/docs/management/operations/upgrading/) and release notes for versions [13](https://goteleport.com/docs/changelog/#1300-050823) and [14](https://goteleport.com/docs/changelog/#1400-092023). Note that Teleport does not officially support upgrades across more than one major version at a time. If you're running Teleport server components, it is recommended to first upgrade to an intermediate 13.x version by setting `services.teleport.package = pkgs.teleport_13`. Afterwards, this option can be removed to upgrade to the default version (14). - The Linux kernel module `msr` (see [`msr(4)`](https://man7.org/linux/man-pages/man4/msr.4.html)), which provides an interface to read and write the model-specific registers (MSRs) of an x86 CPU, can now be configured via `hardware.cpu.x86.msr`. + +- There is a new NixOS option when writing NixOS tests `testing.initrdBackdoor`, that enables `backdoor.service` in initrd. Requires `boot.initrd.systemd.enable` to be enabled. Boot will pause in stage 1 at `initrd.target`, and will listen for commands from the `Machine` python interface, just like stage 2 normally does. This enables commands to be sent to test and debug stage 1. Use `machine.switch_root()` to leave stage 1 and proceed to stage 2. diff --git a/nixos/lib/test-driver/test_driver/machine.py b/nixos/lib/test-driver/test_driver/machine.py index 529de41d892a..f430321bb607 100644 --- a/nixos/lib/test-driver/test_driver/machine.py +++ b/nixos/lib/test-driver/test_driver/machine.py @@ -1278,3 +1278,19 @@ class Machine: def run_callbacks(self) -> None: for callback in self.callbacks: callback() + + def switch_root(self) -> None: + """ + Transition from stage 1 to stage 2. This requires the + machine to be configured with `testing.initrdBackdoor = true` + and `boot.initrd.systemd.enable = true`. + """ + self.wait_for_unit("initrd.target") + self.execute( + "systemctl isolate --no-block initrd-switch-root.target 2>/dev/null >/dev/null", + check_return=False, + check_output=False, + ) + self.wait_for_console_text(r"systemd\[1\]:.*Switching root\.") + self.connected = False + self.connect() diff --git a/nixos/modules/testing/test-instrumentation.nix b/nixos/modules/testing/test-instrumentation.nix index 6c4b4f13d04b..abe68dd6eae6 100644 --- a/nixos/modules/testing/test-instrumentation.nix +++ b/nixos/modules/testing/test-instrumentation.nix @@ -6,10 +6,15 @@ with lib; let + cfg = config.testing; + qemu-common = import ../../lib/qemu-common.nix { inherit lib pkgs; }; backdoorService = { - wantedBy = [ "multi-user.target" ]; + wantedBy = [ "sysinit.target" ]; + unitConfig.DefaultDependencies = false; + conflicts = [ "shutdown.target" "initrd-switch-root.target" ]; + before = [ "shutdown.target" "initrd-switch-root.target" ]; requires = [ "dev-hvc0.device" "dev-${qemu-common.qemuSerialDevice}.device" ]; after = [ "dev-hvc0.device" "dev-${qemu-common.qemuSerialDevice}.device" ]; script = @@ -18,7 +23,9 @@ let export HOME=/root export DISPLAY=:0.0 - source /etc/profile + if [[ -e /etc/profile ]]; then + source /etc/profile + fi # Don't use a pager when executing backdoor # actions. Because we use a tty, commands like systemctl @@ -49,9 +56,59 @@ in { + options.testing = { + + initrdBackdoor = lib.mkEnableOption (lib.mdDoc '' + enable backdoor.service in initrd. Requires + boot.initrd.systemd.enable to be enabled. Boot will pause in + stage 1 at initrd.target, and will listen for commands from the + Machine python interface, just like stage 2 normally does. This + enables commands to be sent to test and debug stage 1. Use + machine.switch_root() to leave stage 1 and proceed to stage 2. + ''); + + }; + config = { - systemd.services.backdoor = backdoorService + assertions = [ + { + assertion = cfg.initrdBackdoor -> config.boot.initrd.systemd.enable; + message = '' + testing.initrdBackdoor requires boot.initrd.systemd.enable to be enabled. + ''; + } + ]; + + systemd.services.backdoor = backdoorService; + + boot.initrd.systemd = lib.mkMerge [ + { + contents."/etc/systemd/journald.conf".text = '' + [Journal] + ForwardToConsole=yes + MaxLevelConsole=debug + ''; + + extraConfig = config.systemd.extraConfig; + } + + (lib.mkIf cfg.initrdBackdoor { + # Implemented in machine.switch_root(). Suppress the unit by + # making it a noop without removing it, which would break + # initrd-parse-etc.service + services.initrd-cleanup.serviceConfig.ExecStart = [ + # Reset + "" + # noop + "/bin/true" + ]; + + services.backdoor = backdoorService; + + contents."/usr/bin/env".source = "${pkgs.coreutils}/bin/env"; + }) + ]; # Prevent agetty from being instantiated on the serial device, since it # interferes with the backdoor (writes to it will randomly fail @@ -107,12 +164,6 @@ in MaxLevelConsole=debug ''; - boot.initrd.systemd.contents."/etc/systemd/journald.conf".text = '' - [Journal] - ForwardToConsole=yes - MaxLevelConsole=debug - ''; - systemd.extraConfig = '' # Don't clobber the console with duplicate systemd messages. ShowStatus=no @@ -126,8 +177,6 @@ in DefaultDeviceTimeoutSec=300 ''; - boot.initrd.systemd.extraConfig = config.systemd.extraConfig; - boot.consoleLogLevel = 7; # Prevent tests from accessing the Internet. diff --git a/nixos/tests/systemd-initrd-simple.nix b/nixos/tests/systemd-initrd-simple.nix index a6a22e9d48e0..2b7283a82193 100644 --- a/nixos/tests/systemd-initrd-simple.nix +++ b/nixos/tests/systemd-initrd-simple.nix @@ -2,16 +2,19 @@ import ./make-test-python.nix ({ lib, pkgs, ... }: { name = "systemd-initrd-simple"; nodes.machine = { pkgs, ... }: { - boot.initrd.systemd = { - enable = true; - emergencyAccess = true; - }; + testing.initrdBackdoor = true; + boot.initrd.systemd.enable = true; virtualisation.fileSystems."/".autoResize = true; }; testScript = '' import subprocess + with subtest("testing initrd backdoor"): + machine.wait_for_unit("initrd.target") + machine.succeed("systemctl status initrd-fs.target") + machine.switch_root() + with subtest("handover to stage-2 systemd works"): machine.wait_for_unit("multi-user.target") machine.succeed("systemd-analyze | grep -q '(initrd)'") # direct handover @@ -37,6 +40,7 @@ import ./make-test-python.nix ({ lib, pkgs, ... }: { subprocess.check_call(["qemu-img", "resize", "vm-state-machine/machine.qcow2", "+1G"]) machine.start() + machine.switch_root() newAvail = machine.succeed("df --output=avail / | sed 1d") assert int(oldAvail) < int(newAvail), "File system did not grow"