nixpkgs/nixos/tests/systemd-confinement.nix
aszlig 9e9af4f9c0
nixos/confinement: Allow to include the full unit
From @edolstra at [1]:

  BTW we probably should take the closure of the whole unit rather than
  just the exec commands, to handle things like Environment variables.

With this commit, there is now a "fullUnit" option, which can be enabled
to include the full closure of the service unit into the chroot.

However, I did not enable this by default, because I do disagree here
and *especially* things like environment variables or environment files
shouldn't be in the closure of the chroot.

For example if you have something like:

  { pkgs, ... }:

  {
    systemd.services.foobar = {
      serviceConfig.EnvironmentFile = ${pkgs.writeText "secrets" ''
        user=admin
        password=abcdefg
      '';
    };
  }

We really do not want the *file* to end up in the chroot, but rather
just the environment variables to be exported.

Another thing is that this makes it less predictable what actually will
end up in the chroot, because we have a "globalEnvironment" option that
will get merged in as well, so users adding stuff to that option will
also make it available in confined units.

I also added a big fat warning about that in the description of the
fullUnit option.

[1]: https://github.com/NixOS/nixpkgs/pull/57519#issuecomment-472855704

Signed-off-by: aszlig <aszlig@nix.build>
2019-03-14 20:04:33 +01:00

169 lines
5.9 KiB
Nix

import ./make-test.nix {
name = "systemd-confinement";
machine = { pkgs, lib, ... }: let
testServer = pkgs.writeScript "testserver.sh" ''
#!${pkgs.stdenv.shell}
export PATH=${lib.escapeShellArg "${pkgs.coreutils}/bin"}
${lib.escapeShellArg pkgs.stdenv.shell} 2>&1
echo "exit-status:$?"
'';
testClient = pkgs.writeScriptBin "chroot-exec" ''
#!${pkgs.stdenv.shell} -e
output="$(echo "$@" | nc -NU "/run/test$(< /teststep).sock")"
ret="$(echo "$output" | sed -nre '$s/^exit-status:([0-9]+)$/\1/p')"
echo "$output" | head -n -1
exit "''${ret:-1}"
'';
mkTestStep = num: { description, config ? {}, testScript }: {
systemd.sockets."test${toString num}" = {
description = "Socket for Test Service ${toString num}";
wantedBy = [ "sockets.target" ];
socketConfig.ListenStream = "/run/test${toString num}.sock";
socketConfig.Accept = true;
};
systemd.services."test${toString num}@" = {
description = "Confined Test Service ${toString num}";
confinement = (config.confinement or {}) // { enable = true; };
serviceConfig = (config.serviceConfig or {}) // {
ExecStart = testServer;
StandardInput = "socket";
};
} // removeAttrs config [ "confinement" "serviceConfig" ];
__testSteps = lib.mkOrder num ''
subtest '${lib.escape ["\\" "'"] description}', sub {
$machine->succeed('echo ${toString num} > /teststep');
${testScript}
};
'';
};
in {
imports = lib.imap1 mkTestStep [
{ description = "chroot-only confinement";
config.confinement.mode = "chroot-only";
testScript = ''
$machine->succeed(
'test "$(chroot-exec ls -1 / | paste -sd,)" = bin,nix',
'test "$(chroot-exec id -u)" = 0',
'chroot-exec chown 65534 /bin',
);
'';
}
{ description = "full confinement with APIVFS";
testScript = ''
$machine->fail(
'chroot-exec ls -l /etc',
'chroot-exec ls -l /run',
'chroot-exec chown 65534 /bin',
);
$machine->succeed(
'test "$(chroot-exec id -u)" = 0',
'chroot-exec chown 0 /bin',
);
'';
}
{ description = "check existence of bind-mounted /etc";
config.serviceConfig.BindReadOnlyPaths = [ "/etc" ];
testScript = ''
$machine->succeed('test -n "$(chroot-exec cat /etc/passwd)"');
'';
}
{ description = "check if User/Group really runs as non-root";
config.serviceConfig.User = "chroot-testuser";
config.serviceConfig.Group = "chroot-testgroup";
testScript = ''
$machine->succeed('chroot-exec ls -l /dev');
$machine->succeed('test "$(chroot-exec id -u)" != 0');
$machine->fail('chroot-exec touch /bin/test');
'';
}
(let
symlink = pkgs.runCommand "symlink" {
target = pkgs.writeText "symlink-target" "got me\n";
} "ln -s \"$target\" \"$out\"";
in {
description = "check if symlinks are properly bind-mounted";
config.confinement.packages = lib.singleton symlink;
testScript = ''
$machine->fail('chroot-exec test -e /etc');
$machine->succeed('chroot-exec cat ${symlink} >&2');
$machine->succeed('test "$(chroot-exec cat ${symlink})" = "got me"');
'';
})
{ description = "check if StateDirectory works";
config.serviceConfig.User = "chroot-testuser";
config.serviceConfig.Group = "chroot-testgroup";
config.serviceConfig.StateDirectory = "testme";
testScript = ''
$machine->succeed('chroot-exec touch /tmp/canary');
$machine->succeed('chroot-exec "echo works > /var/lib/testme/foo"');
$machine->succeed('test "$(< /var/lib/testme/foo)" = works');
$machine->succeed('test ! -e /tmp/canary');
'';
}
{ description = "check if /bin/sh works";
testScript = ''
$machine->succeed(
'chroot-exec test -e /bin/sh',
'test "$(chroot-exec \'/bin/sh -c "echo bar"\')" = bar',
);
'';
}
{ description = "check if suppressing /bin/sh works";
config.confinement.binSh = null;
testScript = ''
$machine->succeed(
'chroot-exec test ! -e /bin/sh',
'test "$(chroot-exec \'/bin/sh -c "echo foo"\')" != foo',
);
'';
}
{ description = "check if we can set /bin/sh to something different";
config.confinement.binSh = "${pkgs.hello}/bin/hello";
testScript = ''
$machine->succeed(
'chroot-exec test -e /bin/sh',
'test "$(chroot-exec /bin/sh -g foo)" = foo',
);
'';
}
{ description = "check if only Exec* dependencies are included";
config.environment.FOOBAR = pkgs.writeText "foobar" "eek\n";
testScript = ''
$machine->succeed('test "$(chroot-exec \'cat "$FOOBAR"\')" != eek');
'';
}
{ description = "check if all unit dependencies are included";
config.environment.FOOBAR = pkgs.writeText "foobar" "eek\n";
config.confinement.fullUnit = true;
testScript = ''
$machine->succeed('test "$(chroot-exec \'cat "$FOOBAR"\')" = eek');
'';
}
];
options.__testSteps = lib.mkOption {
type = lib.types.lines;
description = "All of the test steps combined as a single script.";
};
config.environment.systemPackages = lib.singleton testClient;
config.users.groups.chroot-testgroup = {};
config.users.users.chroot-testuser = {
description = "Chroot Test User";
group = "chroot-testgroup";
};
};
testScript = { nodes, ... }: ''
$machine->waitForUnit('multi-user.target');
${nodes.machine.config.__testSteps}
'';
}