nixpkgs/nixos/tests/systemd-confinement/default.nix
2024-07-01 08:49:45 +02:00

275 lines
9.4 KiB
Nix

import ../make-test-python.nix {
name = "systemd-confinement";
nodes.machine = { pkgs, lib, ... }: let
testLib = pkgs.python3Packages.buildPythonPackage {
name = "confinement-testlib";
unpackPhase = ''
cat > setup.py <<EOF
from setuptools import setup
setup(name='confinement-testlib', py_modules=["checkperms"])
EOF
cp ${./checkperms.py} checkperms.py
'';
};
mkTest = name: testScript: pkgs.writers.writePython3 "${name}.py" {
libraries = [ pkgs.python3Packages.pytest testLib ];
} ''
# This runs our test script by using pytest's assertion rewriting, so
# that whenever we use "assert <something>", the actual values are
# printed rather than getting a generic AssertionError or the need to
# pass an explicit assertion error message.
import ast
from pathlib import Path
from _pytest.assertion.rewrite import rewrite_asserts
script = Path('${pkgs.writeText "${name}-main.py" ''
import errno, os, pytest, signal
from subprocess import run
from checkperms import Accessibility, assert_permissions
${testScript}
''}') # noqa
filename = str(script)
source = script.read_bytes()
tree = ast.parse(source, filename=filename)
rewrite_asserts(tree, source, filename)
exec(compile(tree, filename, 'exec', dont_inherit=True))
'';
mkTestStep = num: {
description,
testScript,
config ? {},
serviceName ? "test${toString num}",
rawUnit ? null,
}: {
systemd.packages = lib.optional (rawUnit != null) (pkgs.writeTextFile {
name = serviceName;
destination = "/etc/systemd/system/${serviceName}.service";
text = rawUnit;
});
systemd.services.${serviceName} = {
inherit description;
requiredBy = [ "multi-user.target" ];
confinement = (config.confinement or {}) // { enable = true; };
serviceConfig = (config.serviceConfig or {}) // {
ExecStart = mkTest serviceName testScript;
Type = "oneshot";
};
} // removeAttrs config [ "confinement" "serviceConfig" ];
};
parametrisedTests = lib.concatMap ({ user, privateTmp }: let
withTmp = if privateTmp then "with PrivateTmp" else "without PrivateTmp";
serviceConfig = if user == "static-user" then {
User = "chroot-testuser";
Group = "chroot-testgroup";
} else if user == "dynamic-user" then {
DynamicUser = true;
} else {};
in [
{ description = "${user}, chroot-only confinement ${withTmp}";
config = {
confinement.mode = "chroot-only";
# Only set if privateTmp is true to ensure that the default is false.
serviceConfig = serviceConfig // lib.optionalAttrs privateTmp {
PrivateTmp = true;
};
};
testScript = if user == "root" then ''
assert os.getuid() == 0
assert os.getgid() == 0
assert_permissions({
'bin': Accessibility.READABLE,
'nix': Accessibility.READABLE,
'run': Accessibility.READABLE,
${lib.optionalString privateTmp "'tmp': Accessibility.STICKY,"}
${lib.optionalString privateTmp "'var': Accessibility.READABLE,"}
${lib.optionalString privateTmp "'var/tmp': Accessibility.STICKY,"}
})
'' else ''
assert os.getuid() != 0
assert os.getgid() != 0
assert_permissions({
'bin': Accessibility.READABLE,
'nix': Accessibility.READABLE,
'run': Accessibility.READABLE,
${lib.optionalString privateTmp "'tmp': Accessibility.STICKY,"}
${lib.optionalString privateTmp "'var': Accessibility.READABLE,"}
${lib.optionalString privateTmp "'var/tmp': Accessibility.STICKY,"}
})
'';
}
{ description = "${user}, full APIVFS confinement ${withTmp}";
config = {
# Only set if privateTmp is false to ensure that the default is true.
serviceConfig = serviceConfig // lib.optionalAttrs (!privateTmp) {
PrivateTmp = false;
};
};
testScript = if user == "root" then ''
assert os.getuid() == 0
assert os.getgid() == 0
assert_permissions({
'bin': Accessibility.READABLE,
'nix': Accessibility.READABLE,
${lib.optionalString privateTmp "'tmp': Accessibility.STICKY,"}
'run': Accessibility.WRITABLE,
'proc': Accessibility.SPECIAL,
'sys': Accessibility.SPECIAL,
'dev': Accessibility.WRITABLE,
${lib.optionalString privateTmp "'var': Accessibility.READABLE,"}
${lib.optionalString privateTmp "'var/tmp': Accessibility.STICKY,"}
})
'' else ''
assert os.getuid() != 0
assert os.getgid() != 0
assert_permissions({
'bin': Accessibility.READABLE,
'nix': Accessibility.READABLE,
${lib.optionalString privateTmp "'tmp': Accessibility.STICKY,"}
'run': Accessibility.STICKY,
'proc': Accessibility.SPECIAL,
'sys': Accessibility.SPECIAL,
'dev': Accessibility.SPECIAL,
'dev/shm': Accessibility.STICKY,
'dev/mqueue': Accessibility.STICKY,
${lib.optionalString privateTmp "'var': Accessibility.READABLE,"}
${lib.optionalString privateTmp "'var/tmp': Accessibility.STICKY,"}
})
'';
}
]) (lib.cartesianProduct {
user = [ "root" "dynamic-user" "static-user" ];
privateTmp = [ true false ];
});
in {
imports = lib.imap1 mkTestStep (parametrisedTests ++ [
{ description = "existence of bind-mounted /etc";
config.serviceConfig.BindReadOnlyPaths = [ "/etc" ];
testScript = ''
assert Path('/etc/passwd').read_text()
'';
}
(let
symlink = pkgs.runCommand "symlink" {
target = pkgs.writeText "symlink-target" "got me";
} "ln -s \"$target\" \"$out\"";
in {
description = "check if symlinks are properly bind-mounted";
config.confinement.packages = lib.singleton symlink;
testScript = ''
assert Path('${symlink}').read_text() == 'got me'
'';
})
{ description = "check if StateDirectory works";
config.serviceConfig.User = "chroot-testuser";
config.serviceConfig.Group = "chroot-testgroup";
config.serviceConfig.StateDirectory = "testme";
# We restart on purpose here since we want to check whether the state
# directory actually persists.
config.serviceConfig.Restart = "on-failure";
config.serviceConfig.RestartMode = "direct";
testScript = ''
assert not Path('/tmp/canary').exists()
Path('/tmp/canary').touch()
if (foo := Path('/var/lib/testme/foo')).exists():
assert Path('/var/lib/testme/foo').read_text() == 'works'
else:
Path('/var/lib/testme/foo').write_text('works')
print('<4>Exiting with failure to check persistence on restart.')
raise SystemExit(1)
'';
}
{ description = "check if /bin/sh works";
testScript = ''
assert Path('/bin/sh').exists()
result = run(
['/bin/sh', '-c', 'echo -n bar'],
capture_output=True,
check=True,
)
assert result.stdout == b'bar'
'';
}
{ description = "check if suppressing /bin/sh works";
config.confinement.binSh = null;
testScript = ''
assert not Path('/bin/sh').exists()
with pytest.raises(FileNotFoundError):
run(['/bin/sh', '-c', 'echo foo'])
'';
}
{ description = "check if we can set /bin/sh to something different";
config.confinement.binSh = "${pkgs.hello}/bin/hello";
testScript = ''
assert Path('/bin/sh').exists()
result = run(
['/bin/sh', '-g', 'foo'],
capture_output=True,
check=True,
)
assert result.stdout == b'foo\n'
'';
}
{ description = "check if only Exec* dependencies are included";
config.environment.FOOBAR = pkgs.writeText "foobar" "eek";
testScript = ''
with pytest.raises(FileNotFoundError):
Path(os.environ['FOOBAR']).read_text()
'';
}
{ description = "check if fullUnit includes all dependencies";
config.environment.FOOBAR = pkgs.writeText "foobar" "eek";
config.confinement.fullUnit = true;
testScript = ''
assert Path(os.environ['FOOBAR']).read_text() == 'eek'
'';
}
{ description = "check if shipped unit file still works";
config.confinement.mode = "chroot-only";
rawUnit = ''
[Service]
SystemCallFilter=~kill
SystemCallErrorNumber=ELOOP
'';
testScript = ''
with pytest.raises(OSError) as excinfo:
os.kill(os.getpid(), signal.SIGKILL)
assert excinfo.value.errno == errno.ELOOP
'';
}
]);
config.users.groups.chroot-testgroup = {};
config.users.users.chroot-testuser = {
isSystemUser = true;
description = "Chroot Test User";
group = "chroot-testgroup";
};
};
testScript = ''
machine.wait_for_unit("multi-user.target")
'';
}