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import ./make-test-python.nix {
name = "systemd-confinement";
machine = { pkgs, lib, ... }: let
testServer = pkgs.writeScript "testserver.sh" ''
#!${pkgs.runtimeShell}
export PATH=${lib.escapeShellArg "${pkgs.coreutils}/bin"}
${lib.escapeShellArg pkgs.runtimeShell} 2>&1
echo "exit-status:$?"
'';
testClient = pkgs.writeScriptBin "chroot-exec" ''
#!${pkgs.runtimeShell} -e
output="$(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: {
testScript,
config ? {},
serviceName ? "test${toString num}",
}: {
systemd.sockets.${serviceName} = {
description = "Socket for Test Service ${toString num}";
wantedBy = [ "sockets.target" ];
socketConfig.ListenStream = "/run/test${toString num}.sock";
socketConfig.Accept = true;
};
systemd.services."${serviceName}@" = {
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 (''
machine.succeed("echo ${toString num} > /teststep")
'' + testScript);
};
in {
imports = lib.imap1 mkTestStep [
{ config.confinement.mode = "chroot-only";
testScript = ''
with subtest("chroot-only confinement"):
paths = machine.succeed('chroot-exec ls -1 / | paste -sd,').strip()
assert_eq(paths, "bin,nix,run")
uid = machine.succeed('chroot-exec id -u').strip()
assert_eq(uid, "0")
machine.succeed("chroot-exec chown 65534 /bin")
'';
}
{ testScript = ''
with subtest("full confinement with APIVFS"):
machine.fail("chroot-exec ls -l /etc")
machine.fail("chroot-exec chown 65534 /bin")
assert_eq(machine.succeed('chroot-exec id -u').strip(), "0")
machine.succeed("chroot-exec chown 0 /bin")
'';
}
{ config.serviceConfig.BindReadOnlyPaths = [ "/etc" ];
testScript = ''
with subtest("check existence of bind-mounted /etc"):
passwd = machine.succeed('chroot-exec cat /etc/passwd').strip()
assert len(passwd) > 0, "/etc/passwd must not be empty"
'';
}
{ config.serviceConfig.User = "chroot-testuser";
config.serviceConfig.Group = "chroot-testgroup";
testScript = ''
with subtest("check if User/Group really runs as non-root"):
machine.succeed("chroot-exec ls -l /dev")
uid = machine.succeed('chroot-exec id -u').strip()
assert uid != "0", "UID of chroot-testuser shouldn't be 0"
machine.fail("chroot-exec touch /bin/test")
'';
}
(let
symlink = pkgs.runCommand "symlink" {
target = pkgs.writeText "symlink-target" "got me\n";
} "ln -s \"$target\" \"$out\"";
in {
config.confinement.packages = lib.singleton symlink;
testScript = ''
with subtest("check if symlinks are properly bind-mounted"):
machine.fail("chroot-exec test -e /etc")
text = machine.succeed('chroot-exec cat ${symlink}').strip()
assert_eq(text, "got me")
'';
})
{ config.serviceConfig.User = "chroot-testuser";
config.serviceConfig.Group = "chroot-testgroup";
config.serviceConfig.StateDirectory = "testme";
testScript = ''
with subtest("check if StateDirectory works"):
machine.succeed("chroot-exec touch /tmp/canary")
machine.succeed('chroot-exec "echo works > /var/lib/testme/foo"')
machine.succeed('test "$(< /var/lib/testme/foo)" = works')
machine.succeed("test ! -e /tmp/canary")
'';
}
{ testScript = ''
with subtest("check if /bin/sh works"):
machine.succeed(
"chroot-exec test -e /bin/sh",
'test "$(chroot-exec \'/bin/sh -c "echo bar"\')" = bar',
)
'';
}
{ config.confinement.binSh = null;
testScript = ''
with subtest("check if suppressing /bin/sh works"):
machine.succeed("chroot-exec test ! -e /bin/sh")
machine.succeed('test "$(chroot-exec \'/bin/sh -c "echo foo"\')" != foo')
'';
}
{ config.confinement.binSh = "${pkgs.hello}/bin/hello";
testScript = ''
with subtest("check if we can set /bin/sh to something different"):
machine.succeed("chroot-exec test -e /bin/sh")
machine.succeed('test "$(chroot-exec /bin/sh -g foo)" = foo')
'';
}
{ config.environment.FOOBAR = pkgs.writeText "foobar" "eek\n";
testScript = ''
with subtest("check if only Exec* dependencies are included"):
machine.succeed('test "$(chroot-exec \'cat "$FOOBAR"\')" != eek')
'';
}
{ config.environment.FOOBAR = pkgs.writeText "foobar" "eek\n";
config.confinement.fullUnit = true;
testScript = ''
with subtest("check if all unit dependencies are included"):
machine.succeed('test "$(chroot-exec \'cat "$FOOBAR"\')" = eek')
'';
}
{ serviceName = "shipped-unitfile";
config.confinement.mode = "chroot-only";
testScript = ''
with subtest("check if shipped unit file still works"):
machine.succeed(
'chroot-exec \'kill -9 $$ 2>&1 || :\' | '
'grep -q "Too many levels of symbolic links"'
)
'';
}
];
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.systemd.packages = lib.singleton (pkgs.writeTextFile {
name = "shipped-unitfile";
destination = "/etc/systemd/system/shipped-unitfile@.service";
text = ''
[Service]
SystemCallFilter=~kill
SystemCallErrorNumber=ELOOP
'';
});
config.users.groups.chroot-testgroup = {};
config.users.users.chroot-testuser = {
isSystemUser = true;
description = "Chroot Test User";
group = "chroot-testgroup";
};
};
testScript = { nodes, ... }: ''
def assert_eq(a, b):
assert a == b, f"{a} != {b}"
machine.wait_for_unit("multi-user.target")
'' + nodes.machine.config.__testSteps;
}
|