From 98638b3f387049564c223627e633a4ca6405e73d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= Date: Sun, 27 Nov 2022 17:06:17 +0100 Subject: [PATCH] kexec-installer: generate networkd units instead of iproute This should be more robust when interfaces appear late. It also makes ipv6 support easier to implement. --- nix/kexec-installer.nix | 21 ++++-- nix/restore_routes.py | 156 +++++++++++++++++++++++----------------- 2 files changed, 103 insertions(+), 74 deletions(-) diff --git a/nix/kexec-installer.nix b/nix/kexec-installer.nix index f0df0e7..1066500 100644 --- a/nix/kexec-installer.nix +++ b/nix/kexec-installer.nix @@ -36,8 +36,11 @@ in { # save the networking config for later use if type -p ip &>/dev/null; then - ip --json addr > addrs.json - ip --json route > routes.json + ip -4 --json addr > addrs-v4.json + ip -4 --json addr > addrs-v6.json + + ip -6 --json route > routes-v4.json + ip -6 --json route > routes-v6.json else echo "Skip saving static network addresses because no iproute2 binary is available." 2>&1 echo "The image can depends only on DHCP to get network after reboot!" 2>&1 @@ -87,16 +90,20 @@ in { # Not really needed. Saves a few bytes and the only service we are running is sshd, which we want to be reachable. networking.firewall.enable = false; + systemd.network.enable = true; + networking.dhcpcd.enable = false; + # for detection if we are on kexec environment.etc.is_kexec.text = "true"; systemd.services.restoreNetwork = { - path = [ - pkgs.iproute2 - ]; + before = [ "network-pre.target" ]; + wants = [ "network-pre.target" ]; wantedBy = [ "multi-user.target" ]; - after = [ "network-online.target" ]; - serviceConfig.ExecStart = "${restoreNetwork} /root/network/addrs.json /root/network/routes.json"; + + serviceConfig.ExecStart = [ + "${restoreNetwork} /root/network/addrs-v4.json /root/network/addrs-v6.json /root/network/routes-v4.json /root/network/routes-v6.json" + ]; unitConfig.ConditionPathExists = [ "/root/network/addrs.json" diff --git a/nix/restore_routes.py b/nix/restore_routes.py index e35e012..e2d8ad7 100644 --- a/nix/restore_routes.py +++ b/nix/restore_routes.py @@ -1,94 +1,116 @@ import json import sys -import subprocess +from pathlib import Path +from typing import Any -def filter_interfaces(network): +def filter_interfaces(network: list[dict[str, Any]]) -> list[dict[str, Any]]: output = [] for net in network: - if net["ifname"] == "lo": + if net.get("link_type") == "loopback": + continue + if not net.get("address"): + # We need a mac address to match devices reliable continue addr_info = [] + has_dynamic_address = False for addr in net["addr_info"]: + # no link-local ipv4/ipv6 + if addr.get("scope") == "link": + continue + # do not explicitly configure addresses from dhcp or router advertisment if addr.get("dynamic", False): - pass - elif addr["local"].startswith("fe80"): - pass + has_dynamic_address = True + continue else: addr_info.append(addr) - if addr_info != []: + if addr_info != [] or has_dynamic_address: net["addr_info"] = addr_info output.append(net) return output +def filter_routes(routes: list[dict[str, Any]]) -> list[dict[str, Any]]: + filtered = [] + for route in routes: + # Filter out routes set by addresses with subnets, dhcp and router advertisment + if route.get("protocol") in ["dhcp", "kernel", "ra"]: + continue + filtered.append(route) + + return filtered + + +def generate_networkd_units( + interfaces: list[dict[str, Any]], routes: list[dict[str, Any]], directory: Path +) -> None: + directory.mkdir(exist_ok=True) + for interface in interfaces: + name = f"{interface['ifname']}.network" + addresses = [ + f"Address = {addr['local']}/{addr['prefixlen']}" + for addr in interface["addr_info"] + ] + + route_sections = [] + for route in routes: + if route["dev"] != interface["ifname"]: + continue + + route_section = f"[Route]" + if route["dst"] != "default": + # can be skipped for default routes + route_section += f"Destination = {route['dst']}\n" + gateway = route.get("gateway") + if gateway: + route_section += f"Gateway = {gateway}\n" + + # we may ignore on-link default routes here, but I don't see how + # they would be useful for internet connectivity anyway + route_sections.append(route_section) + + # FIXME in some networks we might not want to trust dhcp or router advertisments + unit = f""" +[Match] +MACAddress = {interface["address"]} + +[Network] +DHCP = yes +IPv6AcceptRA = yes +""" + unit += "\n".join(addresses) + unit += "\n" + "\n".join(route_sections) + (directory / name).write_text(unit) + + def main() -> None: - if len(sys.argv) < 3: - print(f"USAGE: {sys.argv[0]} addresses routes", file=sys.stderr) + if len(sys.argv) < 5: + print( + f"USAGE: {sys.argv[0]} addresses-v4 addresses-v6 routes-v4 routes-v6 [networkd-directory]", + file=sys.stderr, + ) sys.exit(1) with open(sys.argv[1]) as f: - addresses = json.load(f) + v4_addresses = json.load(f) with open(sys.argv[2]) as f: - routes = json.load(f) - relevant_interfaces = filter_interfaces(addresses) - current_interfaces = json.loads( - subprocess.run( - ["ip", "--json", "addr"], - capture_output=True, - check=True - ).stdout - ) + v6_addresses = json.load(f) + with open(sys.argv[3]) as f: + v4_routes = json.load(f) + with open(sys.argv[4]) as f: + v6_routes = json.load(f) - for interface in relevant_interfaces: - for current_interface in current_interfaces: - if "address" in interface and "address" in current_interface: - if interface["address"] == current_interface["address"]: - for addr in interface["addr_info"]: - subprocess.run( - [ - "ip", - "addr", - "add", - "dev", - current_interface["ifname"], - f'{addr["local"]}/{addr["prefixlen"]}', - ], - check=True - ) - for route in routes: - if route["dev"] == interface["ifname"]: - if route.get("gateway", False): - subprocess.run( - [ - "ip", - "route", - "add", - route["dst"], - "via", - route["gateway"], - "dev", - current_interface["ifname"], - "preference", - "1", - ], - check=True - ) - else: - subprocess.run( - [ - "ip", - "route", - "add", - route["dst"], - "dev", - current_interface["ifname"], - "preference", - "1", - ], - check=True - ) + if len(sys.argv) >= 5: + networkd_directory = Path(sys.argv[5]) + else: + networkd_directory = Path("/etc/systemd/network") + + addresses = v4_addresses + v6_addresses + relevant_interfaces = filter_interfaces(addresses) + relevant_routes = filter_routes(v4_routes) + filter_routes(v6_routes) + + generate_networkd_units(relevant_interfaces, relevant_routes, networkd_directory) if __name__ == "__main__":