919651277e
An RTC-less Pi boots at 1970; Tor then rejects the consensus and the unlock onion never publishes. Bake a clock floor (build epoch) into the initramfs and jump the clock forward to it before Tor starts, and pass a numeric tor_ntp= in the cmdline so busybox ntpd syncs without DNS. Proven on hardware: the onion unlock succeeded on a Pi 3 after this. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
118 lines
5.2 KiB
Python
118 lines
5.2 KiB
Python
"""initramfs-tools backend (Debian / Raspberry Pi OS).
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Debian does not use mkinitcpio; the LUKS unlock stack is cryptsetup-initramfs
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(reads /etc/crypttab, option ``initramfs``) + dropbear-initramfs (serves the
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passphrase prompt over SSH). Raspberry Pi OS ships without an initramfs, so we
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enable one in config.txt and regenerate with update-initramfs.
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NOTE: the exact dropbear-initramfs key path, the boot-partition mount point
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(/boot vs /boot/firmware) and the initramfs enable knob vary across Raspberry
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Pi OS releases; verify on the target release. This path is not exercised by the
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QEMU harness yet.
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"""
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import re
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from pathlib import Path
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from lim import config, fsutil, packages, runner, ui
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from lim.image.initramfs import keygen
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from lim.image.initramfs.base import InitramfsBackend
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from lim.image.plan import ImagePlan
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from lim.image.session import ImageSession, chroot_bash, install_packages
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# Numeric IP, not a hostname: the initramfs has no DNS resolver.
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_DEFAULT_NTP = "162.159.200.123"
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class InitramfsToolsBackend(InitramfsBackend):
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def luks_package_collection(self) -> str:
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return "server/luks-debian"
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def install_authorized_key(self, root: Path, authorized_keys: Path) -> None:
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# dropbear-initramfs (bookworm) reads /etc/dropbear/initramfs/authorized_keys.
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target = root / "etc/dropbear/initramfs/authorized_keys"
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ui.info(f"Adding {authorized_keys} to {target}...")
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runner.run(
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["install", "-D", "-m", "0600", str(authorized_keys), str(target)],
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sudo=True,
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)
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def install_tor_unlock(self, plan: ImagePlan, root: Path) -> str:
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ui.info("Setting up remote unlock via Tor onion service (initramfs-tools)...")
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install_packages(
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plan.distribution, root, " ".join(packages.get_packages("server/tor-debian"))
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)
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source_dir = config.CONFIGURATION_PATH / "initramfs-tools"
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for source, target, mode in (
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(source_dir / "tor_hook", root / "etc/initramfs-tools/hooks/tor", "0755"),
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(
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source_dir / "tor_premount",
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root / "etc/initramfs-tools/scripts/init-premount/tor",
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"0755",
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),
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(
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source_dir / "tor_bottom",
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root / "etc/initramfs-tools/scripts/init-bottom/tor",
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"0755",
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),
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(source_dir / "torrc", root / keygen.TORRC_STAGING_PATH, "0644"),
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):
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ui.info(f"Installing {target}...")
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runner.run(["install", "-D", "-m", mode, str(source), str(target)], sudo=True)
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onion_address = keygen.generate_onion_keys(root)
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ui.success(f"Onion unlock address: {onion_address}")
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ui.info(f"Unlock later with: torsocks ssh root@{onion_address}")
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return onion_address
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def register_encrypted_root(self, plan: ImagePlan, session: ImageSession, root: Path) -> None:
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fstab_path = root / "etc/fstab"
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fstab_line = (
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f"/dev/mapper/{session.root_mapper_name} / {plan.root_filesystem}"
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" defaults,noatime 0 1"
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)
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ui.info(f"Configuring {fstab_path}...")
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# A stock image already mounts / by PARTUUID; drop it so the mapper wins.
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fsutil.drop_fstab_mount("/", fstab_path)
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fsutil.ensure_line_in_file(fstab_line, fstab_path)
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crypttab_path = root / "etc/crypttab"
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# `initramfs` bakes the mapping into the initramfs so cryptsetup-initramfs
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# unlocks the root before the pivot.
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crypttab_line = (
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f"{session.root_mapper_name} UUID={session.root_partition_uuid} none luks,initramfs"
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)
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ui.info(f"Configuring {crypttab_path}...")
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fsutil.ensure_line_in_file(crypttab_line, crypttab_path)
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def configure_initramfs(self, plan: ImagePlan, root: Path) -> None: # noqa: ARG002
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ui.info("Regenerating the Debian initramfs (update-initramfs)...")
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# Create for all installed kernels when none exists yet (Raspberry Pi OS
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# ships without one), else update the existing one. `-k all` avoids the
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# build host's `uname -r` leaking into the chroot.
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chroot_bash(
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root,
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"update-initramfs -c -k all 2>/dev/null || update-initramfs -u -k all",
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)
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def configure_bootloader(self, plan: ImagePlan, session: ImageSession, root: Path) -> None:
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hostname = (root / "etc/hostname").read_text().strip()
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boot = session.boot_mount_path
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config_txt = boot / "config.txt"
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if config_txt.is_file():
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ui.info(f"Enabling an initramfs in {config_txt}...")
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fsutil.ensure_line_in_file("auto_initramfs=1", config_txt)
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cmdline_txt = boot / "cmdline.txt"
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ui.info(f"Configuring {cmdline_txt}...")
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text = cmdline_txt.read_text().strip()
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text = re.sub(r"root=\S+", f"root=/dev/mapper/{session.root_mapper_name}", text)
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if "ip=" not in text:
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text = f"{text} ip=::::{hostname}:eth0:dhcp"
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if "net.ifnames=0" not in text:
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text = f"{text} net.ifnames=0"
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if plan.tor_unlock and "tor_ntp=" not in text:
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text = f"{text} tor_ntp={_DEFAULT_NTP}"
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cmdline_txt.write_text(text + "\n")
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ui.info(f"Content of {cmdline_txt}:{cmdline_txt.read_text()}")
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