mirror of
https://gitlab.postmarketos.org/postmarketOS/pmbootstrap.git
synced 2025-07-24 21:15:10 +03:00
be5e18cf99
Rework how we handle binfmt_misc so it will work inside a user namespace. * Use a custom mountpoint (only accessible inside the mount namespace), this is the crux of the change, allowing us to mount it as non-root and avoid messing with any host configs too! * No longer explicitly modprobe binfmt_misc, any modern system should probe it automatically when we try to mount it... I think so anyways heh Signed-off-by: Casey Connolly <kcxt@postmarketos.org>
91 lines
3.1 KiB
Python
91 lines
3.1 KiB
Python
# Copyright 2023 Oliver Smith
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# SPDX-License-Identifier: GPL-3.0-or-later
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import os
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from pmb.core.arch import Arch
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from pmb.core.chroot import Chroot
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from pmb.helpers import logging
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import pmb.config
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def is_registered(arch_qemu: str | Arch) -> bool:
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return os.path.exists(f"{pmb.config.binfmt_misc}/qemu-{arch_qemu}")
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# FIXME: Maybe this should use Arch instead of str.
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def parse_binfmt_info(arch_qemu: str) -> dict[str, str]:
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# Parse the info file
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full = {}
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info = pmb.config.pmb_src / "pmb/data/qemu-user-binfmt.txt"
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logging.verbose(f"parsing: {info}")
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with open(info) as handle:
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for line in handle:
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if line.startswith("#") or "=" not in line:
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continue
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split = line.split("=")
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key = split[0].strip()
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value = split[1]
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full[key] = value[1:-2]
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ret = {}
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logging.verbose("filtering by architecture: " + arch_qemu)
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for type in ["mask", "magic"]:
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key = arch_qemu + "_" + type
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if key not in full:
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raise RuntimeError(f"Could not find key {key} in binfmt info file: {info}")
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ret[type] = full[key]
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logging.verbose("=> " + str(ret))
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return ret
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def register(arch: Arch) -> None:
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"""
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Get arch, magic, mask.
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"""
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arch_qemu = arch.qemu()
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chroot = Chroot.native()
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# always make sure the qemu-<arch> binary is installed, since registering
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# may happen outside of this method (e.g. by OS)
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if f"qemu-{arch_qemu}" not in pmb.chroot.apk.installed(chroot):
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pmb.chroot.init(chroot)
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pmb.chroot.apk.install(["qemu-" + arch_qemu], chroot)
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# Check if we're already registered
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if is_registered(arch_qemu):
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return
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info = parse_binfmt_info(arch_qemu)
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# Build registration string
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# https://en.wikipedia.org/wiki/Binfmt_misc
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# :name:type:offset:magic:mask:interpreter:flags
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name = "qemu-" + arch_qemu
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type = "M"
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offset = ""
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magic = info["magic"]
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mask = info["mask"]
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# FIXME: this relies on a hack where we bind-mount the qemu interpreter into the foreign
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# chroot. This really shouldn't be needed, instead we should unshare pmbootstrap into
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# an Alpine chroot that would have the interpreter installed, then pass the 'F' flag which
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# allows the interpreter to always be run even when we're later in a chroot.
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interpreter = "/usr/bin/qemu-" + arch_qemu + "-static"
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flags = "C"
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code = ":".join(["", name, type, offset, magic, mask, interpreter, flags])
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# Register in binfmt_misc
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logging.info("Register qemu binfmt (" + arch_qemu + ")")
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register = f"{pmb.config.binfmt_misc}/register"
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pmb.helpers.run.root(["sh", "-c", 'echo "' + code + '" > ' + register])
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logging.warning("WARNING: FIXME: binfmt borked because no perms!")
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def unregister(arch: Arch) -> None:
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arch_qemu = arch.qemu()
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binfmt_file = f"{pmb.config.binfmt_misc}/qemu-" + arch_qemu
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if not os.path.exists(binfmt_file):
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return
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logging.info("Unregister qemu binfmt (" + arch_qemu + ")")
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# pmb.helpers.run.root(["sh", "-c", "echo -1 > " + binfmt_file])
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logging.warning("WARNING: FIXME: binfmt borked because no perms!")
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