blob: 58081e1b6a1e8cd794de3063713c1a1e1c4a25a0 [file] [log] [blame]
# -*- mode: python -*-
# virtme-mkinitramfs: Generate an initramfs image for virtme
# Copyright © 2014 Andy Lutomirski
# Licensed under the GPLv2, which is available in the virtme distribution
# as a file called LICENSE with SHA-256 hash:
# 8177f97513213526df2cf6184d8ff986c675afb514d4e68a404010521b880643
import shutil
import io
import os.path
import shlex
import itertools
from . import cpiowriter
from . import modfinder
from . import virtmods
def make_base_layout(cw):
for dir in (b'lib', b'bin', b'var', b'etc', b'newroot', b'dev', b'proc',
b'tmproot', b'run_virtme', b'run_virtme/data', b'run_virtme/guesttools'):
cw.mkdir(dir, 0o755)
cw.symlink(b'bin', b'sbin')
cw.symlink(b'lib', b'lib64')
def make_dev_nodes(cw):
cw.mkchardev(b'dev/null', (1, 3), mode=0o666)
cw.mkchardev(b'dev/kmsg', (1, 11), mode=0o666)
cw.mkchardev(b'dev/console', (5, 1), mode=0o660)
def install_busybox(cw, config):
with open(config.busybox, 'rb') as busybox:
cw.write_file(name=b'bin/busybox', body=busybox, mode=0o755)
for tool in ('sh', 'mount', 'umount', 'switch_root', 'sleep', 'mkdir',
'mknod', 'insmod', 'cp', 'cat'):
cw.symlink(b'busybox', ('bin/%s' % tool).encode('ascii'))
cw.mkdir(b'bin/real_progs', mode=0o755)
def install_modprobe(cw):
cw.write_file(name=b'bin/modprobe', body=b'\n'.join([
b'#!/bin/sh',
b'echo "virtme: initramfs does not have module $3" >/dev/console',
]), mode=0o755)
_LOGFUNC = """log() {
if [[ -e /dev/kmsg ]]; then
echo "<6>virtme initramfs: $*" >/dev/kmsg
else
echo "virtme initramfs: $*"
fi
}
"""
def install_modules(cw, modfiles):
cw.mkdir(b'modules', 0o755)
paths = []
for mod in modfiles:
with open(mod, 'rb') as f:
modpath = 'modules/' + os.path.basename(mod)
paths.append(modpath)
cw.write_file(name=modpath.encode('ascii'),
body=f, mode=0o644)
script = _LOGFUNC + '\n'.join('log \'loading %s...\'; insmod %s' %
(os.path.basename(p), shlex.quote(p)) for p in paths)
cw.write_file(name=b'modules/load_all.sh',
body=script.encode('ascii'), mode=0o644)
_INIT = """#!/bin/sh
{logfunc}
source /modules/load_all.sh
log 'mounting hostfs...'
if ! /bin/mount -n -t 9p -o {access},version=9p2000.L,trans=virtio,access=any /dev/root /newroot/; then
echo "Failed to mount real root. We are stuck."
sleep 5
exit 1
fi
# Can we actually use /newroot/ as root?
if ! mount -t proc -o nosuid,noexec,nodev proc /newroot/proc 2>/dev/null; then
# QEMU 1.5 and below have a bug in virtfs that prevents mounting
# anything on top of a virtfs mount.
log "your host's virtfs is broken -- using a fallback tmpfs"
need_fallback_tmpfs=1
else
umount /newroot/proc # Don't leave garbage behind
fi
if ! [[ -d /newroot/run ]]; then
log "your guest's root does not have /run -- using a fallback tmpfs"
need_fallback_tmpfs=1
fi
if [[ "$need_fallback_tmpfs" != "" ]]; then
mount --move /newroot /tmproot
mount -t tmpfs root_workaround /newroot/
cd tmproot
mkdir /newroot/proc /newroot/sys /newroot/dev /newroot/run /newroot/tmp
for i in *; do
if [[ -d "$i" && \! -d "/newroot/$i" ]]; then
mkdir /newroot/"$i"
mount --bind "$i" /newroot/"$i"
fi
done
mknod /newroot/dev/null c 1 3
mount -o remount,ro -t tmpfs root_workaround /newroot
umount -l /tmproot
fi
mount -t tmpfs run /newroot/run
cp -a /run_virtme /newroot/run/virtme
# Find init
mount -t proc none /proc
for arg in `cat /proc/cmdline`; do
if [[ "${{arg%%=*}}" = "init" ]]; then
init="${{arg#init=}}"
break
fi
done
umount /proc
if [[ -z "$init" ]]; then
log 'no init= option'
exit 1
fi
log 'done; switching to real root'
exec /bin/switch_root /newroot "$init" "$@"
"""
def generate_init(config):
out = io.StringIO()
out.write(_INIT.format(
logfunc=_LOGFUNC,
access=config.access))
return out.getvalue().encode('utf-8')
class Config:
__slots__ = ['modfiles', 'virtme_data', 'virtme_init_path', 'busybox', 'access']
def __init__(self):
self.modfiles = []
self.virtme_data = {}
self.virtme_init_path = None
self.busybox = None
self.access = 'ro'
def mkinitramfs(out, config):
cw = cpiowriter.CpioWriter(out)
make_base_layout(cw)
make_dev_nodes(cw)
install_busybox(cw, config)
install_modprobe(cw)
if config.modfiles is not None:
install_modules(cw, config.modfiles)
for name,contents in config.virtme_data.items():
cw.write_file(b'run_virtme/data/' + name, body=contents, mode=0o755)
cw.write_file(b'init', body=generate_init(config),
mode=0o755)
cw.write_trailer()
def find_busybox(root, is_native):
for p in itertools.product(['usr/local', 'usr', ''],
['bin', 'sbin'],
['', '-static']):
path = os.path.join(root, p[0], p[1], 'busybox' + p[2])
if os.path.isfile(path):
return path
if is_native:
# Try the host's busybox, if any
return shutil.which('busybox')
# We give up.
return None