From fadca94b98dc0a849f5c01062d63393938235bda Mon Sep 17 00:00:00 2001 From: maxice8 Date: Tue, 26 Feb 2019 17:23:11 -0300 Subject: [PATCH] common: add chroot-style 'ethereal' --- common/chroot-style/ethereal.sh | 135 ++++++++++++++++++++++++++++++ common/xbps-src/shutils/chroot.sh | 1 + etc/defaults.conf | 7 ++ xbps-src | 2 +- 4 files changed, 144 insertions(+), 1 deletion(-) create mode 100755 common/chroot-style/ethereal.sh diff --git a/common/chroot-style/ethereal.sh b/common/chroot-style/ethereal.sh new file mode 100755 index 0000000000..f1421385c3 --- /dev/null +++ b/common/chroot-style/ethereal.sh @@ -0,0 +1,135 @@ +#!/bin/sh +# +# This chroot script uses symlinks to emulate being in a chroot using +# the host system as the masterdir +# +# It will damage your host system, only use it in disposable +# containers. +# +# 2 extra steps required when using this chroot-style: +# 1. Symlink / to masterdir inside the void-packages repo +# 2. write the arch of the host system, as dictated by xbps-uhelper arch +# into /.xbps_chroot_init +# +# The supported way to make use of thie chroot-style is to create +# a root filesystem that has base-chroot and git installed and +# have it inside a container engine like Docker. +# +# Docker example: +# $ mkdir -p /tmp/image +# $ xbps-install -y -r /tmp/image \ +# -R http://mirrors.servercentral.com/voidlinux/current \ +# -S base-chroot +# $ tar -pC /tmp/image -c . | sudo docker import - voidlinux/masterdir +# $ rm -rf /tmp/image +# # docker run --rm -it \ +# -e XBPS_CHROOT_CMD=ethereal \ +# -e XBPS_ALLOW_CHROOT_BREAKOUT=yes \ +# -v $(pwd):/hostrepo voidlinux/masterdir \ +# /bin/bash -c 'ln -s / /hostrepo/masterdir && /hostrepo/xbps-src pkg ' +# + +readonly MASTERDIR="$1" +readonly DISTDIR="$2" +readonly HOSTDIR="$3" +readonly EXTRA_ARGS="$4" +readonly CMD="$5" +shift 5 + +if [ -z "$MASTERDIR" -o -z "$DISTDIR" ]; then + echo "$0 MASTERDIR/DISTDIR not set" + exit 1 +fi + +msg_red() { + # error messages in bold/red + [ -n "$NOCOLORS" ] || printf >&2 "\033[1m\033[31m" + printf "=> ERROR: %s\\n" "$@" + [ -n "$NOCOLORS" ] || printf >&2 "\033[m" +} + +fake_mount() { + # If we already have a symlink from the desired place + # to the base location then just return 0 + if [ -L "$2" -a "$(readlink "$2")" = "$1" ]; then + return 0 + fi + + if [ -d "$2" ] && ! rmdir "$2" >/dev/null 2>&1; then + msg_red "Failed to remove $2, not empty ?\n" + exit 1 + fi + + [ -f "$2" -o -L "$2" ] && rm -f "$2" + + ln -s "$1" "$2" + echo "linked $1 -> $2" +} + +if [ "${XBPS_ALLOW_CHROOT_BREAKOUT}" != "yes" ]; then + msg_red "chroot-style 'ethereal' requires XBPS_ALLOW_CHROOT_BREAKOUT=yes\n" + msg_red "This chroot-style is meant for disposable containers and will destroy your system\n" + exit 1 +fi + +if [ ! -L "$MASTERDIR" -o "$(readlink "$MASTERDIR")" != "/" ]; then + msg_red "$MASTERDIR isn't symlinked to /!\n" + exit 1 +fi + +fake_mount "$DISTDIR" "$MASTERDIR"/void-packages + +# Do the same for hostdir +if [ -n "$HOSTDIR" ]; then + fake_mount "$HOSTDIR" "$MASTERDIR"/host +fi + +# xbps-src may send some other binds, parse them here +while getopts 'b:' c -- "$EXTRA_ARGS"; do + # Skip everything that's not a bind + [ "$c" = "b" ] || continue + + from="${OPTARG%:*}" + to="${OPTARG#*:}" + + fake_mount "$from" "$to" + + mounts="${mounts} $to" +done + +# Store current directory for returning later +OLDPWD="$(pwd)" + +# To give the illusion we entered the chroot, cd to / +cd / || { + msg_red "Failed to change directory to root!\n" + exit 1 ; } + +# Tell xbps-src that we are "in the chroot" +# Start with `env` so our environment var's stay the same +env IN_CHROOT=1 $CMD $@ + +# Store return of the command we care about +ret="$?" + +# Return to OLDPWD +cd "${OLDPWD}" + +# Remove the symlink and restore an empty dir to simulate +# an umount operation. +if [ -n "$HOSTDIR" ]; then + rm -f "$MASTERDIR"/host + mkdir -p "$MASTERDIR"/host +fi + +# Same as the operation above, do it all for all mountpoints +# that were passed to us. +for m in $mounts; do + rm -f "$m" + mkdir -p "$m" +done + +rm -f "$MASTERDIR"/void-packages +mkdir -p "$MASTERDIR"/void-packages + +exit $ret diff --git a/common/xbps-src/shutils/chroot.sh b/common/xbps-src/shutils/chroot.sh index 89437f02a3..50eb195a4b 100644 --- a/common/xbps-src/shutils/chroot.sh +++ b/common/xbps-src/shutils/chroot.sh @@ -216,6 +216,7 @@ chroot_handler() { env -i -- PATH="/usr/bin:/usr/sbin:$PATH" SHELL=/bin/sh \ HOME=/tmp IN_CHROOT=1 LC_COLLATE=C LANG=en_US.UTF-8 \ SOURCE_DATE_EPOCH="$SOURCE_DATE_EPOCH" \ + XBPS_ALLOW_CHROOT_BREAKOUT="$XBPS_ALLOW_CHROOT_BREAKOUT" \ $XBPS_COMMONDIR/chroot-style/${XBPS_CHROOT_CMD:=uunshare}.sh \ $XBPS_MASTERDIR $XBPS_DISTDIR "$XBPS_HOSTDIR" "$XBPS_CHROOT_CMD_ARGS" \ /void-packages/xbps-src $action $pkg diff --git a/etc/defaults.conf b/etc/defaults.conf index ea16e681d4..766ac3ef7f 100644 --- a/etc/defaults.conf +++ b/etc/defaults.conf @@ -114,6 +114,7 @@ XBPS_SUCMD="sudo /bin/sh -c" # - uchroot (uses xbps-uchroot(8), namespaces, setgid) # - proot (uses proot, external, does not need special permissions) # - bwrap (uses bwrap, external, does not need special permissions) +# - ethereal (uses root, needs no permissions, for disposable containers) # # The order is already set as shown above, but can be overriden below. # Additional arguments to the chroot style can be passed in via XBPS_CHROOT_CMD_ARGS. @@ -126,3 +127,9 @@ XBPS_SUCMD="sudo /bin/sh -c" # the HEAD commit time. # #XBPS_USE_BUILD_MTIME=yes + +# [OPTIONAL] +# When using the 'ethereal' chroot-style this switch must be activated, it is +# meant as safeguard against users casually destroying their systems +# +#XBPS_ALLOW_CHROOT_BREAKOUT=yes diff --git a/xbps-src b/xbps-src index 8a9e9dd2d4..2fc2823df1 100755 --- a/xbps-src +++ b/xbps-src @@ -577,7 +577,7 @@ if [ -n "${NO_COLOR+x}" ]; then fi chroot_check() { - if [ -f $XBPS_MASTERDIR/.xbps_chroot_init ]; then + if [ -f $XBPS_MASTERDIR/.xbps_chroot_init -o "$XBPS_CHROOT_CMD" = "ethereal" ]; then export CHROOT_READY=1 fi }