diskimage-builder/diskimage_builder/elements/rpm-distro/cleanup.d/99-selinux-fixfiles-restore

#!/bin/bash

if [ ${DIB_DEBUG_TRACE:-1} -gt 0 ]; then
    set -x
fi
set -eu
set -o pipefail

# parser isn't smart enough to figure out \
# dib-lint: disable=safe_sudo

# Here be dragons ... a previous dragon slayer helpfully pointed out in
#   http://www.spinics.net/lists/selinux/msg17379.html
#
#   Not all of the contexts defined by the offline system's
#   file_contexts may be valid under the policy of the host on which
#   you are running (e.g.  if they run different distributions or even
#   different releases of the same distribution), which will normally
#   prevent setting those contexts (the kernel won't recognize them).
#   If you have this issue, you'll need to run setfiles as root in a
#   special domain, setfiles_mac_t, that is allowed to set contexts
#   unknown to the host policy, and likely chrooted so that it doesn't
#   ask the kernel whether the contexts are valid via
#   /sys/fs/selinux/context.  That is how livecd-creator supported
#   creating images for other releases.

# One issue you might see without fixing selinux file labels is sshd
# will run in the kernel_t domain instead of the sshd_t domain, making
# ssh connections fail with "Unable to get valid context for <user>"
# error message.  Other failures will occur too.

# XXX: is it really valid to build rpm-distros without this?
if [[ ! -f ${TARGET_ROOT}/etc/selinux/targeted/contexts/files/file_contexts ]]; then
    echo "No selinux policy found in chroot, skipping..."
    exit 0
fi

if [[ ! -x ${TARGET_ROOT}/usr/sbin/setfiles ]]; then
    echo "Can not find setfiles in chroot!"
    exit 1
fi

# If we're on a selinux system, enable permissive mode for
# setfiles_mac_t so we can relabel within the chroot without concern
# for whatever policy is in the host kernel.  We will run under
# "runcon" to specifically allow this
_runcon=""
if [[ -d /sys/fs/selinux ]] && selinuxenabled; then
    sudo semanage permissive -a setfiles_mac_t
    _runcon="runcon -t setfiles_mac_t -- "
fi

# setfiles in > Fedora 26 added this flag:
#   do not read /proc/mounts to obtain a list of
#   non-seclabel mounts to be excluded from relabeling
#   checks.  Setting this option is useful where there is
#   a non-seclabel fs mounted with a seclabel fs
# this describes our situation of being on a loopback device on
# an ubuntu system, say.  See also
#  https://bugzilla.redhat.com/show_bug.cgi?id=1472709
_dash_m=""
if [[ $DISTRO_NAME == "fedora" && $DIB_RELEASE -ge 26 ]]; then
    _dash_m+="-m"
fi

IFS='|' read -ra SPLIT_MOUNTS <<< "$DIB_MOUNTPOINTS"
for MOUNTPOINT in "${SPLIT_MOUNTS[@]}"; do
    if [ "${MOUNTPOINT}" != "/tmp/in_target.d" ] && [ "${MOUNTPOINT}" != "/dev" ] && [ "${MOUNTPOINT}" != "/boot/efi" ]; then
        if ! [ -z ${_runcon} ] && ! pgrep kauditd >/dev/null; then
            echo "*** SELinux enabled and kauditd not found, suggesting auditing support is disabled in the host kernel. setfiles will fail without this, please enable and rebuild"
            exit 1
        fi

        if [[ ${MOUNTPOINT} == "/" ]]; then
            # If you don't label /dev, /proc and /sys (the actual,
            # on-disk directory in the image) correctly, it will have
            # bad effects when things like systemd try to do things
            # like make network or process namespaces.  This generally
            # leads to obscure and hard-to-debug failures; [1] has
            # plenty of examples.
            #
            # But right now, /{dev,proc,sys} are mounted!  With the
            # extant block-device code, we do not have a point to
            # break in when these are unmounted, but before we've
            # unmounted everything.  So we do a hack; for the root
            # directory, we bind mount the target so we see the
            # underlying directories, and then run setfiles on that.
            #
            # XXX: we might be able to uncondtionally do this for all
            #      mountpoints?  leaving well enough alone for now...
            #
            # [1] https://bugzilla.redhat.com/show_bug.cgi?id=1663040
            TMP_BIND_MOUNT=$(mktemp -d)
            sudo mount --bind ${TARGET_ROOT} ${TMP_BIND_MOUNT}
            sudo ${_runcon} chroot ${TMP_BIND_MOUNT} \
                /usr/sbin/setfiles -F ${_dash_m} \
                /etc/selinux/targeted/contexts/files/file_contexts /
            sudo umount ${TMP_BIND_MOUNT}
            sudo rmdir ${TMP_BIND_MOUNT}
        else
            sudo ${_runcon} chroot ${TARGET_ROOT} \
                /usr/sbin/setfiles -F ${_dash_m} \
                /etc/selinux/targeted/contexts/files/file_contexts ${MOUNTPOINT}
        fi
    fi
done