From f23318d579700b901aa44061006a62c37274cda2 Mon Sep 17 00:00:00 2001
From: Ian Wienand <iwienand@redhat.com>
Date: Fri, 16 Aug 2019 15:40:39 +1000
Subject: [PATCH] rpm-distro: ensure we selinux relabel underlying directories

As described inline, we need to ensure the underlying directories in
the image are correctly labeled, or we get all manner of services
failing during boot with selinux in enforcing mode.  Although the
problem is generic, this first shows up in Fedora 30 as systemd has
become more strict about namespace failures (I think) [1].

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1663040#c22

Change-Id: I52c1cc719884879169b606b00651aa26f5b783f1
---
 .../cleanup.d/99-selinux-fixfiles-restore     | 35 +++++++++++++++++--
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/diskimage_builder/elements/rpm-distro/cleanup.d/99-selinux-fixfiles-restore b/diskimage_builder/elements/rpm-distro/cleanup.d/99-selinux-fixfiles-restore
index f177829ac..00caefa37 100755
--- a/diskimage_builder/elements/rpm-distro/cleanup.d/99-selinux-fixfiles-restore
+++ b/diskimage_builder/elements/rpm-distro/cleanup.d/99-selinux-fixfiles-restore
@@ -70,9 +70,38 @@ for MOUNTPOINT in "${SPLIT_MOUNTS[@]}"; do
             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
-        sudo ${_runcon} chroot ${TARGET_ROOT} \
-            /usr/sbin/setfiles -F ${_dash_m} \
-            /etc/selinux/targeted/contexts/files/file_contexts ${MOUNTPOINT}
+
+        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