fix(dockerfile): set more lenient permissions on /home/runner

Currently, the permissions of /home/runner are 750. In some container
runtimes and Kubernetes distributions (including OpenShift), a
different uid/gid (not `runner`) may be used when running the image.

The runner expects to be able to read and execute scripts within the
home directory, and it will also write ephemeral files, diagnostic
data, etc. into the directory as well. Therefore, to support the
ability to use the runner as a user apart from `runner`, full 777
permissions are needed.

A longer-term change to consider which may improve the security
posture here would be to separate the executable portions of the
application (scripts, etc.) from the places where temporary data is
written, and control the permissions of these separately.

Signed-off-by: Caleb Xu <caxu@redhat.com>

Author: caxu-rh

images/Dockerfile

@@ -59,7 +59,8 @@ RUN adduser --disabled-password --gecos "" --uid 1001 runner \
     && usermod -aG sudo runner \
     && usermod -aG docker runner \
     && echo "%sudo   ALL=(ALL:ALL) NOPASSWD:ALL" > /etc/sudoers \
-    && echo "Defaults env_keep += \"DEBIAN_FRONTEND\"" >> /etc/sudoers
+    && echo "Defaults env_keep += \"DEBIAN_FRONTEND\"" >> /etc/sudoers \
+    && chmod 777 /home/runner
 
 WORKDIR /home/runner