[HELP NEEDED] Unable to figure out directory permissions

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cross-posted from: https://infosec.pub/post/15386345

Hi everyone,

This is my CONTAINERFILE for Bind9:

FROM debian

ENV LC_ALL C.UTF-8

# Update and upgrade system
RUN apt-get update -y && apt-get upgrade -y && apt-get dist-upgrade -y

# Install BIND 9 and sudo (for debugging if needed)
RUN apt-get install -y bind9 bind9-dnsutils bind9-libs bind9-utils sudo

# Configure permissions for BIND directories
RUN mkdir -p /var/cache/bind /var/lib/bind /var/log/bind
RUN chown -R bind:bind /var/cache/bind /var/lib/bind /var/log/bind
RUN chmod 664 /var/cache/bind /var/lib/bind /var/log/bind
RUN chmod -R 664 /var/cache/bind /var/lib/bind /var/log/bind

# Create and configure log files
RUN touch /var/log/bind/default.log /var/log/bind/update_debug.log /var/log/bind/security_info.log /var/log/bind/bind.log
RUN chown -R bind:bind /var/log/bind
RUN chmod 644 /var/log/bind/*.log

# Define volumes
VOLUME ["/etc/bind", "/var/cache/bind", "/var/lib/bind", "/var/log/bind"]

# Set the entrypoint to the named executable
ENTRYPOINT ["/usr/sbin/named"]

# Set the default command arguments for the named executable
CMD ["-g"]

I keep getting this error when I run it with podman:

26-Jul-2024 03:18:21.328 loading configuration from '/etc/bind/named.conf'
26-Jul-2024 03:18:21.328 directory '/var/cache/bind' is not writable
26-Jul-2024 03:18:21.332 /etc/bind/named.conf.options:2: parsing failed: permission denied

As you can see from the CONTAINERFILE, the bind user should be able to read and write to /var/cache/bind but for some reason it doesn't.

I have been at this for a while and I'm at my wits end. Your help is appreciated!

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4 Comments

Is named actually running as the bind user inside the container ? Maybe a USER bind line below the RUN lines will help.

It should technically do that already, but as extra insurance I'm running it with the -u bind flag in ENTRYPOINT. The problem was solved with a chmod 755

Make sure the user "bind" and whatever the owner of that folder outside of the container is, have the same user number.

Thank you, I'll keep that in mind. I didn't actually mount volumes into the container yet, the problem was solved upon changing to chmod 755