Accessing file system outside the chroot jail

Question

We are working on creating a user on a CentOS system who would work in a chrooted environment only. While this works fine in general, we also want this user to be able to access some configuration files which we keep in /etc and /opt. Read only access is necessary as we don't want the user to be able to change these files. The questions is how to provide this read only access.

Answer 1

for directories, i would recommend mounting the directories as readonly

for DIR in $DIRECTORIES ; do
    mount --bind $DIR "$CHROOT_DIR$DIR" -o ro
done

For files, I guess you can just copy them into the chrooted environment each time. (Unless you need changes to them to be available immediately to the user, it should work.

for FILE in $FILES ; do
    cp $FILE "$CHROOT_DIR$FILE"
done

Answer 2

Apparently I found the answer myself. I used a utility called bindfs and remounted my host directories inside of chroot in read only mode as needed.