I just read that in certain situations you should also protect access to your GRUB2 menu by setting a password and may be refining acces by adding --unrestricted or --users as arguments to menuentries und submenus.

I read the corresponding pages in the Ubuntu Community Documentation and the Arch Wiki. So, I created /etc/grub.d/01_security, stored usernames and passwords in there, made the file executable and ran update-grub. This is working as intended, every action in the menu prompts for username and password, but I also want to modify the automatically generated entries to either restrict them to certain users (via --users) or make them available for everyone, but not editable by everyone (via --unrestricted).

I was able to find the proper lines in 10_linux and edit them accordingly, however I'd love to see an easier solution. Perhaps an option like GRUB_DISABLE_RECOVERY="true" or GRUB_DISABLE_OS_PROBER=true in /etc/default/grub for easy (re)configuration (for linux and os-prober generated entries).

Here's a diff from my 13.10 installation:

$ diff /etc/grub.d/10_linux /etc/grub.d/10_linux_bak
123c123
<       echo "menuentry '$(echo "$title" | grub_quote)' ${CLASS} --unrestriced \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^$
---
>       echo "menuentry '$(echo "$title" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^/$submenu_inde$
125c125
<       echo "menuentry '$(echo "$os" | grub_quote)' ${CLASS} --unrestricted \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_$
---
>       echo "menuentry '$(echo "$os" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_indentation/"
323c323
<     echo "submenu --unrestricted '$(gettext_printf "Advanced options for %s" "${OS}" | grub_quote)' \$menuentry_id_option 'gnulinux-advanced-$boot_device_$
---
>     echo "submenu '$(gettext_printf "Advanced options for %s" "${OS}" | grub_quote)' \$menuentry_id_option 'gnulinux-advanced-$boot_device_id' {"

tl;dr: I'd love the see a simple solution for GRUB2 entries that cannot be modified without a password or are limited to certain users. (Yes, GRUB_DISABLE_RECOVERY="true" is active.)