Multiple Boot Modes for Better Security - an Implementation of Untrusted Root
This concept is generic. Works for both, hosts and VMs. Both, Whonix and non-Whonix (Kicksecure).
- 1 Grub Default Boot Menu Entries
- 2 boot modes considered too unimportant to be added to grub default boot menu
- 3 Use Cases for the Different Boot Modes
- 4 opt-out to get same behavior as old Whonix
- 5 /etc/grub.d file names
- 6 Terminology
- 7 Capabilities of secureroot vs superroot
- 8 Server Support
- 9 Implementation
- 10 Related
- 11 Footnotes
Grub Default Boot Menu Entries
PERSISTENT mode USER (For daily activities.)
LIVE mode USER (For daily activities.)
PERSISTENT mode SECUREADMIN (For software installation.)
PERSISTENT mode SUPERADMIN (Be very cautious!)
Recovery PERSISTENT mode SUPERADMIN (Be very cautious!)
LIVE mode SECUREADMIN
LIVE mode SUPERADMIN
Recovery LIVE mode SUPERADMIN
I don’t see good use cases for these. But could be convinced otherwise with user feedback.
If anyone cares about these, there could be files in
/etc/grub.d/ folder that add such entries but these files could be non-executable by default. Thereby
update-grub would ignore them. To opt-in into such modes, users could just run
sudo chmod +x /etc/grub.d/somenumber_name-of-boot-mode.
Also users who really want something special/custom would be able to add whatever they want to
/etc/grub.d/ folder / grub boot menu.
Also by using grub boot menu editing (key
e) at grub boot menu, kernel parameters can be adjusted and any combination would be possible.
Use Cases for the Different Boot Modes
PERSISTENT mode USER (For daily activities.): Useful for browsing, e-mail, chat, etc. or just letting an already set up and installed server run. Even upgrading through
LIVE mode USER (For daily activities.): Same as above but without persistence.
PERSISTENT mode SECUREADMIN (For software installation.): users could run
sudo apt install whatever-software-package, then reboot into USER. Editing
/etc/apt/sources.list.damong many other things [archive] prohibited for better security.
PERSISTENT mode SUPERADMIN (Be very cautious!): users could add foreign sources to
/etc/apt/sources.list.dor do anything (full freedom), then (optional but advisable) reboot to SECUREADMIN mode, install packages from third party repositories.
Recovery PERSISTENT mode SUPERADMIN (Be very cautious!): The usual recovery mode.
opt-out to get same behavior as old Whonix
Users who don’t like (any, multiple or all) of the new options...
PERSISTENT mode USER (For daily activities.)[A]
LIVE mode USER (For daily activities.)[B]
PERSISTENT mode SECUREADMIN (For software installation.)[C]
and who want "the old Whonix" "with unrestricted sudo" (
PERSISTENT mode SUPERADMIN) back, who don't want to see any of the new options [A], [B], [C]... These could just make these
/etc/grub.d folder / grub menu entries gone by running
sudo chmod -x /etc/grub.d/somenumber_name-of-boot-mode. (There could be a script to simplify that.)
/etc/grub.d file names
/etc/grub.d/10_linux PERSISTENT mode USER /etc/grub.d/11_linux_live LIVE mode USER /etc/grub.d/12_linux_secureadmin PERSISTENT mode SECUREADMIN /etc/grub.d/13_linux_secureadmin_live LIVE mode SECUREADMIN /etc/grub.d/14_linux_superadmin PERSISTENT mode SUPERADMIN /etc/grub.d/15_linux_superadmin_live LIVE mode SUPERADMIN /etc/grub.d/16_linux_recovery_mode PERSISTENT mode SUPERADMIN /etc/grub.d/17_linux_recovery_mode_live Recovery LIVE mode SUPERADMIN
Should stay in lexical order below files named
/etc/grub.d/20_ because that is already used by an existing script.
Note: some files will not be created in the first iteration (and not sure ever) - those listed in chapter
Boot modes considered too unimportant to be added to grub default boot menu: in my post above.
secure admin modevs user
secureroot: When booting into
secure admin mode, the user will be logged in as user
secureadmin mode, when running
sudo somethingthe command will effectively run as
super admin modevs user
superroot: When booting into
super admin mode, the user will be logged in as user
super admin mode, when running
sudo somethingthe command will effectively run as
untrusted root: A command running as
rootbut with restrictions applied by apparmor-profile-everything.
unrestricted root: When running
sudo something, the behavior will be the same as on most Linux distributions such as Debian where
rootcan do everything that
rootcan usually do on such Linux distributions.
Capabilities of secureroot vs superroot
secureroot will be untrusted root, therefore restricted but can still:
- install packages
- change most system settings
secureroot cannot by design:
- change anything that could lead to
- change the running kernel
- replace bootloader (only if APT does this due to an upgrade)
- uninstall certain packages required to enforce the separation of
superrootsuch as for example apparmor-profile-apparmor
superroot by design will be able to do everything.
grub boot menu isn’t easily accessible for many/most servers. How would these various boot modes be available for servers? No solution yet. See forum discussion: https://forums.whonix.org/t/multiple-boot-modes-for-better-security-persistent-user-live-user-persistent-admin-persistent-superadmin-persistent-recovery-mode/7708/50 [archive]
- https://github.com/Whonix/apparmor-profile-everything/tree/master/etc/grub.d [archive]
- https://github.com/Whonix/apparmor-profile-everything [archive]
- AppArmor for everything. APT, systemd, init, all systemd units, all applications. Mandatory Access Control. Security Hardening. [archive]
- disable newly (all) installed services by default [archive]
- Verified Boot
- Untrusted Root - improve Security by Restricting Root [archive]
- forum discussion, AppArmor for Complete System - Including init, PID1, Systemd, Everything! - Full System MAC policy [archive]
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