#!/bin/bash

# Copyright (C) 2021-2024 Thien Tran
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.

#Meant to be run on Ubuntu Pro Minimal

output(){
  echo -e '\e[36m'"$1"'\e[0m';
}

unpriv(){
  sudo -u nobody "$@"
}

virtualization=$(systemd-detect-virt)

# Compliance and updates
sudo systemctl mask debug-shell.service
echo 'Authorized uses only. All activity may be monitored and reported.' | sudo tee /etc/issue
echo 'Authorized uses only. All activity may be monitored and reported.' | sudo tee /etc/issue.net

# Setting umask to 077
umask 077
sudo sed -i 's/^UMASK.*/UMASK 077/g' /etc/login.defs
sudo sed -i 's/^HOME_MODE/#HOME_MODE/g' /etc/login.defs
sudo sed -i 's/^USERGROUPS_ENAB.*/USERGROUPS_ENAB no/g' /etc/login.defs

# Make home directory private
sudo chmod 700 /home/*

# Setup NTS
sudo systemctl disable --now systemd-timesyncd
sudo systemctl mask systemd-timesyncd
sudo apt install -y chrony
unpriv curl https://raw.githubusercontent.com/GrapheneOS/infrastructure/main/chrony.conf | sudo tee /etc/chrony/chrony.conf
sudo systemctl restart chronyd

# Harden SSH
unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/ssh/sshd_config.d/10-custom.conf | sudo tee /etc/ssh/sshd_config.d/10-custom.conf
sudo chmod 644 /etc/ssh/sshd_config.d/10-custom.conf
unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/ssh/ssh_config.d/10-custom.conf | sudo tee /etc/ssh/ssh_config.d/10-custom.conf
sudo chmod 644 /etc/ssh/ssh_config.d/10-custom.conf
sudo mkdir -p /etc/systemd/system/ssh.service.d
unpriv curl https://raw.githubusercontent.com/GrapheneOS/infrastructure/main/systemd/system/sshd.service.d/local.conf | sudo tee /etc/systemd/system/ssh.service.d/override.conf
sudo systemctl daemon-reload
sudo systemctl restart ssh

# Security kernel settings
unpriv curl https://raw.githubusercontent.com/secureblue/secureblue/live/config/files/usr/etc/modprobe.d/blacklist.conf | sudo tee /etc/modprobe.d/server-blacklist.conf
sudo chmod 644 /etc/modprobe.d/server-blacklist.conf
unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/sysctl.d/99-server.conf | sudo tee /etc/sysctl.d/99-server.conf
sudo chmod 644 /etc/sysctl.d/99-server.conf
sudo sysctl -p

# Rebuild initramfs
sudo update-initramfs -u

# Disable coredump
umask 022
unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/security/limits.d/30-disable-coredump.conf | sudo tee /etc/security/limits.d/30-disable-coredump.conf
sudo mkdir -p /etc/systemd/coredump.conf.d
unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/systemd/coredump.conf.d/disable.conf | sudo tee /etc/systemd/coredump.conf.d/disable.conf
umask 077

# Update GRUB config
if [ ! -d /boot/efi/EFI/ZBM ]; then
  # shellcheck disable=SC2016
  sed -i 's/splash/splash mitigations=auto,nosmt spectre_v2=on spectre_bhi=on spec_store_bypass_disable=on tsx=off kvm.nx_huge_pages=force nosmt=force l1d_flush=on spec_rstack_overflow=safe-ret gather_data_sampling=force reg_file_data_sampling=on random.trust_bootloader=off random.trust_cpu=off intel_iommu=on amd_iommu=force_isolation efi=disable_early_pci_dma iommu=force iommu.passthrough=0 iommu.strict=1 slab_nomerge init_on_alloc=1 init_on_free=1 pti=on vsyscall=none ia32_emulation=0 page_alloc.shuffle=1 randomize_kstack_offset=on debugfs=off console=tty0 console=ttyS0,115200/g' /etc/default/grub
  sudo update-grub
fi

# Disable telemetry
sudo systemctl disable --now apport.service
sudo systemctl mask apport.service

## Avoid phased updates
sudo apt install -y curl
unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/apt/apt.conf.d/99sane-upgrades | sudo tee /etc/apt/apt.conf.d/99sane-upgrades
sudo chmod 644 /etc/apt/apt.conf.d/99sane-upgrades

sudo apt update -y
sudo apt full-upgrade -y
sudo apt autoremove -y

## Install basic sysadmin tools
sudo apt install -y nano iputils-ping

# Install appropriate virtualization drivers
if [ "$virtualization" = 'kvm' ]; then
    sudo apt install -y qemu-guest-agent
fi

# Enable fstrim.timer
sudo systemctl enable --now fstrim.timer

### Differentiating bare metal and virtual installs

# Setup tuned
sudo apt install -y tuned
sudo systemctl enable --now tuned

if [ "$virtualization" = 'none' ]; then
    sudo tuned-adm profile latency-performance
else
    sudo tuned-adm profile virtual-guest
fi

# Setup fwupd
if [ "$virtualization" = 'none' ]; then
    sudo apt install -y fwupd
    echo 'UriSchemes=file;https' | sudo tee -a /etc/fwupd/fwupd.conf
    sudo systemctl restart fwupd
    mkdir -p /etc/systemd/system/fwupd-refresh.service.d
    unpriv curl https://raw.githubusercontent.com/TommyTran732/Linux-Setup-Scripts/main/etc/systemd/system/fwupd-refresh.service.d/override.conf | sudo tee /etc/systemd/system/fwupd-refresh.service.d/override.conf
    sudo systemctl daemon-reload
    sudo systemctl enable --now fwupd-refresh.timer
fi

# Setup unbound

sudo apt install -y unbound

echo 'server:
  trust-anchor-signaling: yes
  root-key-sentinel: yes
  tls-cert-bundle: /etc/ssl/certs/ca-certificates.crt

  hide-identity: yes
  hide-trustanchor: yes
  hide-version: yes
  deny-any: yes
  harden-algo-downgrade: yes
  harden-large-queries: yes
  harden-referral-path: yes
  ignore-cd-flag: yes
  max-udp-size: 3072
  module-config: "validator iterator"
  qname-minimisation-strict: yes
  unwanted-reply-threshold: 10000000
  use-caps-for-id: yes

  outgoing-port-permit: 1024-65535

  prefetch: yes
  prefetch-key: yes


forward-zone:
  name: "."
  forward-tls-upstream: yes
  forward-addr: 1.1.1.2@853#security.cloudflare-dns.com
  forward-addr: 1.0.0.2@853#security.cloudflare-dns.com
  forward-addr: 2606:4700:4700::1112@853#security.cloudflare-dns.com
  forward-addr: 2606:4700:4700::1002@853#security.cloudflare-dns.com' | sudo tee /etc/unbound/unbound.conf.d/custom.conf

mkdir -p /etc/systemd/system/unbound.service.d
echo $'[Service]
CapabilityBoundingSet=CAP_NET_BIND_SERVICE CAP_SETGID CAP_SETUID CAP_SYS_CHROOT CAP_SYS_RESOURCE CAP_NET_RAW
MemoryDenyWriteExecute=true
NoNewPrivileges=true
PrivateDevices=true
PrivateTmp=true
ProtectHome=true
ProtectClock=true
ProtectControlGroups=true
ProtectKernelLogs=true
ProtectKernelModules=true
# This breaks using socket options like \'so-rcvbuf\'. Explicitly disable for visibility.
ProtectKernelTunables=false
ProtectProc=invisible
RestrictAddressFamilies=AF_INET AF_INET6 AF_NETLINK AF_UNIX
RestrictRealtime=true
SystemCallArchitectures=native
SystemCallFilter=~@clock @cpu-emulation @debug @keyring @module mount @obsolete @resources
RestrictNamespaces=yes
LockPersonality=yes
RestrictSUIDSGID=yes
ReadWritePaths=@UNBOUND_RUN_DIR@ @UNBOUND_CHROOT_DIR@

# Below rules are needed when chroot is enabled (usually it\'s enabled by default).
# If chroot is disabled like chroot: "" then they may be safely removed.
TemporaryFileSystem=@UNBOUND_CHROOT_DIR@/dev:ro
TemporaryFileSystem=@UNBOUND_CHROOT_DIR@/run:ro
BindReadOnlyPaths=-/run/systemd/notify:@UNBOUND_CHROOT_DIR@/run/systemd/notify
BindReadOnlyPaths=-/dev/urandom:@UNBOUND_CHROOT_DIR@/dev/urandom
BindPaths=-/dev/log:@UNBOUND_CHROOT_DIR@/dev/log' | sudo tee /etc/systemd/system/unbound.service.d/override.conf

sudo systemctl daemon-reload
sudo systemctl restart unbound
sudo systemctl disable systemd-resolved

# Setup networking

# UFW Snap is strictly confined, unlike its .deb counterpart
sudo apt purge -y ufw
sudo snap install ufw
sudo ufw enable
sudo ufw allow SSH

sudo reboot