207 lines
7.2 KiB
Nix
207 lines
7.2 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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diskSize = 1024; # MB
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in
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{
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imports = [ ../profiles/headless.nix ../profiles/qemu-guest.nix ./grow-partition.nix ];
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# https://cloud.google.com/compute/docs/tutorials/building-images
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networking.firewall.enable = mkDefault false;
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system.build.googleComputeImage = import ../../lib/make-disk-image.nix {
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name = "google-compute-image";
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postVM = ''
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PATH=$PATH:${pkgs.stdenv.lib.makeBinPath [ pkgs.gnutar pkgs.gzip ]}
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pushd $out
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mv $diskImage disk.raw
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tar -Szcf nixos-image-${config.system.nixosLabel}-${pkgs.stdenv.system}.raw.tar.gz disk.raw
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rm $out/disk.raw
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popd
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'';
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configFile = ./google-compute-config.nix;
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format = "raw";
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inherit diskSize;
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inherit config lib pkgs;
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};
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fileSystems."/" = {
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device = "/dev/disk/by-label/nixos";
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autoResize = true;
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};
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boot.kernelParams = [ "console=ttyS0" "panic=1" "boot.panic_on_fail" ];
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boot.initrd.kernelModules = [ "virtio_scsi" ];
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boot.kernelModules = [ "virtio_pci" "virtio_net" ];
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# Generate a GRUB menu. Amazon's pv-grub uses this to boot our kernel/initrd.
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boot.loader.grub.device = "/dev/sda";
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boot.loader.timeout = 0;
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# Don't put old configurations in the GRUB menu. The user has no
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# way to select them anyway.
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boot.loader.grub.configurationLimit = 0;
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# Allow root logins only using the SSH key that the user specified
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# at instance creation time.
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services.openssh.enable = true;
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services.openssh.permitRootLogin = "prohibit-password";
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services.openssh.passwordAuthentication = mkDefault false;
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# Force getting the hostname from Google Compute.
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networking.hostName = mkDefault "";
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# Always include cryptsetup so that NixOps can use it.
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environment.systemPackages = [ pkgs.cryptsetup ];
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# Configure default metadata hostnames
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networking.extraHosts = ''
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169.254.169.254 metadata.google.internal metadata
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'';
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networking.timeServers = [ "metadata.google.internal" ];
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networking.usePredictableInterfaceNames = false;
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systemd.services.fetch-ssh-keys =
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{ description = "Fetch host keys and authorized_keys for root user";
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wantedBy = [ "sshd.service" ];
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before = [ "sshd.service" ];
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after = [ "network-online.target" ];
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wants = [ "network-online.target" ];
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script = let wget = "${pkgs.wget}/bin/wget --retry-connrefused -t 15 --waitretry=10 --header='Metadata-Flavor: Google'";
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mktemp = "mktemp --tmpdir=/run"; in
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''
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# When dealing with cryptographic keys, we want to keep things private.
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umask 077
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# Don't download the SSH key if it has already been downloaded
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if ! [ -s /root/.ssh/authorized_keys ]; then
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echo "obtaining SSH key..."
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mkdir -m 0700 -p /root/.ssh
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AUTH_KEYS=$(${mktemp})
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${wget} -O $AUTH_KEYS http://metadata.google.internal/0.1/meta-data/authorized-keys
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if [ -s $AUTH_KEYS ]; then
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KEY_PUB=$(${mktemp})
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cat $AUTH_KEYS | cut -d: -f2- > $KEY_PUB
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if ! grep -q -f $KEY_PUB /root/.ssh/authorized_keys; then
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cat $KEY_PUB >> /root/.ssh/authorized_keys
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echo "New key added to authorized_keys."
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fi
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chmod 600 /root/.ssh/authorized_keys
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rm -f $KEY_PUB
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else
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echo "Downloading http://metadata.google.internal/0.1/meta-data/authorized-keys failed."
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false
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fi
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rm -f $AUTH_KEYS
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fi
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countKeys=0
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${flip concatMapStrings config.services.openssh.hostKeys (k :
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let kName = baseNameOf k.path; in ''
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PRIV_KEY=$(${mktemp})
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echo "trying to obtain SSH private host key ${kName}"
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${wget} -O $PRIV_KEY http://metadata.google.internal/0.1/meta-data/attributes/${kName} && :
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if [ $? -eq 0 -a -s $PRIV_KEY ]; then
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countKeys=$((countKeys+1))
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mv -f $PRIV_KEY ${k.path}
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echo "Downloaded ${k.path}"
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chmod 600 ${k.path}
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${config.programs.ssh.package}/bin/ssh-keygen -y -f ${k.path} > ${k.path}.pub
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chmod 644 ${k.path}.pub
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else
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echo "Downloading http://metadata.google.internal/0.1/meta-data/attributes/${kName} failed."
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fi
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rm -f $PRIV_KEY
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''
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)}
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if [[ $countKeys -le 0 ]]; then
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echo "failed to obtain any SSH private host keys."
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false
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fi
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'';
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serviceConfig.Type = "oneshot";
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serviceConfig.RemainAfterExit = true;
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serviceConfig.StandardError = "journal+console";
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serviceConfig.StandardOutput = "journal+console";
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};
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# Setings taken from https://cloud.google.com/compute/docs/tutorials/building-images#providedkernel
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boot.kernel.sysctl = {
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# enables syn flood protection
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"net.ipv4.tcp_syncookies" = mkDefault "1";
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# ignores source-routed packets
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"net.ipv4.conf.all.accept_source_route" = mkDefault "0";
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# ignores source-routed packets
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"net.ipv4.conf.default.accept_source_route" = mkDefault "0";
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# ignores ICMP redirects
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"net.ipv4.conf.all.accept_redirects" = mkDefault "0";
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# ignores ICMP redirects
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"net.ipv4.conf.default.accept_redirects" = mkDefault "0";
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# ignores ICMP redirects from non-GW hosts
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"net.ipv4.conf.all.secure_redirects" = mkDefault "1";
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# ignores ICMP redirects from non-GW hosts
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"net.ipv4.conf.default.secure_redirects" = mkDefault "1";
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# don't allow traffic between networks or act as a router
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"net.ipv4.ip_forward" = mkDefault "0";
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# don't allow traffic between networks or act as a router
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"net.ipv4.conf.all.send_redirects" = mkDefault "0";
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# don't allow traffic between networks or act as a router
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"net.ipv4.conf.default.send_redirects" = mkDefault "0";
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# reverse path filtering - IP spoofing protection
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"net.ipv4.conf.all.rp_filter" = mkDefault "1";
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# reverse path filtering - IP spoofing protection
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"net.ipv4.conf.default.rp_filter" = mkDefault "1";
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# ignores ICMP broadcasts to avoid participating in Smurf attacks
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"net.ipv4.icmp_echo_ignore_broadcasts" = mkDefault "1";
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# ignores bad ICMP errors
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"net.ipv4.icmp_ignore_bogus_error_responses" = mkDefault "1";
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# logs spoofed, source-routed, and redirect packets
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"net.ipv4.conf.all.log_martians" = mkDefault "1";
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# log spoofed, source-routed, and redirect packets
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"net.ipv4.conf.default.log_martians" = mkDefault "1";
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# implements RFC 1337 fix
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"net.ipv4.tcp_rfc1337" = mkDefault "1";
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# randomizes addresses of mmap base, heap, stack and VDSO page
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"kernel.randomize_va_space" = mkDefault "2";
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# provides protection from ToCToU races
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"fs.protected_hardlinks" = mkDefault "1";
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# provides protection from ToCToU races
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"fs.protected_symlinks" = mkDefault "1";
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# makes locating kernel addresses more difficult
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"kernel.kptr_restrict" = mkDefault "1";
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# set ptrace protections
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"kernel.yama.ptrace_scope" = mkOverride 500 "1";
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# set perf only available to root
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"kernel.perf_event_paranoid" = mkDefault "2";
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};
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}
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