pyrox.dev
1{ config, lib, pkgs, ... }:
2
3with lib;
4let
5 diskSize = 1024; # MB
6 gce = pkgs.google-compute-engine;
7in
8{
9 imports = [ ../profiles/headless.nix ../profiles/qemu-guest.nix ];
10
11 system.build.googleComputeImage = import ../../lib/make-disk-image.nix {
12 name = "google-compute-image";
13 postVM = ''
14 PATH=$PATH:${pkgs.stdenv.lib.makeBinPath [ pkgs.gnutar pkgs.gzip ]}
15 pushd $out
16 mv $diskImage disk.raw
17 tar -Szcf nixos-image-${config.system.nixos.label}-${pkgs.stdenv.system}.raw.tar.gz disk.raw
18 rm $out/disk.raw
19 popd
20 '';
21 configFile = <nixpkgs/nixos/modules/virtualisation/google-compute-config.nix>;
22 format = "raw";
23 inherit diskSize;
24 inherit config lib pkgs;
25 };
26
27 fileSystems."/" = {
28 device = "/dev/disk/by-label/nixos";
29 autoResize = true;
30 };
31
32 boot.growPartition = true;
33 boot.kernelParams = [ "console=ttyS0" "panic=1" "boot.panic_on_fail" ];
34 boot.initrd.kernelModules = [ "virtio_scsi" ];
35 boot.kernelModules = [ "virtio_pci" "virtio_net" ];
36
37 # Generate a GRUB menu. Amazon's pv-grub uses this to boot our kernel/initrd.
38 boot.loader.grub.device = "/dev/sda";
39 boot.loader.timeout = 0;
40
41 # Don't put old configurations in the GRUB menu. The user has no
42 # way to select them anyway.
43 boot.loader.grub.configurationLimit = 0;
44
45 # Allow root logins only using the SSH key that the user specified
46 # at instance creation time.
47 services.openssh.enable = true;
48 services.openssh.permitRootLogin = "prohibit-password";
49 services.openssh.passwordAuthentication = mkDefault false;
50
51 # Use GCE udev rules for dynamic disk volumes
52 services.udev.packages = [ gce ];
53
54 # Force getting the hostname from Google Compute.
55 networking.hostName = mkDefault "";
56
57 # Always include cryptsetup so that NixOps can use it.
58 environment.systemPackages = [ pkgs.cryptsetup ];
59
60 # Rely on GCP's firewall instead
61 networking.firewall.enable = mkDefault false;
62
63 # Configure default metadata hostnames
64 networking.extraHosts = ''
65 169.254.169.254 metadata.google.internal metadata
66 '';
67
68 networking.timeServers = [ "metadata.google.internal" ];
69
70 networking.usePredictableInterfaceNames = false;
71
72 # allow the google-accounts-daemon to manage users
73 users.mutableUsers = true;
74 # and allow users to sudo without password
75 security.sudo.enable = true;
76 security.sudo.extraConfig = ''
77 %google-sudoers ALL=(ALL:ALL) NOPASSWD:ALL
78 '';
79
80 # NOTE: google-accounts tries to write to /etc/sudoers.d but the folder doesn't exist
81 # FIXME: not such file or directory on dynamic SSH provisioning
82 systemd.services.google-accounts-daemon = {
83 description = "Google Compute Engine Accounts Daemon";
84 # This daemon creates dynamic users
85 enable = config.users.mutableUsers;
86 after = [
87 "network.target"
88 "google-instance-setup.service"
89 "google-network-setup.service"
90 ];
91 wantedBy = [ "multi-user.target" ];
92 requires = ["network.target"];
93 path = with pkgs; [ shadow ];
94 serviceConfig = {
95 Type = "simple";
96 ExecStart = "${gce}/bin/google_accounts_daemon --debug";
97 };
98 };
99
100 systemd.services.google-clock-skew-daemon = {
101 description = "Google Compute Engine Clock Skew Daemon";
102 after = [
103 "network.target"
104 "google-instance-setup.service"
105 "google-network-setup.service"
106 ];
107 requires = [ "network.target" ];
108 wantedBy = [ "multi-user.target" ];
109 serviceConfig = {
110 Type = "simple";
111 ExecStart = "${gce}/bin/google_clock_skew_daemon --debug";
112 };
113 };
114
115 systemd.services.google-instance-setup = {
116 description = "Google Compute Engine Instance Setup";
117 after = ["fs.target" "network-online.target" "network.target" "rsyslog.service"];
118 before = ["sshd.service"];
119 wants = ["local-fs.target" "network-online.target" "network.target"];
120 wantedBy = [ "sshd.service" "multi-user.target" ];
121 path = with pkgs; [ ethtool openssh ];
122 serviceConfig = {
123 ExecStart = "${gce}/bin/google_instance_setup --debug";
124 Type = "oneshot";
125 };
126 };
127
128 systemd.services.google-ip-forwarding-daemon = {
129 description = "Google Compute Engine IP Forwarding Daemon";
130 after = ["network.target" "google-instance-setup.service" "google-network-setup.service"];
131 requires = ["network.target"];
132 wantedBy = [ "multi-user.target" ];
133 path = with pkgs; [ iproute ];
134 serviceConfig = {
135 Type = "simple";
136 ExecStart = "${gce}/bin/google_ip_forwarding_daemon --debug";
137 };
138 };
139
140 systemd.services.google-shutdown-scripts = {
141 description = "Google Compute Engine Shutdown Scripts";
142 after = [
143 "local-fs.target"
144 "network-online.target"
145 "network.target"
146 "rsyslog.service"
147 "google-instance-setup.service"
148 "google-network-setup.service"
149 ];
150 wants = [ "local-fs.target" "network-online.target" "network.target"];
151 wantedBy = [ "multi-user.target" ];
152 serviceConfig = {
153 ExecStart = "${pkgs.coreutils}/bin/true";
154 ExecStop = "${gce}/bin/google_metadata_script_runner --debug --script-type shutdown";
155 Type = "oneshot";
156 RemainAfterExit = true;
157 TimeoutStopSec = 0;
158 };
159 };
160
161 systemd.services.google-network-setup = {
162 description = "Google Compute Engine Network Setup";
163 after = [
164 "local-fs.target"
165 "network-online.target"
166 "network.target"
167 "rsyslog.service"
168 ];
169 wants = [ "local-fs.target" "network-online.target" "network.target"];
170 wantedBy = [ "multi-user.target" ];
171 serviceConfig = {
172 ExecStart = "${gce}/bin/google_network_setup --debug";
173 KillMode = "process";
174 Type = "oneshot";
175 };
176 };
177
178 systemd.services.google-startup-scripts = {
179 description = "Google Compute Engine Startup Scripts";
180 after = [
181 "local-fs.target"
182 "network-online.target"
183 "network.target"
184 "rsyslog.service"
185 "google-instance-setup.service"
186 "google-network-setup.service"
187 ];
188 wants = [ "local-fs.target" "network-online.target" "network.target"];
189 wantedBy = [ "multi-user.target" ];
190 serviceConfig = {
191 ExecStart = "${gce}/bin/google_metadata_script_runner --debug --script-type startup";
192 KillMode = "process";
193 Type = "oneshot";
194 };
195 };
196
197 # TODO: remove this
198 systemd.services.fetch-ssh-keys =
199 { description = "Fetch host keys and authorized_keys for root user";
200
201 wantedBy = [ "sshd.service" ];
202 before = [ "sshd.service" ];
203 after = [ "network-online.target" ];
204 wants = [ "network-online.target" ];
205
206 script = let wget = "${pkgs.wget}/bin/wget --retry-connrefused -t 15 --waitretry=10 --header='Metadata-Flavor: Google'";
207 mktemp = "mktemp --tmpdir=/run"; in
208 ''
209 # When dealing with cryptographic keys, we want to keep things private.
210 umask 077
211 # Don't download the SSH key if it has already been downloaded
212 echo "Obtaining SSH keys..."
213 mkdir -m 0700 -p /root/.ssh
214 AUTH_KEYS=$(${mktemp})
215 ${wget} -O $AUTH_KEYS --header="Metadata-Flavor: Google" http://metadata.google.internal/computeMetadata/v1/instance/attributes/sshKeys
216 if [ -s $AUTH_KEYS ]; then
217
218 # Read in key one by one, split in case Google decided
219 # to append metadata (it does sometimes) and add to
220 # authorized_keys if not already present.
221 touch /root/.ssh/authorized_keys
222 NEW_KEYS=$(${mktemp})
223 # Yes this is a nix escape of two single quotes.
224 while IFS=''' read -r line || [[ -n "$line" ]]; do
225 keyLine=$(echo -n "$line" | cut -d ':' -f2)
226 IFS=' ' read -r -a array <<< "$keyLine"
227 if [ ''${#array[@]} -ge 3 ]; then
228 echo ''${array[@]:0:3} >> $NEW_KEYS
229 echo "Added ''${array[@]:2} to authorized_keys"
230 fi
231 done < $AUTH_KEYS
232 mv $NEW_KEYS /root/.ssh/authorized_keys
233 chmod 600 /root/.ssh/authorized_keys
234 rm -f $KEY_PUB
235 else
236 echo "Downloading http://metadata.google.internal/computeMetadata/v1/project/attributes/sshKeys failed."
237 false
238 fi
239 rm -f $AUTH_KEYS
240 '';
241 serviceConfig.Type = "oneshot";
242 serviceConfig.RemainAfterExit = true;
243 serviceConfig.StandardError = "journal+console";
244 serviceConfig.StandardOutput = "journal+console";
245 };
246
247 # Settings taken from https://github.com/GoogleCloudPlatform/compute-image-packages/blob/master/google_config/sysctl/11-gce-network-security.conf
248 boot.kernel.sysctl = {
249 # Turn on SYN-flood protections. Starting with 2.6.26, there is no loss
250 # of TCP functionality/features under normal conditions. When flood
251 # protections kick in under high unanswered-SYN load, the system
252 # should remain more stable, with a trade off of some loss of TCP
253 # functionality/features (e.g. TCP Window scaling).
254 "net.ipv4.tcp_syncookies" = mkDefault "1";
255
256 # ignores source-routed packets
257 "net.ipv4.conf.all.accept_source_route" = mkDefault "0";
258
259 # ignores source-routed packets
260 "net.ipv4.conf.default.accept_source_route" = mkDefault "0";
261
262 # ignores ICMP redirects
263 "net.ipv4.conf.all.accept_redirects" = mkDefault "0";
264
265 # ignores ICMP redirects
266 "net.ipv4.conf.default.accept_redirects" = mkDefault "0";
267
268 # ignores ICMP redirects from non-GW hosts
269 "net.ipv4.conf.all.secure_redirects" = mkDefault "1";
270
271 # ignores ICMP redirects from non-GW hosts
272 "net.ipv4.conf.default.secure_redirects" = mkDefault "1";
273
274 # don't allow traffic between networks or act as a router
275 "net.ipv4.ip_forward" = mkDefault "0";
276
277 # don't allow traffic between networks or act as a router
278 "net.ipv4.conf.all.send_redirects" = mkDefault "0";
279
280 # don't allow traffic between networks or act as a router
281 "net.ipv4.conf.default.send_redirects" = mkDefault "0";
282
283 # reverse path filtering - IP spoofing protection
284 "net.ipv4.conf.all.rp_filter" = mkDefault "1";
285
286 # reverse path filtering - IP spoofing protection
287 "net.ipv4.conf.default.rp_filter" = mkDefault "1";
288
289 # ignores ICMP broadcasts to avoid participating in Smurf attacks
290 "net.ipv4.icmp_echo_ignore_broadcasts" = mkDefault "1";
291
292 # ignores bad ICMP errors
293 "net.ipv4.icmp_ignore_bogus_error_responses" = mkDefault "1";
294
295 # logs spoofed, source-routed, and redirect packets
296 "net.ipv4.conf.all.log_martians" = mkDefault "1";
297
298 # log spoofed, source-routed, and redirect packets
299 "net.ipv4.conf.default.log_martians" = mkDefault "1";
300
301 # implements RFC 1337 fix
302 "net.ipv4.tcp_rfc1337" = mkDefault "1";
303
304 # randomizes addresses of mmap base, heap, stack and VDSO page
305 "kernel.randomize_va_space" = mkDefault "2";
306
307 # Reboot the machine soon after a kernel panic.
308 "kernel.panic" = mkDefault "10";
309
310 ## Not part of the original config
311
312 # provides protection from ToCToU races
313 "fs.protected_hardlinks" = mkDefault "1";
314
315 # provides protection from ToCToU races
316 "fs.protected_symlinks" = mkDefault "1";
317
318 # makes locating kernel addresses more difficult
319 "kernel.kptr_restrict" = mkDefault "1";
320
321 # set ptrace protections
322 "kernel.yama.ptrace_scope" = mkOverride 500 "1";
323
324 # set perf only available to root
325 "kernel.perf_event_paranoid" = mkDefault "2";
326
327 };
328
329}