mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-12-01 03:12:51 +00:00
267 lines
8.5 KiB
Nix
267 lines
8.5 KiB
Nix
{ config, lib, pkgs, ... }:
|
|
|
|
with lib;
|
|
|
|
let
|
|
|
|
cfg = config.boot.initrd.network.ssh;
|
|
shell = if cfg.shell == null then "/bin/ash" else cfg.shell;
|
|
inherit (config.programs.ssh) package;
|
|
|
|
enabled = let initrd = config.boot.initrd; in (initrd.network.enable || initrd.systemd.network.enable) && cfg.enable;
|
|
|
|
in
|
|
|
|
{
|
|
|
|
options.boot.initrd.network.ssh = {
|
|
enable = mkOption {
|
|
type = types.bool;
|
|
default = false;
|
|
description = lib.mdDoc ''
|
|
Start SSH service during initrd boot. It can be used to debug failing
|
|
boot on a remote server, enter pasphrase for an encrypted partition etc.
|
|
Service is killed when stage-1 boot is finished.
|
|
|
|
The sshd configuration is largely inherited from
|
|
{option}`services.openssh`.
|
|
'';
|
|
};
|
|
|
|
port = mkOption {
|
|
type = types.port;
|
|
default = 22;
|
|
description = lib.mdDoc ''
|
|
Port on which SSH initrd service should listen.
|
|
'';
|
|
};
|
|
|
|
shell = mkOption {
|
|
type = types.nullOr types.str;
|
|
default = null;
|
|
defaultText = ''"/bin/ash"'';
|
|
description = lib.mdDoc ''
|
|
Login shell of the remote user. Can be used to limit actions user can do.
|
|
'';
|
|
};
|
|
|
|
hostKeys = mkOption {
|
|
type = types.listOf (types.either types.str types.path);
|
|
default = [];
|
|
example = [
|
|
"/etc/secrets/initrd/ssh_host_rsa_key"
|
|
"/etc/secrets/initrd/ssh_host_ed25519_key"
|
|
];
|
|
description = lib.mdDoc ''
|
|
Specify SSH host keys to import into the initrd.
|
|
|
|
To generate keys, use
|
|
{manpage}`ssh-keygen(1)`
|
|
as root:
|
|
|
|
```
|
|
ssh-keygen -t rsa -N "" -f /etc/secrets/initrd/ssh_host_rsa_key
|
|
ssh-keygen -t ed25519 -N "" -f /etc/secrets/initrd/ssh_host_ed25519_key
|
|
```
|
|
|
|
::: {.warning}
|
|
Unless your bootloader supports initrd secrets, these keys
|
|
are stored insecurely in the global Nix store. Do NOT use
|
|
your regular SSH host private keys for this purpose or
|
|
you'll expose them to regular users!
|
|
|
|
Additionally, even if your initrd supports secrets, if
|
|
you're using initrd SSH to unlock an encrypted disk then
|
|
using your regular host keys exposes the private keys on
|
|
your unencrypted boot partition.
|
|
:::
|
|
'';
|
|
};
|
|
|
|
ignoreEmptyHostKeys = mkOption {
|
|
type = types.bool;
|
|
default = false;
|
|
description = lib.mdDoc ''
|
|
Allow leaving {option}`config.boot.initrd.network.ssh` empty,
|
|
to deploy ssh host keys out of band.
|
|
'';
|
|
};
|
|
|
|
authorizedKeys = mkOption {
|
|
type = types.listOf types.str;
|
|
default = config.users.users.root.openssh.authorizedKeys.keys;
|
|
defaultText = literalExpression "config.users.users.root.openssh.authorizedKeys.keys";
|
|
description = lib.mdDoc ''
|
|
Authorized keys for the root user on initrd.
|
|
'';
|
|
};
|
|
|
|
extraConfig = mkOption {
|
|
type = types.lines;
|
|
default = "";
|
|
description = lib.mdDoc "Verbatim contents of {file}`sshd_config`.";
|
|
};
|
|
};
|
|
|
|
imports =
|
|
map (opt: mkRemovedOptionModule ([ "boot" "initrd" "network" "ssh" ] ++ [ opt ]) ''
|
|
The initrd SSH functionality now uses OpenSSH rather than Dropbear.
|
|
|
|
If you want to keep your existing initrd SSH host keys, convert them with
|
|
$ dropbearconvert dropbear openssh dropbear_host_$type_key ssh_host_$type_key
|
|
and then set options.boot.initrd.network.ssh.hostKeys.
|
|
'') [ "hostRSAKey" "hostDSSKey" "hostECDSAKey" ];
|
|
|
|
config = let
|
|
# Nix complains if you include a store hash in initrd path names, so
|
|
# as an awful hack we drop the first character of the hash.
|
|
initrdKeyPath = path: if isString path
|
|
then path
|
|
else let name = builtins.baseNameOf path; in
|
|
builtins.unsafeDiscardStringContext ("/etc/ssh/" +
|
|
substring 1 (stringLength name) name);
|
|
|
|
sshdCfg = config.services.openssh;
|
|
|
|
sshdConfig = ''
|
|
UsePAM no
|
|
Port ${toString cfg.port}
|
|
|
|
PasswordAuthentication no
|
|
AuthorizedKeysFile %h/.ssh/authorized_keys %h/.ssh/authorized_keys2 /etc/ssh/authorized_keys.d/%u
|
|
ChallengeResponseAuthentication no
|
|
|
|
${flip concatMapStrings cfg.hostKeys (path: ''
|
|
HostKey ${initrdKeyPath path}
|
|
'')}
|
|
|
|
KexAlgorithms ${concatStringsSep "," sshdCfg.settings.KexAlgorithms}
|
|
Ciphers ${concatStringsSep "," sshdCfg.settings.Ciphers}
|
|
MACs ${concatStringsSep "," sshdCfg.settings.Macs}
|
|
|
|
LogLevel ${sshdCfg.settings.LogLevel}
|
|
|
|
${if sshdCfg.settings.UseDns then ''
|
|
UseDNS yes
|
|
'' else ''
|
|
UseDNS no
|
|
''}
|
|
|
|
${cfg.extraConfig}
|
|
'';
|
|
in mkIf enabled {
|
|
assertions = [
|
|
{
|
|
assertion = cfg.authorizedKeys != [];
|
|
message = "You should specify at least one authorized key for initrd SSH";
|
|
}
|
|
|
|
{
|
|
assertion = (cfg.hostKeys != []) || cfg.ignoreEmptyHostKeys;
|
|
message = ''
|
|
You must now pre-generate the host keys for initrd SSH.
|
|
See the boot.initrd.network.ssh.hostKeys documentation
|
|
for instructions.
|
|
'';
|
|
}
|
|
|
|
{
|
|
assertion = config.boot.initrd.systemd.enable -> cfg.shell == null;
|
|
message = "systemd stage 1 does not support boot.initrd.network.ssh.shell";
|
|
}
|
|
];
|
|
|
|
boot.initrd.extraUtilsCommands = mkIf (!config.boot.initrd.systemd.enable) ''
|
|
copy_bin_and_libs ${package}/bin/sshd
|
|
cp -pv ${pkgs.glibc.out}/lib/libnss_files.so.* $out/lib
|
|
'';
|
|
|
|
boot.initrd.extraUtilsCommandsTest = mkIf (!config.boot.initrd.systemd.enable) ''
|
|
# sshd requires a host key to check config, so we pass in the test's
|
|
tmpkey="$(mktemp initrd-ssh-testkey.XXXXXXXXXX)"
|
|
cp "${../../../tests/initrd-network-ssh/ssh_host_ed25519_key}" "$tmpkey"
|
|
# keys from Nix store are world-readable, which sshd doesn't like
|
|
chmod 600 "$tmpkey"
|
|
echo -n ${escapeShellArg sshdConfig} |
|
|
$out/bin/sshd -t -f /dev/stdin \
|
|
-h "$tmpkey"
|
|
rm "$tmpkey"
|
|
'';
|
|
|
|
boot.initrd.network.postCommands = mkIf (!config.boot.initrd.systemd.enable) ''
|
|
echo '${shell}' > /etc/shells
|
|
echo 'root:x:0:0:root:/root:${shell}' > /etc/passwd
|
|
echo 'sshd:x:1:1:sshd:/var/empty:/bin/nologin' >> /etc/passwd
|
|
echo 'passwd: files' > /etc/nsswitch.conf
|
|
|
|
mkdir -p /var/log /var/empty
|
|
touch /var/log/lastlog
|
|
|
|
mkdir -p /etc/ssh
|
|
echo -n ${escapeShellArg sshdConfig} > /etc/ssh/sshd_config
|
|
|
|
echo "export PATH=$PATH" >> /etc/profile
|
|
echo "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH" >> /etc/profile
|
|
|
|
mkdir -p /root/.ssh
|
|
${concatStrings (map (key: ''
|
|
echo ${escapeShellArg key} >> /root/.ssh/authorized_keys
|
|
'') cfg.authorizedKeys)}
|
|
|
|
${flip concatMapStrings cfg.hostKeys (path: ''
|
|
# keys from Nix store are world-readable, which sshd doesn't like
|
|
chmod 0600 "${initrdKeyPath path}"
|
|
'')}
|
|
|
|
/bin/sshd -e
|
|
'';
|
|
|
|
boot.initrd.postMountCommands = mkIf (!config.boot.initrd.systemd.enable) ''
|
|
# Stop sshd cleanly before stage 2.
|
|
#
|
|
# If you want to keep it around to debug post-mount SSH issues,
|
|
# run `touch /.keep_sshd` (either from an SSH session or in
|
|
# another initrd hook like preDeviceCommands).
|
|
if ! [ -e /.keep_sshd ]; then
|
|
pkill -x sshd
|
|
fi
|
|
'';
|
|
|
|
boot.initrd.secrets = listToAttrs
|
|
(map (path: nameValuePair (initrdKeyPath path) path) cfg.hostKeys);
|
|
|
|
# Systemd initrd stuff
|
|
boot.initrd.systemd = mkIf config.boot.initrd.systemd.enable {
|
|
users.sshd = { uid = 1; group = "sshd"; };
|
|
groups.sshd = { gid = 1; };
|
|
|
|
contents."/etc/ssh/authorized_keys.d/root".text =
|
|
concatStringsSep "\n" config.boot.initrd.network.ssh.authorizedKeys;
|
|
contents."/etc/ssh/sshd_config".text = sshdConfig;
|
|
storePaths = ["${package}/bin/sshd"];
|
|
|
|
services.sshd = {
|
|
description = "SSH Daemon";
|
|
wantedBy = ["initrd.target"];
|
|
after = ["network.target" "initrd-nixos-copy-secrets.service"];
|
|
|
|
# Keys from Nix store are world-readable, which sshd doesn't
|
|
# like. If this were a real nix store and not the initrd, we
|
|
# neither would nor could do this
|
|
preStart = flip concatMapStrings cfg.hostKeys (path: ''
|
|
/bin/chmod 0600 "${initrdKeyPath path}"
|
|
'');
|
|
unitConfig.DefaultDependencies = false;
|
|
serviceConfig = {
|
|
ExecStart = "${package}/bin/sshd -D -f /etc/ssh/sshd_config";
|
|
Type = "simple";
|
|
KillMode = "process";
|
|
Restart = "on-failure";
|
|
};
|
|
};
|
|
};
|
|
|
|
};
|
|
|
|
}
|