nixpkgs/nixos/modules/system/boot/initrd-ssh.nix

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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.boot.initrd.network.ssh;
in
{
options = {
boot.initrd.network.ssh.enable = mkOption {
type = types.bool;
default = false;
description = ''
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.
'';
};
boot.initrd.network.ssh.port = mkOption {
type = types.int;
default = 22;
description = ''
Port on which SSH initrd service should listen.
'';
};
boot.initrd.network.ssh.shell = mkOption {
type = types.str;
default = "/bin/ash";
description = ''
Login shell of the remote user. Can be used to limit actions user can do.
'';
};
boot.initrd.network.ssh.hostRSAKey = mkOption {
type = types.nullOr types.path;
default = null;
description = ''
RSA SSH private key file in the Dropbear format.
WARNING: This key is contained 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!
'';
};
boot.initrd.network.ssh.hostDSSKey = mkOption {
type = types.nullOr types.path;
default = null;
description = ''
DSS SSH private key file in the Dropbear format.
WARNING: This key is contained 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!
'';
};
boot.initrd.network.ssh.hostECDSAKey = mkOption {
type = types.nullOr types.path;
default = null;
description = ''
ECDSA SSH private key file in the Dropbear format.
WARNING: This key is contained 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!
'';
};
boot.initrd.network.ssh.authorizedKeys = mkOption {
type = types.listOf types.str;
default = config.users.extraUsers.root.openssh.authorizedKeys.keys;
description = ''
Authorized keys for the root user on initrd.
'';
};
};
config = mkIf (config.boot.initrd.network.enable && cfg.enable) {
assertions = [
{ assertion = cfg.hostRSAKey != null || cfg.hostDSSKey != null || cfg.hostECDSAKey != null;
message = "You should specify at least one host key for initrd SSH";
}
{ assertion = cfg.authorizedKeys != [];
message = "You should specify at least one authorized key for initrd SSH";
}
];
boot.initrd.extraUtilsCommands = ''
copy_bin_and_libs ${pkgs.dropbear}/bin/dropbear
2016-05-07 14:38:34 +02:00
cp -pv ${pkgs.glibc.out}/lib/libnss_files.so.* $out/lib
${optionalString (cfg.hostRSAKey != null) "install -D ${cfg.hostRSAKey} $out/etc/dropbear/dropbear_rsa_host_key"}
${optionalString (cfg.hostDSSKey != null) "install -D ${cfg.hostDSSKey} $out/etc/dropbear/dropbear_dss_host_key"}
${optionalString (cfg.hostECDSAKey != null) "install -D ${cfg.hostECDSAKey} $out/etc/dropbear/dropbear_ecdsa_host_key"}
'';
boot.initrd.extraUtilsCommandsTest = ''
$out/bin/dropbear -V
'';
boot.initrd.network.postCommands = ''
echo '${cfg.shell}' > /etc/shells
echo 'root:x:0:0:root:/root:${cfg.shell}' > /etc/passwd
echo 'passwd: files' > /etc/nsswitch.conf
mkdir -p /var/log
touch /var/log/lastlog
mkdir -p /etc/dropbear
${optionalString (cfg.hostRSAKey != null) "ln -s $extraUtils/etc/dropbear/dropbear_rsa_host_key /etc/dropbear/dropbear_rsa_host_key"}
${optionalString (cfg.hostDSSKey != null) "ln -s $extraUtils/etc/dropbear/dropbear_dss_host_key /etc/dropbear/dropbear_dss_host_key"}
${optionalString (cfg.hostECDSAKey != null) "ln -s $extraUtils/etc/dropbear/dropbear_ecdsa_host_key /etc/dropbear/dropbear_ecdsa_host_key"}
mkdir -p /root/.ssh
${concatStrings (map (key: ''
echo ${escapeShellArg key} >> /root/.ssh/authorized_keys
'') cfg.authorizedKeys)}
dropbear -s -j -k -E -m -p ${toString cfg.port}
'';
};
}