海运的博客

ubuntu通过dropbear ssh远程解锁luks rootfs全盘加密

发布时间:January 1, 2021 // 分类: LUKS // No Comments

之前使用preseed安装ubuntu luks全盘加密,这样每次重启系统都要通过vnc输入密码,可以将dropbear添加到initramfs,通过ssh解锁要方便很多。
安装dropbear-initramfs:

apt install dropbear-initramfs

安装时会提示:

dropbear: WARNING: Invalid authorized_keys file, remote unlocking of cryptroot via SSH won't work!

因为生成initramfs时要包含/etc/dropbear-initramfs/authorized_keys,复制ssh验证密钥:

#本地执行
ssh-copy-id  root@www.haiyun.me
#远程执行
cp -p ~/.ssh/authorized_keys /etc/dropbear-initramfs/

修改dropbear ssh端口:

echo 'DROPBEAR_OPTIONS="-p 2222"' >> /etc/dropbear-initramfs/config

配置initramfs ip:

#IP="${ip_address}::${gateway_ip}:${netmask}:${optional_fqdn}:${interface_name}:${auto_config}:${name_server}
echo 'IP=192.168.1.2::192.168.1.1:255.255.255.0::eth0:none:1.1.1.1' >> /etc/initramfs-tools/initramfs.conf

ip配置也可添加到grub启动参数:

GRUB_CMDLINE_LINUX="ip=192.168.1.2::192.168.1.1:255.255.255.0::eth0:none:1.1.1.1"

可选修改cryptroot-unlock解锁程序通过参数输入加密密码:

sed -i  '/^set/i if [ ! -n "\$1" ] ; then echo "use cryptroot-unlock password";exit;fi' /usr/share/cryptsetup/initramfs/bin/cryptroot-unlock
sed -i 's/read -rs/#read -rs/' /usr/share/cryptsetup/initramfs/bin/cryptroot-unlock
sed -i 's/\$REPLY/\$1/' /usr/share/cryptsetup/initramfs/bin/cryptroot-unlock

重新生成initramfs:

update-initramfs -u -k all

重启后通过ssh连接执行解锁luks:

cryptroot-unlock password

虽然/usr/share/initramfs-tools/scripts/init-bottom/dropbear有包含解锁luks后删除ip信息,但是启动后还是包含在initramfs内配置的ip信息,使用ubuntu在配置网络前清除ip信息:

sed -i '/iface eth0/a pre-up ip addr flush dev eth0' /etc/network/interfaces

使用php调用expect ssh远程自动解锁luks:

<?php
ini_set("expect.timeout", 5);
ini_set("expect.loguser", "off");
$host = "www.haiyun.me";
$port = 22;
$pass = "xxxxxx";
$stream = expect_popen("ssh -o StrictHostKeyChecking=no -p {$port} root@{$host}");
$cases = array(
  array("password:", "pass"),
  array("Enter 'help'", "shell"),
  array("Please unlock disk", "unlock"),
  array("set up successfully", "sus"),
  array("Permission denied", "den"),
  array("cryptsetup failed", "fai")
);

while (true) {
  switch (expect_expectl($stream, $cases)) {
  case "den":
    echo 'Permission denied'.PHP_EOL;
    break 2;
  case "pass":
    fwrite($stream, "password\n");
    break;
  case "shell":
    fwrite($stream, "/usr/bin/cryptroot-unlock\n");
    //fwrite($stream, "/usr/bin/cryptroot-unlock {$pass}\n");
    break;
  case "unlock":
    fwrite($stream, "{$pass}\n");
    break;
  case "fai":
    echo 'unlock failed, bad password or options?'.PHP_EOL;
    break 2;
  case "sus":
    echo 'unlock sus'.PHP_EOL;
    break 2;
  case EXP_TIMEOUT:
    echo 'timeout'.PHP_EOL;
    break 2;
  case EXP_EOF:
    echo 'eof'.PHP_EOL;
    break 2; 
  default:
    die("Error has occurred!");
  }
}
fclose ($stream);

php调用ssh2扩展远程解锁luks加密:

<?php
$host = 'www.haiyun.me';
$port = 2222;
$pass = 'xxxx';
if (!($conn = ssh2_connect($host, $port, array('hostkey'=>'ssh-rsa')))) {
  die("conn fail\n");
}
//注意路径不要使用~/.ssh/id_rsa.pub,会遇到段错误和其它莫名其妙的问题
if (ssh2_auth_pubkey_file($conn, 'root', '/root/.ssh/id_rsa.pub', '/root/.ssh/id_rsa')) {
  echo "auth sus\n";
} else {
  die("auth fail\n");
}
function expect($stream, $match) {
  $time = time();
  $res = '';
  while(!feof($stream)){
    //if (($buffer = fgets($stream, 4096)) !== false) {
    if (($buffer = fread($stream, 4096)) !== false) {
      $res .= $buffer;
    }
    if (stristr($res, $match)) {
      return 'sus';
    }
    $now = time();
    if (($now - $time) >= 10) {
      return 'timeout';
    }
    usleep(100);
  }
  return 'disconnect';
}
 
$shell=ssh2_shell($conn, 'xterm');
fwrite($shell, "/usr/bin/cryptroot-unlock\n");
$res = expect($shell, 'Please unlock disk');
if ($res == 'sus') {
  fwrite($shell, "{$pass}\n");
  $res = expect($shell, 'set up successfully');
  if ($res == 'sus') {
  }
  var_dump($res);
}

发现的问题:此方法在ubuntu20.04使用编译的4.14内核bbrplus下导致系统启动很慢,5.4及5.10内核测试正常。
另外一种通过dracut生成initramfs调用openssh解锁luks的方法:
https://github.com/gsauthof/dracut-sshd
参考:
https://hamy.io/post/0009/how-to-install-luks-encrypted-ubuntu-18.04.x-server-and-enable-remote-unlocking/

标签:luks, 硬盘加密, 全盘加密, luks加密, ssh解锁luks

评论已关闭

分类
最新文章
最近回复
  • Jimmy: 方法一 nghtp3步骤需要改成如下才能编译成功: git clone https://git...
  • 海运: 地址格式和udpxy一样,udpxy和msd_lite能用这个就能用。
  • 1: 怎么用 编译后的程序在家里路由器内任意一台设备上运行就可以吗?比如笔记本电脑 m参数是笔记本的...
  • 孤狼: ups_status_set: seems that UPS [BK650M2-CH] is ...
  • 孤狼: 擦。。。。apcupsd会失联 nut在冲到到100的时候会ONBATT进入关机状态,我想想办...
  • 海运: 网络,找到相应的url编辑重发请求,firefox有此功能,其它未知。
  • knetxp: 用浏览器F12网络拦截或监听后编辑重发请求,修改url中的set为set_super,将POS...
  • Albert: 啊啊啊啊啊啊啊啊啊 我太激动了,终于好了英文区搜索了半天,翻遍了 pve 论坛没找到好方法,博...
  • jiangker: good, very helpful to me
  • fengfeng: N1 armbian 能有编译下内核吗。。我要开启can 不懂怎么操作