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use std::{fmt, fs, io::{stdin, IsTerminal}};
use log::info;
use bch_bindgen::bcachefs::bch_sb_handle;
use clap::builder::PossibleValue;
use crate::c_str;
use anyhow::anyhow;
#[derive(Clone, Debug)]
pub enum KeyPolicy {
None,
Fail,
Wait,
Ask,
}
impl std::str::FromStr for KeyPolicy {
type Err = anyhow::Error;
fn from_str(s: &str) -> anyhow::Result<Self> {
match s {
""|"none" => Ok(KeyPolicy::None),
"fail" => Ok(KeyPolicy::Fail),
"wait" => Ok(KeyPolicy::Wait),
"ask" => Ok(KeyPolicy::Ask),
_ => Err(anyhow!("Invalid key policy provided")),
}
}
}
impl clap::ValueEnum for KeyPolicy {
fn value_variants<'a>() -> &'a [Self] {
&[
KeyPolicy::None,
KeyPolicy::Fail,
KeyPolicy::Wait,
KeyPolicy::Ask,
]
}
fn to_possible_value(&self) -> Option<PossibleValue> {
Some(match self {
Self::None => PossibleValue::new("none").alias(""),
Self::Fail => PossibleValue::new("fail"),
Self::Wait => PossibleValue::new("wait"),
Self::Ask => PossibleValue::new("ask"),
})
}
}
impl fmt::Display for KeyPolicy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
KeyPolicy::None => write!(f, "None"),
KeyPolicy::Fail => write!(f, "Fail"),
KeyPolicy::Wait => write!(f, "Wait"),
KeyPolicy::Ask => write!(f, "Ask"),
}
}
}
fn check_for_key(key_name: &std::ffi::CStr) -> anyhow::Result<bool> {
use bch_bindgen::keyutils::{self, keyctl_search};
let key_name = key_name.to_bytes_with_nul().as_ptr() as *const _;
let key_type = c_str!("user");
let key_id = unsafe { keyctl_search(keyutils::KEY_SPEC_USER_KEYRING, key_type, key_name, 0) };
if key_id > 0 {
info!("Key has become available");
Ok(true)
} else {
match errno::errno().0 {
libc::ENOKEY | libc::EKEYREVOKED => Ok(false),
_ => Err(crate::ErrnoError(errno::errno()).into()),
}
}
}
fn wait_for_key(uuid: &uuid::Uuid) -> anyhow::Result<()> {
let key_name = std::ffi::CString::new(format!("bcachefs:{}", uuid)).unwrap();
loop {
if check_for_key(&key_name)? {
break Ok(());
}
std::thread::sleep(std::time::Duration::from_secs(1));
}
}
fn ask_for_key(sb: &bch_sb_handle) -> anyhow::Result<()> {
let pass = if stdin().is_terminal() {
rpassword::prompt_password("Enter passphrase: ")?
} else {
let mut line = String::new();
stdin().read_line(&mut line)?;
line
};
decrypt_master_key(sb, pass)
}
const BCH_KEY_MAGIC: &str = "bch**key";
fn decrypt_master_key(sb: &bch_sb_handle, pass: String) -> anyhow::Result<()> {
use bch_bindgen::bcachefs::{self, bch2_chacha_encrypt_key, bch_encrypted_key, bch_key};
use byteorder::{LittleEndian, ReadBytesExt};
use std::os::raw::c_char;
let key_name = std::ffi::CString::new(format!("bcachefs:{}", sb.sb().uuid())).unwrap();
if check_for_key(&key_name)? {
return Ok(());
}
let bch_key_magic = BCH_KEY_MAGIC.as_bytes().read_u64::<LittleEndian>().unwrap();
let crypt = sb.sb().crypt().unwrap();
let pass = std::ffi::CString::new(pass.trim_end())?; // bind to keep the CString alive
let mut output: bch_key = unsafe {
bcachefs::derive_passphrase(
crypt as *const _ as *mut _,
pass.as_c_str().to_bytes_with_nul().as_ptr() as *const _,
)
};
let mut key = crypt.key().clone();
let ret = unsafe {
bch2_chacha_encrypt_key(
&mut output as *mut _,
sb.sb().nonce(),
&mut key as *mut _ as *mut _,
std::mem::size_of::<bch_encrypted_key>() as usize,
)
};
if ret != 0 {
Err(anyhow!("chacha decryption failure"))
} else if key.magic != bch_key_magic {
Err(anyhow!("failed to verify the password"))
} else {
let key_type = c_str!("user");
let ret = unsafe {
bch_bindgen::keyutils::add_key(
key_type,
key_name.as_c_str().to_bytes_with_nul() as *const _ as *const c_char,
&output as *const _ as *const _,
std::mem::size_of::<bch_key>() as usize,
bch_bindgen::keyutils::KEY_SPEC_USER_KEYRING,
)
};
if ret == -1 {
Err(anyhow!("failed to add key to keyring: {}", errno::errno()))
} else {
Ok(())
}
}
}
pub fn read_from_key_file(block_device: &bch_sb_handle, key_file: &std::path::Path) -> anyhow::Result<()> {
// Attempts to decrypt the master key by key_file
// Return true if decryption was successful, false otherwise
info!("Attempting to decrypt master key for filesystem {}, using key file {}", block_device.sb().uuid(), key_file.display());
// Read the contents of the key file into a string
let pass = fs::read_to_string(key_file)?;
// Call decrypt_master_key with the read string
decrypt_master_key(block_device, pass)
}
pub fn prepare_key(block_device: &bch_sb_handle, password_policy: KeyPolicy) -> anyhow::Result<()> {
info!("Attempting to decrypt master key for filesystem {}, using key policy {}", block_device.sb().uuid(), password_policy);
match password_policy {
KeyPolicy::Fail => Err(anyhow!("no key available")),
KeyPolicy::Wait => Ok(wait_for_key(&block_device.sb().uuid())?),
KeyPolicy::Ask => ask_for_key(block_device),
_ => Err(anyhow!("no keyoption specified for locked filesystem")),
}
}
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