.drone.yml

@@ -12,7 +12,7 @@ steps:
    environment:
     DEBIAN_FRONTEND: noninteractive
    commands:
-    - apt update && apt install -y cargo libkeyutils-dev libclang-dev clang pkg-config libcryptsetup-dev 
+    - apt update && apt install -y cargo libkeyutils-dev libclang-dev clang pkg-config libcryptsetup-dev libpam-dev 
     - cargo test --locked
  - name: publish
    image: ubuntu:focal
@@ -22,7 +22,7 @@ steps:
      from_secret: cargo_tkn
    commands:
     - grep -E 'version ?= ?"${DRONE_TAG}"' -i Cargo.toml || (printf "incorrect crate/tag version" && exit 1)
-    - apt update && apt install -y cargo libkeyutils-dev libclang-dev clang pkg-config libcryptsetup-dev 
+    - apt update && apt install -y cargo libkeyutils-dev libclang-dev clang pkg-config libcryptsetup-dev libpam-dev
     - cargo package --all-features
     - cargo publish --all-features
    when:

Cargo.lock

@@ -377,18 +377,20 @@ dependencies = [
 
 [[package]]
 name = "fido2luks"
-version = "0.2.14"
+version = "0.2.15"
 dependencies = [
  "ctap_hmac",
  "failure",
  "hex",
  "libcryptsetup-rs",
+ "pamsm",
  "ring",
  "rpassword",
  "serde",
  "serde_derive",
  "serde_json",
  "structopt",
+ "sudo",
 ]
 
 [[package]]
@@ -596,6 +598,12 @@ version = "0.20.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ab52be62400ca80aa00285d25253d7f7c437b7375c4de678f5405d3afe82ca5"
 
+[[package]]
+name = "pamsm"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3580ed2ebe075c74db583233318abf4b07bc8d9a40c7691d0ae9c186e19e43dd"
+
 [[package]]
 name = "peeking_take_while"
 version = "0.1.2"
@@ -980,6 +988,16 @@ dependencies = [
  "syn 1.0.40",
 ]
 
+[[package]]
+name = "sudo"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a88e74edf206f281aff2820aa2066c781331044c770626dcafe19491f214e05"
+dependencies = [
+ "libc",
+ "log",
+]
+
 [[package]]
 name = "syn"
 version = "0.15.44"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fido2luks"
-version = "0.2.14"
+version = "0.2.15"
 authors = ["shimunn <shimun@shimun.net>"]
 edition = "2018"
 
@@ -24,6 +24,8 @@ libcryptsetup-rs = "0.4.1"
 serde_json = "1.0.51"
 serde_derive = "1.0.106"
 serde = "1.0.106"
+pamsm = { version = "0.4.1", features = ["libpam"] }
+sudo = "0.5.0"
 
 [build-dependencies]
 ctap_hmac = { version="0.4.2", features = ["request_multiple"] }
@@ -32,6 +34,7 @@ ring = "0.13.5"
 failure = "0.1.5"
 rpassword = "4.0.1"
 libcryptsetup-rs = "0.4.1"
+pamsm = { version = "0.4.1", features = ["libpam"] }
 structopt = "0.3.2"
 
 [profile.release]
@@ -41,12 +44,22 @@ panic = 'abort'
 incremental = false
 overflow-checks = false
 
+[[bin]]
+name = "fido2luks"
+path = "src/main.rs"
+
+[lib]
+name = "fido2luks_pam"
+path = "src/lib.rs"
+crate-type = ["cdylib"]
+
 [package.metadata.deb]
 depends = "$auto, cryptsetup"
-build-depends = "libclang-dev, libcryptsetup-dev"
+build-depends = "libclang-dev, libcryptsetup-dev, libpam-dev"
 extended-description = "Decrypt your LUKS partition using a FIDO2 compatible authenticator"
 assets = [
     ["target/release/fido2luks", "usr/bin/", "755"],
+    ["target/release/libfido2luks_pam.so", "usr/lib/x86_64-linux-gnu/security/pam_fido2luks.so", "755"],
     ["fido2luks.bash", "usr/share/bash-completion/completions/fido2luks", "644"],
     ["initramfs-tools/keyscript.sh", "/lib/cryptsetup/scripts/fido2luks", "755" ],
     ["initramfs-tools/hook/fido2luks.sh", "etc/initramfs-tools/hooks/", "755" ],

src/cli_args/config.rs

@@ -198,7 +198,7 @@ mod test {
     fn input_salt_obtain() {
         assert_eq!(
             SecretInput::String("abc".into())
-                .obtain(&PasswordHelper::Stdin)
+                .obtain_sha256(&PasswordHelper::Stdin)
                 .unwrap(),
             [
                 186, 120, 22, 191, 143, 1, 207, 234, 65, 65, 64, 222, 93, 174, 34, 35, 176, 3, 97,

src/error.rs

@@ -1,10 +1,10 @@
 use ctap::FidoError;
 use libcryptsetup_rs::LibcryptErr;
+use pamsm::PamError;
 use std::io;
 use std::io::ErrorKind;
 use std::string::FromUtf8Error;
 use Fido2LuksError::*;
-
 pub type Fido2LuksResult<T> = Result<T, Fido2LuksError>;
 
 #[derive(Debug, Fail)]
@@ -29,6 +29,10 @@ pub enum Fido2LuksError {
     WrongSecret,
     #[fail(display = "not an utf8 string")]
     StringEncodingError { cause: FromUtf8Error },
+    #[fail(display = "elevated privileges required")]
+    MissingPrivileges,
+    #[fail(display = "{}", cause)]
+    Configuration { cause: ConfigurationError },
 }
 
 impl Fido2LuksError {
@@ -50,6 +54,26 @@ pub enum AskPassError {
     IO(io::Error),
     #[fail(display = "provided passwords don't match")]
     Mismatch,
+    #[fail(display = "unable to retrieve password: {}", _0)]
+    Pam(PamError),
+}
+
+impl From<PamError> for AskPassError {
+    fn from(e: PamError) -> Self {
+        AskPassError::Pam(e)
+    }
+}
+
+impl From<io::Error> for AskPassError {
+    fn from(e: io::Error) -> Self {
+        AskPassError::IO(e)
+    }
+}
+
+impl From<AskPassError> for Fido2LuksError {
+    fn from(cause: AskPassError) -> Self {
+        Fido2LuksError::AskPassError { cause }
+    }
 }
 
 #[derive(Debug, Fail)]
@@ -112,3 +136,16 @@ impl From<FromUtf8Error> for Fido2LuksError {
         StringEncodingError { cause: e }
     }
 }
+#[derive(Debug, Fail)]
+pub enum ConfigurationError {
+    #[fail(display = "config is missing some values: {:?}", _0)]
+    Missing(Vec<String>),
+    #[fail(display = "config attribute {} contains an invalid value: {}", _1, _0)]
+    InvalidValue(String, String),
+}
+
+impl From<ConfigurationError> for Fido2LuksError {
+    fn from(cause: ConfigurationError) -> Fido2LuksError {
+        Fido2LuksError::Configuration { cause }
+    }
+}

src/lib.rs

@@ -0,0 +1,183 @@
+#[macro_use]
+extern crate failure;
+extern crate ctap_hmac as ctap;
+#[macro_use]
+extern crate serde_derive;
+use crate::cli_args::{CommaSeparated, HexEncoded};
+use crate::device::*;
+use crate::error::*;
+use crate::luks::*;
+use ctap::FidoCredential;
+use failure::_core::time::Duration;
+use pamsm::PamLibExt;
+use pamsm::*;
+use std::collections::{HashMap, HashSet};
+use std::path::Path;
+use std::str::FromStr;
+use sudo::{self, RunningAs};
+
+pub mod cli_args;
+pub mod device;
+pub mod error;
+pub mod luks;
+pub mod util;
+
+struct PamFido2Luks;
+
+impl PamFido2Luks {
+    fn open(
+        &self,
+        user: String,
+        mut password: impl FnMut(&str) -> PamResult<String>,
+        args: Vec<String>,
+    ) -> Fido2LuksResult<()> {
+        let args: HashMap<String, String> = args
+            .into_iter()
+            .filter_map(|arg| {
+                let mut parts = arg.split("=");
+                parts
+                    .by_ref()
+                    .next()
+                    .map(|key| (key.to_string(), parts.collect::<Vec<_>>().join("=")))
+            })
+            .collect();
+
+        let credentials = match args.get("credentials").map(|creds| {
+            <CommaSeparated<String>>::from_str(creds)
+                .map(|cs| cs.0)
+                .map_err(|_| ConfigurationError::InvalidValue("credentials".into(), creds.into()))
+        }) {
+            Some(creds) => creds?,
+            _ => Vec::new(),
+        };
+        let pin = args.get("pin");
+        let pin_prefix = args
+            .get("pin-prefix")
+            .map(|p| p.parse::<bool>().unwrap_or_default())
+            .unwrap_or_default();
+        let device = args
+            .get("device")
+            .map(|device| device.replace("%user%", user.as_str()));
+        let name = args
+            .get("name")
+            .map(|name| name.replace("%user%", user.as_str()));
+
+        let mut attempts = args
+            .get("attempts")
+            .and_then(|a| a.parse::<usize>().ok())
+            .unwrap_or(3);
+
+        if let (Some(device), Some(name)) = (device, name) {
+            if !Path::new(&device).exists() || Path::new(&format!("/dev/mapper/{}", name)).exists()
+            {
+                return Ok(());
+            }
+            // root required to mount luks
+            match sudo::check() {
+                RunningAs::User => return Err(Fido2LuksError::MissingPrivileges),
+                _ => {
+                    sudo::escalate_if_needed().map_err(|_| Fido2LuksError::MissingPrivileges)?;
+                }
+            }
+            let mut device = LuksDevice::load(device)?;
+            let mut additional_credentials: HashSet<String> = HashSet::new();
+            if device.is_luks2()? {
+                for token in device.tokens()? {
+                    let (_, token) = token?;
+                    additional_credentials.extend(token.credential.into_iter());
+                }
+            }
+            let credentials: Vec<FidoCredential> = credentials
+                .into_iter()
+                .chain(additional_credentials.into_iter())
+                .map(|cred| HexEncoded::from_str(cred.as_str()))
+                .map(|cred| FidoCredential {
+                    id: cred.unwrap().0,
+                    public_key: None,
+                })
+                .collect();
+            let credentials: Vec<&FidoCredential> = credentials.iter().collect();
+            if !credentials.is_empty() {
+                loop {
+                    let (pin, pass) = if pin_prefix {
+                        let password = password("PIN + FIDO2 salt (pin:password):")
+                            .map_err(|e| Fido2LuksError::AskPassError { cause: e.into() })?;
+                        let mut parts = password.split(":");
+                        (
+                            parts.next().map(|p| p.to_string()).or(pin.cloned()),
+                            parts.collect::<Vec<_>>().join(":"),
+                        )
+                    } else {
+                        (
+                            pin.cloned(),
+                            password("FIDO2 salt: ")
+                                .map_err(|e| Fido2LuksError::AskPassError { cause: e.into() })?,
+                        )
+                    };
+
+                    let salt = util::sha256(&[pass.as_bytes()]);
+                    let secret = util::sha256(&[
+                        &salt,
+                        &perform_challenge(
+                            &credentials[..],
+                            &salt,
+                            Duration::from_secs(15),
+                            pin.as_ref().map(String::as_str),
+                        )?
+                        .0[..],
+                    ]);
+                    match device.activate(name.as_str(), &secret[..], None) {
+                        Ok(_) => return Ok(()),
+                        _ if attempts > 0 => {
+                            attempts -= 1;
+                            continue;
+                        }
+                        Err(e) => break Err(e),
+                    }
+                }
+            } else {
+                Err(ConfigurationError::Missing(vec!["credentials".into()]).into())
+            }
+        } else {
+            Ok(())
+        }
+    }
+}
+
+impl PamServiceModule for PamFido2Luks {
+    fn authenticate(pamh: Pam, _flag: PamFlag, args: Vec<String>) -> PamError {
+        let perfrom_authenticate = move || -> Fido2LuksResult<()> {
+            let user = match pamh.get_cached_user() {
+                Err(e) => Err(AskPassError::Pam(e))?,
+                Ok(p) => p.map(|s| s.to_str().map(str::to_string).unwrap()),
+            };
+            let mut password = match pamh.get_authtok(None) {
+                Err(e) => Err(AskPassError::Pam(e))?,
+                Ok(p) => p.map(|s| s.to_str().map(str::to_string).unwrap()),
+            };
+            if let Some(user) = user {
+                PamFido2Luks.open(
+                    user,
+                    move |q: &str| match password.take() {
+                        Some(pass) => Ok(pass),
+                        None => pamh
+                            .conv(Some(q), PamMsgStyle::PROMPT_ECHO_OFF)
+                            .map(|s| s.map(|s| s.to_str().unwrap()).unwrap_or("").to_string()),
+                    },
+                    args,
+                )
+            } else {
+                Err(AskPassError::Pam(PamError::AUTH_ERR))?
+            }
+        };
+        match perfrom_authenticate() {
+            Ok(_) => PamError::SUCCESS,
+            Err(e) => {
+                eprintln!("{}", e);
+                PamError::AUTH_ERR
+            }
+        }
+    }
+}
+
+pam_module!(PamFido2Luks);