From 63f29249d394ed458654e5116c9ad424df60fd9d Mon Sep 17 00:00:00 2001
From: shimun <shimun@shimun.net>
Date: Fri, 25 Sep 2020 00:23:36 +0200
Subject: [PATCH] pam module

---
 Cargo.lock |   7 ++++
 Cargo.toml |  11 ++++++
 src/lib.rs | 111 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 129 insertions(+)
 create mode 100644 src/lib.rs

diff --git a/Cargo.lock b/Cargo.lock
index b91b404..679ecf0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -383,6 +383,7 @@ dependencies = [
  "failure",
  "hex",
  "libcryptsetup-rs",
+ "pamsm",
  "ring",
  "rpassword",
  "serde",
@@ -596,6 +597,12 @@ 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"
diff --git a/Cargo.toml b/Cargo.toml
index ad486f0..c4d86c5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,6 +24,7 @@ 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"] }
 
 [build-dependencies]
 ctap_hmac = { version="0.4.2", features = ["request_multiple"] }
@@ -41,12 +42,22 @@ 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"
 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", "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" ],
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..139cd2a
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,111 @@
+#[macro_use]
+extern crate failure;
+extern crate ctap_hmac as ctap;
+#[macro_use]
+extern crate serde_derive;
+#[macro_use]
+extern crate pamsm;
+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::ffi::CStr;
+use std::str::FromStr;
+
+pub mod cli_args;
+pub mod device;
+pub mod error;
+pub mod luks;
+pub mod util;
+
+struct PamFido2Luks;
+
+impl PamFido2Luks {
+    fn open(&self, password: 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 = args
+            .get("credentials")
+            .map(|creds| {
+                <CommaSeparated<String>>::from_str(creds)
+                    .expect("Invalid credentials")
+                    .0 //TODO: proper error handling
+            })
+            .unwrap_or_default();
+        let pin = args.get("pin");
+        let device = args.get("device");
+        let name = args.get("name");
+
+        if let (Some(device), Some(name)) = (device, name) {
+            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() {
+                let secret = util::sha256(&[&perform_challenge(
+                    &credentials[..],
+                    &util::sha256(&[password.as_bytes()]),
+                    Duration::from_secs(15),
+                    pin.map(AsRef::as_ref),
+                )?
+                .0[..]]);
+                device.activate(name.as_str(), &secret[..], None)?;
+            } else {
+                unimplemented!("custom error")
+            }
+            unimplemented!()
+        } else {
+            unimplemented!("custom error")
+        }
+    }
+}
+
+impl PamServiceModule for PamFido2Luks {
+    fn authenticate(pamh: Pam, flag: PamFlag, args: Vec<String>) -> PamError {
+        let password = match pamh.get_authtok(None) {
+            Err(_) => return PamError::AUTH_ERR,
+            Ok(p) => p.map(|s| s.to_str().map(str::to_string).unwrap()),
+        };
+        if let Some(password) = password {
+            match PamFido2Luks.open(password, args) {
+                Ok(_) => PamError::SUCCESS,
+                Err(e) => match e {
+                    //TODO: output more detailed error
+                    _ => PamError::AUTH_ERR,
+                },
+            }
+        } else {
+            PamError::AUTH_ERR
+        }
+    }
+}
+
+pam_module!(PamFido2Luks);