feat: support custom /c mountpoints (nullpo-head#13)

Detect mount from /etc/wsl.conf, store specified MNT in
the module's config file, read it in the Rust module

Author: jonaskuske

install.sh

@@ -41,8 +41,19 @@ if [ ! -e build/pam_wsl_hello.so ] || \
 fi
 
 MNT=/mnt/c
+
+if [ -f "/etc/wsl.conf" ]; then
+  # Get value specified in the form of 'root = /some/path/'
+  WSL_CONF_ROOT="$(cat /etc/wsl.conf | sed -n "s/^[[:space:]]*root[[:space:]]*=\(.*\)/\1/p")"
+  # Trim path
+  WSL_CONF_ROOT="$(echo $WSL_CONF_ROOT | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')"
+  if [ -n "$WSL_CONF_ROOT" ]; then
+    MNT="${WSL_CONF_ROOT}c"
+  fi
+fi
+
 if [[ ! -e "${MNT}" ]]; then
-  echo "'/mnt/c' was not found. Please input the mount point of your C drive to invoke Windows commands."
+  echo "'$MNT' was not found. Please input the mount point of your C drive to invoke Windows commands."
   echo -n ": "
   read MNT
 fi
@@ -106,6 +117,7 @@ if [ ! -e "/etc/pam_wsl_hello/config" ] || prompt_yn "'/etc/pam_wsl_hello/config
   set -x
   sudo touch /etc/pam_wsl_hello/config
   sudo echo "authenticator_path = \"$PAM_WSL_HELLO_WINPATH/WindowsHelloAuthenticator/WindowsHelloAuthenticator.exe\"" | sudo tee /etc/pam_wsl_hello/config
+  sudo echo "win_mnt = \"$MNT\"" | sudo tee -a /etc/pam_wsl_hello/config
 else
   echo "Skipping creation of '/etc/pam_wsl_hello/config'..."
 fi

src/auth.rs

@@ -11,6 +11,7 @@ use std::io::prelude::*;
 use std::process::{Command, Stdio};
 use std::os::unix::io::{AsRawFd, FromRawFd};
 use std::fmt;
+use std::path::Path;
 use openssl;
 use bindings::*;
 use openssl::sign::Verifier;
@@ -90,9 +91,9 @@ impl fmt::Display for ConfigError {
         match *self {
             ConfigError::Io(ref ioerr) => write!(f, "{}", ioerr),
             ConfigError::Toml(_) => write!(f, "TOML format error"),
-            ConfigError::MissingField(_) => write!(f, "field: 'authenticator_path' is not found"),
-            ConfigError::InvalidValueType(_) => {
-                write!(f, "field: 'authenticator_path' has an invalid value type")
+            ConfigError::MissingField(ref field) => write!(f, "field: '{}' is not found", field),
+            ConfigError::InvalidValueType(ref field) => {
+                write!(f, "field: '{}' has an invalid value type", field)
             }
         }
     }
@@ -114,6 +115,20 @@ fn get_authenticator_path() -> Result<String, ConfigError> {
     Ok(authenticator_path.to_owned())
 }
 
+fn get_win_mnt() -> Result<String, ConfigError> {
+    let mut config_file = File::open("/etc/pam_wsl_hello/config")?;
+    let mut config = String::new();
+    config_file.read_to_string(&mut config)?;
+
+    let config_value = config.parse::<Value>()?;
+    let win_mnt = config_value
+        .get("win_mnt")
+        .ok_or(ConfigError::MissingField("win_mnt".to_owned()))?
+        .as_str()
+        .ok_or(ConfigError::InvalidValueType("win_mnt".to_owned()))?;
+    Ok(win_mnt.to_owned())
+}
+
 #[derive(Debug)]
 enum HelloAuthenticationError {
     GetUserError(i32),
@@ -206,7 +221,7 @@ fn authenticate_via_hello(pamh: *mut pam_handle_t) -> Result<i32, HelloAuthentic
         let authenticator_path = get_authenticator_path()?;
         let authenticator = Command::new(&authenticator_path)
             .arg(credential_key_name)
-            .current_dir("/mnt/c")
+            .current_dir(Path::new(&get_win_mnt()?))
             .stdin(challenge_tmpfile_in)
             .stdout(Stdio::piped())
             .spawn()