config: harden the shared temp directory

3 files changed, 65 insertions, 8 deletions

diff --git a/src/commands/utilities.rs b/src/commands/utilities.rs
index 88829b2..f43b30e 100644
--- a/src/commands/utilities.rs
+++ b/src/commands/utilities.rs
@@ -100,7 +100,7 @@ async fn temp_op(
         .unwrap_or_default();
     let dir = format!(
         "{}/op_{}",
-        crate::config::TEMP_PATH,
+        crate::config::temp_path(),
         uuid::Uuid::new_v4()
     );
     tokio::fs::create_dir_all(&dir).await?;
@@ -506,7 +506,7 @@ async fn run_download(
     }
     let fmt = fformat.unwrap_or("mp4");
     let is_audio = matches!(fmt, "mp3" | "wav" | "m4a");
-    let dl_dir = format!("{}/dl_{}", crate::config::TEMP_PATH, uuid::Uuid::new_v4());
+    let dl_dir = format!("{}/dl_{}", crate::config::temp_path(), uuid::Uuid::new_v4());
     tokio::fs::create_dir_all(&dl_dir).await.ok();
 
     let out_template = match filename_user {
@@ -651,7 +651,7 @@ pub async fn compress(
     #[description = "Force upload to Copyparty"] serwer: Option<bool>,
 ) -> Result<()> {
     ctx.defer().await?;
-    tokio::fs::create_dir_all(crate::config::TEMP_PATH)
+    tokio::fs::create_dir_all(crate::config::temp_path())
         .await
         .ok();
 
@@ -727,7 +727,7 @@ pub async fn convert(
     #[description = "Force upload to Copyparty"] serwer: Option<bool>,
 ) -> Result<()> {
     ctx.defer().await?;
-    tokio::fs::create_dir_all(crate::config::TEMP_PATH)
+    tokio::fs::create_dir_all(crate::config::temp_path())
         .await
         .ok();
 
@@ -899,7 +899,7 @@ pub async fn download(
     #[description = "Custom output filename"] filename_user: Option<String>,
 ) -> Result<()> {
     ctx.defer().await?;
-    tokio::fs::create_dir_all(crate::config::TEMP_PATH)
+    tokio::fs::create_dir_all(crate::config::temp_path())
         .await
         .ok();
     run_download(
@@ -974,7 +974,7 @@ pub async fn message_compression(ctx: Context<'_>, message: serenity::Message) -
         return Ok(());
     }
     ctx.defer().await?;
-    tokio::fs::create_dir_all(crate::config::TEMP_PATH)
+    tokio::fs::create_dir_all(crate::config::temp_path())
         .await
         .ok();
 
@@ -1030,7 +1030,7 @@ pub async fn message_download(ctx: Context<'_>, message: serenity::Message) -> R
         return Ok(());
     }
     ctx.defer().await?;
-    tokio::fs::create_dir_all(crate::config::TEMP_PATH)
+    tokio::fs::create_dir_all(crate::config::temp_path())
         .await
         .ok();
 
diff --git a/src/config.rs b/src/config.rs
index 720c215..c05c3ae 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,6 +1,62 @@
 use std::env;
+use std::io;
+use std::sync::OnceLock;
 
-pub const TEMP_PATH: &str = "/tmp/senator_sperma";
+static TEMP_PATH: OnceLock<String> = OnceLock::new();
+
+/// Private per-process temp root. Initialized by [`init_temp_dir`] at startup.
+/// Falls back to the historical path only for code paths that run before init
+/// (tests).
+pub fn temp_path() -> &'static str {
+    TEMP_PATH
+        .get()
+        .map(String::as_str)
+        .unwrap_or("/tmp/senator_sperma")
+}
+
+/// Create/validate the temp directory with private permissions.
+///
+/// A fixed, predictable path in `/tmp` is a symlink target for any local user.
+/// Refuse a symlink (or non-directory) and force mode `0700` on the real
+/// directory before the bot writes anything into it.
+pub fn init_temp_dir() -> io::Result<()> {
+    let path = env::temp_dir().join("senator_sperma");
+    match std::fs::symlink_metadata(&path) {
+        Ok(meta) if meta.file_type().is_symlink() => {
+            return Err(io::Error::other(format!(
+                "{} is a symlink; refusing to use it",
+                path.display()
+            )));
+        }
+        Ok(meta) if !meta.is_dir() => {
+            return Err(io::Error::other(format!(
+                "{} exists and is not a directory",
+                path.display()
+            )));
+        }
+        Ok(_) => {}
+        Err(e) if e.kind() == io::ErrorKind::NotFound => {
+            let mut builder = std::fs::DirBuilder::new();
+            #[cfg(unix)]
+            {
+                use std::os::unix::fs::DirBuilderExt;
+                builder.mode(0o700);
+            }
+            builder.create(&path)?;
+        }
+        Err(e) => return Err(e),
+    }
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        std::fs::set_permissions(&path, std::fs::Permissions::from_mode(0o700))?;
+    }
+    let encoded = path.to_string_lossy().into_owned();
+    TEMP_PATH
+        .set(encoded)
+        .map_err(|_| io::Error::other("temp directory already initialized"))?;
+    Ok(())
+}
 
 #[derive(Debug, Clone)]
 pub struct Config {
diff --git a/src/main.rs b/src/main.rs
index 3483c9a..0dee2a5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -146,6 +146,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         .init();
 
     dotenvy::dotenv().ok();
+    config::init_temp_dir()?;
     config::check_env_vars();
     let config = config::Config::from_env();