Investigate passwordmanager permissions

[ryardley]

          _:warning: Potential issue_

Potential race condition in file permission enforcement

The methods get_key and delete_key in FilePasswordManager call ensure_file_permissions to verify and set file permissions before accessing or deleting the keyfile. However, there is a potential race condition between checking the permissions and performing the file operation.

Consider using fs::OpenOptions with appropriate flags to open the file securely, minimizing the window for race conditions.

Example adjustment in get_key:

 async fn get_key(&self) -> Result<Zeroizing<Vec<u8>>> {
-    let path = &self.path;
-
-    ensure_file_permissions(path, 0o400)?;
-
-    let bytes = fs::read(&self.path).context("Failed to access keyfile")?;
+    let mut file = OpenOptions::new()
+        .read(true)
+        .custom_flags(libc::O_NOFOLLOW)
+        .mode(0o400)
+        .open(&self.path)
+        .context("Failed to securely open keyfile")?;
+
+    let mut bytes = Vec::new();
+    file.read_to_end(&mut bytes).context("Failed to read keyfile")?;

     Ok(Zeroizing::new(bytes))
 }

Note: The use of custom_flags(libc::O_NOFOLLOW) prevents symbolic link attacks. Ensure libc is imported and available.

Also applies to: 105-106

_Originally posted by @coderabbitai[bot] in https://github.com/gnosisguild/enclave/pull/156#discussion_r1818435683_

[ryardley]

On investigation this is not worth pursuing as secrets are generally mounted as tmpfs