[Chicken-hackers] [PATCH 2/4] csi: fix untrusted code execution by (load)ing ./.csirc

[Florian Zumbiehl]

Remove (load)ing of ./.csirc on csi startup as it can lead to execution of
untrusted code.
---

I think a replacement mechanism is not necessary, anyone who wants the old
behaviour can just add appropriate code to their ~/.csirc.

The TOCTOU sporadic failure bug I have left in as I don't have a clue how
to fix that.

 csi.scm |   13 ++++++-------
 1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/csi.scm b/csi.scm
index 6881d7b..ab650ee 100644
--- a/csi.scm
+++ b/csi.scm
@@ -1016,13 +1016,12 @@ EOF
                          (cons (cadr p) (loop (cddr p)))) ) ]
                [else '()] ) ) )
       (define (loadinit)
-       (let ([fn (##sys#string-append "./" init-file)])
-         (if (file-exists? fn)
-             (load fn)
-             (let* ([prefix (chop-separator (or (get-environment-variable 
"HOME") "."))]
-                    [fn (string-append prefix "/" init-file)] )
-               (when (file-exists? fn) 
-                 (load fn) ) ) ) ) )
+        (and-let* ((home (get-environment-variable "HOME")))
+                  (when (= (string-length home) 0)
+                    (##sys#error "invalid (empty) $HOME"))
+                  (let ((fn (string-append (chop-separator home) "/" 
init-file)))
+                    (when (file-exists? fn)
+                      (load fn) ) ) ) )
       (define (evalstring str #!optional (rec (lambda _ (void))))
        (let ((in (open-input-string str)))
          (do ([x (read in) (read in)])
-- 
1.7.2.5