[PATCH] Re: [BUG][Security] begin_src :var evaluated before the prompt to confirm execution

[Ihor Radchenko]

Max Nikulin <manikulin@gmail.com> writes:

> Consider the following source block
>
> ---- >8 ----
> #+begin_src elisp :var a=(message "%s" "pwnd")
>    a
> #+end_src
> ---- 8< ----
>
> Open the "*Messages*" buffer (C-h e) and try to evaluate the source 
> block (C-c C-c).
>
> Actual result:
> "pwnd" message appears in "*Messages*" simultaneously with user prompt 
> whether the code should be executed.
>
> Expected result:
> No code from the Org buffer and linked files is executed prior to 
> confirmation from the user.

Confirmed.

See the attached tentative patch.
I tried to balance between annoying users with query and not evaluating
unsafe code: '-quoted lists and symbols are still evaluated without
prompt.

Let me know if you see any potential issues.

>From 961a3ee38a2b9521427fddea5102d003f39b88d6 Mon Sep 17 00:00:00 2001
Message-Id: 
<961a3ee38a2b9521427fddea5102d003f39b88d6.1666926796.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Fri, 28 Oct 2022 11:09:50 +0800
Subject: [PATCH] org-babel-read: Obey `org-confirm-babel-evaluate'

* lisp/ob-core.el (org-babel-read): Do not execute arbitrary Elisp
without prompt, according to `org-confirm-babel-evaluate'.

Reported-by: Max Nikulin <manikulin@gmail.com>
Link: https://orgmode.org/list/tjct9e$179u$1@ciao.gmane.io
---
 lisp/ob-core.el | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/lisp/ob-core.el b/lisp/ob-core.el
index 518831ec6..e10ab401c 100644
--- a/lisp/ob-core.el
+++ b/lisp/ob-core.el
@@ -3165,7 +3165,16 @@ (defun org-babel-read (cell &optional inhibit-lisp-eval)
        ((and (not inhibit-lisp-eval)
              (or (memq (string-to-char cell) '(?\( ?' ?` ?\[))
                  (string= cell "*this*")))
-        (eval (read cell) t))
+         ;; Prevent arbitrary function calls.
+         (if (and (memq (string-to-char cell) '(?\( ?`))
+                  (not (org-babel-confirm-evaluate
+                      ;; See `org-babel-get-src-block-info'.
+                      (list "emacs-lisp" (format "%S" cell)
+                            '((:eval . yes)) nil (format "%S" cell)
+                            nil nil))))
+             ;; Not allowed.
+             (user-error "Evaluation of elisp code %S aborted." cell)
+          (eval (read cell) t)))
        ((save-match-data
            (and (string-match "^[[:space:]]*\"\\(.*\\)\"[[:space:]]*$" cell)
                 (not (string-match "[^\\]\"" (match-string 1 cell)))))
-- 
2.35.1


-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>