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69 lines
2.8 KiB
69 lines
2.8 KiB
2 months ago
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From f4cc61636947b5c2f0afc67174dd369fe3277aa8 Mon Sep 17 00:00:00 2001
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From: Ihor Radchenko <yantar92@posteo.net>
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Date: Tue, 18 Jun 2024 13:06:44 +0200
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Subject: org-link-expand-abbrev: Do not evaluate arbitrary unsafe Elisp code
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* lisp/org/ol.el (org-link-expand-abbrev): Refuse expanding %(...) link
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abbrevs that specify unsafe function. Instead, display a warning, and
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do not expand the abbrev. Clear all the text properties from the
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returned link, to avoid any potential vulnerabilities caused by
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properties that may contain arbitrary Elisp.
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---
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lisp/org/ol.el | 40 +++++++++++++++++++++++++++++-----------
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1 file changed, 29 insertions(+), 11 deletions(-)
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diff --git a/lisp/org/ol.el b/lisp/org/ol.el
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index 7a7f4f5..8a556c7 100644
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--- a/lisp/org/ol.el
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+++ b/lisp/org/ol.el
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@@ -1152,17 +1152,35 @@ Abbreviations are defined in `org-link-abbrev-alist'."
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(if (not as)
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link
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(setq rpl (cdr as))
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- (cond
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- ((symbolp rpl) (funcall rpl tag))
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- ((string-match "%(\\([^)]+\\))" rpl)
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- (replace-match
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- (save-match-data
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- (funcall (intern-soft (match-string 1 rpl)) tag))
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- t t rpl))
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- ((string-match "%s" rpl) (replace-match (or tag "") t t rpl))
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- ((string-match "%h" rpl)
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- (replace-match (url-hexify-string (or tag "")) t t rpl))
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- (t (concat rpl tag)))))))
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+ ;; Drop any potentially dangerous text properties like
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+ ;; `modification-hooks' that may be used as an attack vector.
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+ (substring-no-properties
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+ (cond
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+ ((symbolp rpl) (funcall rpl tag))
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+ ((string-match "%(\\([^)]+\\))" rpl)
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+ (let ((rpl-fun-symbol (intern-soft (match-string 1 rpl))))
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+ ;; Using `unsafep-function' is not quite enough because
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+ ;; Emacs considers functions like `genenv' safe, while
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+ ;; they can potentially be used to expose private system
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+ ;; data to attacker if abbreviated link is clicked.
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+ (if (or (eq t (get rpl-fun-symbol 'org-link-abbrev-safe))
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+ (eq t (get rpl-fun-symbol 'pure)))
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+ (replace-match
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+ (save-match-data
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+ (funcall (intern-soft (match-string 1 rpl)) tag))
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+ t t rpl)
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+ (org-display-warning
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+ (format "Disabling unsafe link abbrev: %s
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+You may mark function safe via (put '%s 'org-link-abbrev-safe t)"
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+ rpl (match-string 1 rpl)))
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+ (setq org-link-abbrev-alist-local (delete as org-link-abbrev-alist-local)
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+ org-link-abbrev-alist (delete as org-link-abbrev-alist))
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+ link
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+ )))
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+ ((string-match "%s" rpl) (replace-match (or tag "") t t rpl))
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+ ((string-match "%h" rpl)
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+ (replace-match (url-hexify-string (or tag "")) t t rpl))
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+ (t (concat rpl tag))))))))
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(defun org-link-open (link &optional arg)
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"Open a link object LINK.
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--
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cgit v1.1
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