GNU bug report logs -
#21702
shell-quote-argument semantics and safety
Previous Next
Full log
View this message in rfc822 format
> From: taylanbayirli <at> gmail.com (Taylan Ulrich Bayırlı/Kammer)
> Cc: 21702 <at> debbugs.gnu.org
> Date: Sun, 18 Oct 2015 21:12:34 +0200
>
> I'd like to point out that (in the most extreme cases) people have
> actually been writing web servers and other such programs in Elisp for
> which one would normally use a general-purpose language.
>
> That is, "APIs that could be maliciously abused" is not the right way to
> look at it. It's not about the Elisp programmer abusing the API, it's
> about a malicious data source exploiting a (potential) flaw in an Elisp
> function, which Elisp programmers have relied on and thus made their
> programs vulnerable to code injection.
>
>
> That's why I was being so careful with regard to the safety guarantees
> of the "shell-quasiquote" package I contributed. I would like people to
> be able to use that as part of a general-purpose Elisp language, and so
> being safe against code injection is an absolute must. They might after
> all use it as part of a network-facing service.
>
>
> Actually that might also apply when using e.g. TRAMP, which also
> communicates with remote hosts and is a normal part of Emacs. I've been
> told it receives file names from remote hosts and passes them through
> shell-quote-argument before giving them to a shell. So maybe my
> concerns apply there as well.
>
>
> Given that, "I think 1) is now covered" is not very relieving to hear.
Item 1 was this:
> >> The function should clearly document
> >>
> >> 1) for which shells will the quoting work absolutely, i.e. lead to
> >> the given string to appear *verbatim* in an element of the ARGV of
> >> the called command,
There's nothing about safety here, only about correctness. That is
the aspect that I think is now covered, as the doc string now says for
which shells one can have correct results.
> It amounts to "I think this is safe against code injection" which is
> rather alarming to hear. Either it's very confidently known to be safe
> and so one may use it for network-facing code, or it's not confidently
> known to be safe and so one shouldn't use it for network-facing code.
> This should be documented clearly especially so that users who aren't
> very aware of injection attacks won't nonchalantly use the function for
> their network-facing code (when the function isn't known to be safe for
> this), but also so that users who are aware of such issues know they can
> use the function and don't instead invent their own thing (when it is
> known to be safe).
>
> Does that make sense?
Maybe it does, but only if we start documenting these aspects
project-wide. It makes little sense to me to do that for a single
API, and not an important one at that. But that's me.
This bug report was last modified 9 years and 211 days ago.
Previous Next
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.