"Knut Petersen" <[email protected]> writes:
>> We also have to inspect every other use of scm_system,
> e.g. backend_library.scm .If someone offers to run lilypond on a
> server, a similar attack might be (probably is) possible.
>
> Converting to pdf looks pretty save to me.
>
> We do filter characters in \bookOutputSuffix, but something like
>
> ~~~
> \version "2.21.0"
> \book {
> #(set! (paper-variable #f 'output-filename)
> "/home/knut/\"&xterm -e find ~&" ) {c}
> }
> ~~~
>
> is allowed. But converting to pdf does use ly:system, and that in the
> end translates to a call of glibs g_spawn_sync that uses execve. So we
> really produce the file /home/knut/"&xterm -e find ~&.pdf here and do
> not execute anything but ghostscript.
Assuming that exec works fine enough on Windows for this (I think
Windows has to direct everything through a single-string command line).
But if it doesn't, we can call it "somebody else's problem" I presume.
Likely that of our cross compilation C standard library.
--
David Kastrup
---
** [issues:#5243] Fix security problem in lilypond-invoke-editor**
**Status:** Started
**Created:** Thu Nov 23, 2017 08:35 AM UTC by Knut Petersen
**Last Updated:** Fri Nov 24, 2017 09:57 PM UTC
**Owner:** Knut Petersen
Fix security problem in lilypond-invoke-editor
If lilypond-invoke-editor was installed as a general
uri-helper it was easy to abuse it to execute arbitrary
code on an attacked system for non-textedit URIs.
This part of the problem was discovered and reported
to our bug-lilypond mailing list by Gabriel Corona.
But also pure textedit URIs were vulnerable, an
example is the URI
textedit:///:&xterm -e find ~/&:x:
that executes "find ~/" in a xterm.
With this patch lilypond-invoke-editor only
handles textedit URIs, and it does no longer
use the systems command processor but
guiles system* procedure for those URIs.
Also the script will abort if the line, char and
column fields of a textedit URI contain anything
but digits.
We could have fixed URI passing to the browser,
but it is not our job to provide a general URI helper.
Other software (e.g. xdg-open and friends) should
be used for that.
The security problem fixed now was introduced
into lilypond in the year 2005.
Signed-off-by: Knut Petersen <[email protected]>
http://codereview.appspot.com/336240043
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