2016W43 ArchCom-RFC meeting: Allow HTML in SVG? - Wikitech-l

26 Oct 2016


      Hi everyone,
For [this week's ArchCom-RFC meeting][E325], let's talk about SVG.
As you probably know, MediaWiki optionally allows for SVG uploads,
which is allowed on many Wikimedia wikis (e.g. on Commons).  However,
in order to make this preference safe to use, we need to validate the
SVG.
One thing that's allowed in the SVG spec is to embed fragments of
XHTML inside the SVG.  This isn't just a obscure spec feature; this is
understood to be the best way to embed a caption for a diagram that
allows for word wrap when the image is scaled.  Having XHTML support
also would allow for greater compatibility between MediaWiki and
real-world SVG editing tools (e.g. like draw.io)
matmarex made a suggestion in [the bug for this][T138783]:
...
We have a HTML validation library (the Sanitizer class) and it could
probably be hooked up to validating HTML in SVG file uploads. But it
would definitely require some work.
It's not officially an RFC, but I suggested it as a discussion topic
in [last week's ArchCom planning meeting][3], and no one objected.
Let's see if we can answer a couple of questions:
1.  Is this a good idea in theory?  i.e. is it possible/likely that an
experienced developer could implement something that can pass security
review, or is it conceptually flawed?
2.  Is matmarex's suggested approach a good one?
3.  Should we turn our SVG validation code into a proper library?
4.  (if there's time) Let's step through the [brion's June 30 comment][4]
This week it will be the usual time (Wednesday 21 UTC, 14 PDT, 23 CEST)
and place (#wikimedia-office).  Next week, things get complicated
because of the end of [Summer Time in Europe][5]; an announcement
about next week's meeting will hopefully find its way to the
[ArchComStatus page][6].
Rob
[E325]: https://phabricator.wikimedia.org/E325
[T138783]: https://phabricator.wikimedia.org/T138783
[3]: https://www.mediawiki.org/wiki/Architecture_committee/2016-10-19
[4]: https://phabricator.wikimedia.org/T138783#2419210
[5]: https://en.wikipedia.org/wiki/Summer_Time_in_Europe
[6]: https://www.mediawiki.org/wiki/ArchComStatus