- From: Eric Chen <eric.chen@sv.cmu.edu>
- Date: Wed, 29 Aug 2012 10:29:03 -0700
- To: Odin Hørthe Omdal <odinho@opera.com>
- Cc: "public-webappsec@w3.org" <public-webappsec@w3.org>
- Message-ID: <CAF8haaytMdevN61dOvKLu-tz-RBCcC2gSHkJn5EzDBwt_GAnsQ@mail.gmail.com>
I'm not sure if this idea has been discussed before, but why not have a CSP policy that disables extensions? Disabling extensions entirely is probably better than half-breaking extensions. -- -EC On Wed, Aug 29, 2012 at 4:34 AM, Odin Hørthe Omdal <odinho@opera.com> wrote: > Hello all :-) > > I've gotten some internal web site author feedback trying to implement CSP > on a web email service that I'd like to share and discuss. > > There's of course a few minor things that will get better with time. Like > browsers using prefixes and different implementations of different > versions of the spec. As well as some potential bugs found, such as using > an same-domain iframe with an email in it, and then rewriting links > therein to do target=_blank, and it was suddenly blocked. They had to open > up frame-src: * in order for the links to open. From my cursory reading of > the spec, it does seem like this is in fact intended behaviour, but I'm > not sure. > > The biggest problem however is the interference of pages' CSP policies > when an extension goes mucking around the page doing whatever it likes to > do. > > This is not the same as having a CSP-profile on the extension, as Chrome > is doing, but the other way around: > > Extensions can >> inject arbitrary javascript, css into the page and modify the DOM in any >> way. Depending on the CSP policy, those will potentially be blocked. The >> most annoying thing is that those might break your extension or the page >> in subtle ways because some things the extension does work (DOM >> manipulations), but other things fail (scripts/css injection). >> Additionally changes that do fail will generate heaps of false positive >> feedback reports, making the reporting feature a pain to sift through >> and work out "now is this a problem with my CSP poilicy, or is it some >> extension the users installed that's trying to modify the page in some >> way". >> >> I don't see any realistic solution to this. You'd have to track a whole >> bunch of manipulations and changes to the DOM as either "done by the >> page" or "done by an extension" to work out if they should be allowed or >> not. >> >> So at first I thought "what a great idea", but after two days of messing >> around and actually trying to use it, I decided that it might be >> bordering on unuseable in the real world >> > > > > I have not looked into it myself, but this is a very valid concern if we > were to implement it in Opera. What have you that have implemented this > already done about it? How does it work? Is really extensions crippled in > such a way, do they have to think about it? > > -- > Odin Hørthe Omdal (Velmont/odinho) · Core, Opera Software, > http://opera.com > >
Received on Wednesday, 29 August 2012 17:29:31 UTC