W3C home > Mailing lists > Public > public-webappsec@w3.org > December 2013

Re: Hashes/Nonce Source and unsafe-inline

From: Dionysis Zindros <dionyziz@gmail.com>
Date: Fri, 13 Dec 2013 00:13:14 -0800
Message-ID: <CAE-c3mcggRogEVz4ptLkOOA6wmUDd-n1AxpBxcwKC78vtoKwNw@mail.gmail.com>
To: Devdatta Akhawe <dev.akhawe@gmail.com>
Cc: Mike West <mkwst@google.com>, "public-webappsec@w3.org" <public-webappsec@w3.org>, Dan Veditz <dveditz@mozilla.com>
I'm not really sure what you mean by this, could you elaborate, maybe
with an example?

Thank you.

On Thu, Dec 12, 2013 at 6:01 PM, Devdatta Akhawe <dev.akhawe@gmail.com> wrote:
> I agree with you on hash sources. I don't believe this is true for
> nonce sources, since one of the use cases nonces support is including
> scripts from URLs that you only know at runtime.
> --dev
> On 12 December 2013 16:00, Dionysis Zindros <dionyziz@gmail.com> wrote:
>> On Thu, Dec 12, 2013 at 3:34 PM, Devdatta Akhawe <dev.akhawe@gmail.com> wrote:
>>> Hi
>>> [creating a separate thread since there were other discussions ongoing
>>> in the other]
>>>> 2. 'unsafe-inline' is disabled if either a hash or nonce is present.
>>>>      [3] https://dvcs.w3.org/hg/content-security-policy/rev/8db37e53da82
>>> Imagine a website that wants to control what external scripts are
>>> loaded. The website uses inline  event handlers too. The hosts for
>>> external scripts can be dynamic (e.g., it is on a CDN) and thus it
>>> uses nonces to load them at runtime. In the new design, all the event
>>> handlers would stop working. I am not sure this is what we want.
>> Inline event handlers are insecure and prone to XSS, so we want to
>> block them. There's no point in enabling both unsafe-inline and (hash
>> or nonce) at the same time. The point of a hash or a nonce is to block
>> all inline scripts except the ones whitelisted. Allowing inline
>> scripts completely defeats the purpose of having hashes or nonces.
>>> Thanks
>>> Dev
Received on Friday, 13 December 2013 08:14:01 UTC

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