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Thanks to davidfischer for the initial patch! git-svn-id: http://code.djangoproject.com/svn/django/trunk@16360 bcc190cf-cafb-0310-a4f2-bffc1f526a37
128 lines
4.5 KiB
Text
128 lines
4.5 KiB
Text
========================
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Clickjacking Protection
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========================
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.. module:: django.middleware.clickjacking
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:synopsis: Protects against Clickjacking
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The clickjacking middleware and decorators provide easy-to-use protection
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against `clickjacking`_. This type of attack occurs when a malicious site
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tricks a user into clicking on a concealed element of another site which they
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have loaded in a hidden frame or iframe.
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.. versionadded:: 1.4
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The clickjacking middleware and decorators were added.
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.. _clickjacking: http://en.wikipedia.org/wiki/Clickjacking
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An example of clickjacking
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==========================
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Suppose an online store has a page where a logged in user can click "Buy Now" to
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purchase an item. A user has chosen to stay logged into the store all the time
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for convenience. An attacker site might create an "I Like Ponies" button on one
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of their own pages, and load the store's page in a transparent iframe such that
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the "Buy Now" button is invisibly overlaid on the "I Like Ponies" button. If the
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user visits the attacker site and clicks "I Like Ponies" he will inadvertently
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click on the online store's "Buy Now" button and unknowingly purchase the item.
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.. _clickjacking-prevention:
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Preventing clickjacking
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=======================
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Modern browsers honor the `X-Frame-Options`_ HTTP header that indicates whether
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or not a resource is allowed to load within a frame or iframe. If the response
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contains the header with a value of SAMEORIGIN then the browser will only load
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the resource in a frame if the request originated from the same site. If the
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header is set to DENY then the browser will block the resource from loading in a
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frame no matter which site made the request.
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.. _X-Frame-Options: https://developer.mozilla.org/en/The_X-FRAME-OPTIONS_response_header
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Django provides a few simple ways to include this header in responses from your
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site:
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1. A simple middleware that sets the header in all responses.
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2. A set of view decorators that can be used to override the middleware or to
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only set the header for certain views.
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How to use it
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=============
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Setting X-Frame-Options for all responses
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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To set the same X-Frame-Options value for all responses in your site, add
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``'django.middleware.clickjacking.XFrameOptionsMiddleware'`` to
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:setting:`MIDDLEWARE_CLASSES`::
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MIDDLEWARE_CLASSES = (
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...
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'django.middleware.clickjacking.XFrameOptionsMiddleware',
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...
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)
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By default, the middleware will set the X-Frame-Options header to SAMEORIGIN for
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every outgoing ``HttpResponse``. If you want DENY instead, set the
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:setting:`X_FRAME_OPTIONS` setting::
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X_FRAME_OPTIONS = 'DENY'
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When using the middleware there may be some views where you do **not** want the
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X-Frame-Options header set. For those cases, you can use a view decorator that
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tells the middleware not to set the header::
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from django.http import HttpResponse
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from django.views.decorators.clickjacking import xframe_options_exempt
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@xframe_options_exempt
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def ok_to_load_in_a_frame(request):
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return HttpResponse("This page is safe to load in a frame on any site.")
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Setting X-Frame-Options per view
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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To set the X-Frame-Options header on a per view basis, Django provides these
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decorators::
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from django.http import HttpResponse
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from django.views.decorators.clickjacking import xframe_options_deny
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from django.views.decorators.clickjacking import xframe_options_sameorigin
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@xframe_options_deny
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def view_one(request):
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return HttpResponse("I won't display in any frame!")
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@xframe_options_sameorigin
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def view_two(request):
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return HttpResponse("Display in a frame if it's from the same origin as me.")
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Note that you can use the decorators in conjunction with the middleware. Use of
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a decorator overrides the middleware.
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Limitations
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===========
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The `X-Frame-Options` header will only protect against clickjacking in a modern
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browser. Older browsers will quietly ignore the header and need `other
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clickjacking prevention techniques`_.
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Browsers that support X-Frame-Options
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* Internet Explorer 8+
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* Firefox 3.6.9+
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* Opera 10.5+
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* Safari 4+
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* Chrome 4.1+
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See also
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~~~~~~~~
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A `complete list`_ of browsers supporting X-Frame-Options.
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.. _complete list: https://developer.mozilla.org/en/The_X-FRAME-OPTIONS_response_header#Browser_compatibility
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.. _other clickjacking prevention techniques: http://en.wikipedia.org/wiki/Clickjacking#Prevention
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