The CSRF middleware and template tag provides easy-to-use protection against\nCross Site Request Forgeries. This type of attack occurs when a malicious\nWeb site contains a link, a form button or some JavaScript that is intended to\nperform some action on your Web site, using the credentials of a logged-in user\nwho visits the malicious site in their browser. A related type of attack,\n‘login CSRF’, where an attacking site tricks a user’s browser into logging into\na site with someone else’s credentials, is also covered.
\nThe first defense against CSRF attacks is to ensure that GET requests (and other\n‘safe’ methods, as defined by 9.1.1 Safe Methods, HTTP 1.1,\nRFC 2616 Section 9.1.1) are side-effect free. Requests via ‘unsafe’ methods,\nsuch as POST, PUT and DELETE, can then be protected by following the steps\nbelow.
\nTo take advantage of CSRF protection in your views, follow these steps:
\nThe CSRF middleware is activated by default in the\nMIDDLEWARE_CLASSES setting. If you override that setting, remember\nthat 'django.middleware.csrf.CsrfViewMiddleware' should come before any\nview middleware that assume that CSRF attacks have been dealt with.
If you disabled it, which is not recommended, you can use\ncsrf_protect() on particular views\nyou want to protect (see below).
In any template that uses a POST form, use the csrf_token tag inside\nthe <form> element if the form is for an internal URL, e.g.:
<form action="" method="post">{% csrf_token %}\nThis should not be done for POST forms that target external URLs, since\nthat would cause the CSRF token to be leaked, leading to a vulnerability.
\nIn the corresponding view functions, ensure that the\n'django.template.context_processors.csrf' context processor is\nbeing used. Usually, this can be done in one of two ways:
Use RequestContext, which always uses\n'django.template.context_processors.csrf' (no matter what template\ncontext processors are configured in the TEMPLATES setting).\nIf you are using generic views or contrib apps, you are covered already,\nsince these apps use RequestContext throughout.
Manually import and use the processor to generate the CSRF token and\nadd it to the template context. e.g.:
\nfrom django.shortcuts import render_to_response\nfrom django.template.context_processors import csrf\n\ndef my_view(request):\n c = {}\n c.update(csrf(request))\n # ... view code here\n return render_to_response("a_template.html", c)\nYou may want to write your own\nrender_to_response() wrapper that takes care\nof this step for you.
While the above method can be used for AJAX POST requests, it has some\ninconveniences: you have to remember to pass the CSRF token in as POST data with\nevery POST request. For this reason, there is an alternative method: on each\nXMLHttpRequest, set a custom X-CSRFToken header to the value of the CSRF\ntoken. This is often easier, because many JavaScript frameworks provide hooks\nthat allow headers to be set on every request.
As a first step, you must get the CSRF token itself. The recommended source for\nthe token is the csrftoken cookie, which will be set if you’ve enabled CSRF\nprotection for your views as outlined above.
Acquiring the token is straightforward:
\n// using jQuery\nfunction getCookie(name) {\n var cookieValue = null;\n if (document.cookie && document.cookie != '') {\n var cookies = document.cookie.split(';');\n for (var i = 0; i < cookies.length; i++) {\n var cookie = jQuery.trim(cookies[i]);\n // Does this cookie string begin with the name we want?\n if (cookie.substring(0, name.length + 1) == (name + '=')) {\n cookieValue = decodeURIComponent(cookie.substring(name.length + 1));\n break;\n }\n }\n }\n return cookieValue;\n}\nvar csrftoken = getCookie('csrftoken');\nThe above code could be simplified by using the JavaScript Cookie library to replace getCookie:
var csrftoken = Cookies.get('csrftoken');\nFinally, you’ll have to actually set the header on your AJAX request, while\nprotecting the CSRF token from being sent to other domains using\nsettings.crossDomain in jQuery 1.5.1 and\nnewer:
\nfunction csrfSafeMethod(method) {\n // these HTTP methods do not require CSRF protection\n return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));\n}\n$.ajaxSetup({\n beforeSend: function(xhr, settings) {\n if (!csrfSafeMethod(settings.type) && !this.crossDomain) {\n xhr.setRequestHeader("X-CSRFToken", csrftoken);\n }\n }\n});\nWhen using a different template engine than Django’s built-in engine, you can\nset the token in your forms manually after making sure it’s available in the\ntemplate context.
\nFor example, in the Jinja2 template language, your form could contain the\nfollowing:
\n<div style="display:none">\n <input type="hidden" name="csrfmiddlewaretoken" value="{{ csrf_token }}">\n</div>\nYou can use JavaScript similar to the AJAX code above to get\nthe value of the CSRF token.
\nRather than adding CsrfViewMiddleware as a blanket protection, you can use\nthe csrf_protect decorator, which has exactly the same functionality, on\nparticular views that need the protection. It must be used both on views\nthat insert the CSRF token in the output, and on those that accept the POST form\ndata. (These are often the same view function, but not always).
Use of the decorator by itself is not recommended, since if you forget to\nuse it, you will have a security hole. The ‘belt and braces’ strategy of using\nboth is fine, and will incur minimal overhead.
\nDecorator that provides the protection of CsrfViewMiddleware to a view.
Usage:
\nfrom django.views.decorators.csrf import csrf_protect\nfrom django.shortcuts import render\n\n@csrf_protect\ndef my_view(request):\n c = {}\n # ...\n return render(request, "a_template.html", c)\nIf you are using class-based views, you can refer to\nDecorating class-based views.
\nBy default, a ‘403 Forbidden’ response is sent to the user if an incoming\nrequest fails the checks performed by CsrfViewMiddleware. This should\nusually only be seen when there is a genuine Cross Site Request Forgery, or\nwhen, due to a programming error, the CSRF token has not been included with a\nPOST form.
The error page, however, is not very friendly, so you may want to provide your\nown view for handling this condition. To do this, simply set the\nCSRF_FAILURE_VIEW setting.
The CSRF protection is based on the following things:
\nA CSRF cookie that is set to a random value (a session independent nonce, as\nit is called), which other sites will not have access to.
\nThis cookie is set by CsrfViewMiddleware. It is meant to be permanent,\nbut since there is no way to set a cookie that never expires, it is sent with\nevery response that has called django.middleware.csrf.get_token()\n(the function used internally to retrieve the CSRF token).
A hidden form field with the name ‘csrfmiddlewaretoken’ present in all\noutgoing POST forms. The value of this field is the value of the CSRF\ncookie.
\nThis part is done by the template tag.
\nFor all incoming requests that are not using HTTP GET, HEAD, OPTIONS or\nTRACE, a CSRF cookie must be present, and the ‘csrfmiddlewaretoken’ field\nmust be present and correct. If it isn’t, the user will get a 403 error.
\nThis check is done by CsrfViewMiddleware.
In addition, for HTTPS requests, strict referer checking is done by\nCsrfViewMiddleware. This is necessary to address a Man-In-The-Middle\nattack that is possible under HTTPS when using a session independent nonce,\ndue to the fact that HTTP ‘Set-Cookie’ headers are (unfortunately) accepted\nby clients that are talking to a site under HTTPS. (Referer checking is not\ndone for HTTP requests because the presence of the Referer header is not\nreliable enough under HTTP.)
This ensures that only forms that have originated from your Web site can be used\nto POST data back.
\nIt deliberately ignores GET requests (and other requests that are defined as\n‘safe’ by RFC 2616). These requests ought never to have any potentially\ndangerous side effects , and so a CSRF attack with a GET request ought to be\nharmless. RFC 2616 defines POST, PUT and DELETE as ‘unsafe’, and all other\nmethods are assumed to be unsafe, for maximum protection.
\nIf the csrf_token template tag is used by a template (or the\nget_token function is called some other way), CsrfViewMiddleware will\nadd a cookie and a Vary: Cookie header to the response. This means that the\nmiddleware will play well with the cache middleware if it is used as instructed\n(UpdateCacheMiddleware goes before all other middleware).
However, if you use cache decorators on individual views, the CSRF middleware\nwill not yet have been able to set the Vary header or the CSRF cookie, and the\nresponse will be cached without either one. In this case, on any views that\nwill require a CSRF token to be inserted you should use the\ndjango.views.decorators.csrf.csrf_protect() decorator first:
from django.views.decorators.cache import cache_page\nfrom django.views.decorators.csrf import csrf_protect\n\n@cache_page(60 * 15)\n@csrf_protect\ndef my_view(request):\n ...\nIf you are using class-based views, you can refer to Decorating\nclass-based views.
\nThe CsrfViewMiddleware will usually be a big hindrance to testing view\nfunctions, due to the need for the CSRF token which must be sent with every POST\nrequest. For this reason, Django’s HTTP client for tests has been modified to\nset a flag on requests which relaxes the middleware and the csrf_protect\ndecorator so that they no longer rejects requests. In every other respect\n(e.g. sending cookies etc.), they behave the same.
If, for some reason, you want the test client to perform CSRF\nchecks, you can create an instance of the test client that enforces\nCSRF checks:
\n>>> from django.test import Client\n>>> csrf_client = Client(enforce_csrf_checks=True)\nSubdomains within a site will be able to set cookies on the client for the whole\ndomain. By setting the cookie and using a corresponding token, subdomains will\nbe able to circumvent the CSRF protection. The only way to avoid this is to\nensure that subdomains are controlled by trusted users (or, are at least unable\nto set cookies). Note that even without CSRF, there are other vulnerabilities,\nsuch as session fixation, that make giving subdomains to untrusted parties a bad\nidea, and these vulnerabilities cannot easily be fixed with current browsers.
\nCertain views can have unusual requirements that mean they don’t fit the normal\npattern envisaged here. A number of utilities can be useful in these\nsituations. The scenarios they might be needed in are described in the following\nsection.
\nThe examples below assume you are using function-based views. If you\nare working with class-based views, you can refer to Decorating\nclass-based views.
\nThis decorator marks a view as being exempt from the protection ensured by\nthe middleware. Example:
\nfrom django.views.decorators.csrf import csrf_exempt\nfrom django.http import HttpResponse\n\n@csrf_exempt\ndef my_view(request):\n return HttpResponse('Hello world')\nNormally the csrf_token template tag will not work if\nCsrfViewMiddleware.process_view or an equivalent like csrf_protect\nhas not run. The view decorator requires_csrf_token can be used to\nensure the template tag does work. This decorator works similarly to\ncsrf_protect, but never rejects an incoming request.
Example:
\nfrom django.views.decorators.csrf import requires_csrf_token\nfrom django.shortcuts import render\n\n@requires_csrf_token\ndef my_view(request):\n c = {}\n # ...\n return render(request, "a_template.html", c)\nThis decorator forces a view to send the CSRF cookie.
\nMost views requires CSRF protection, but a few do not.
\nSolution: rather than disabling the middleware and applying csrf_protect to\nall the views that need it, enable the middleware and use\ncsrf_exempt().
There are cases when CsrfViewMiddleware.process_view may not have run\nbefore your view is run - 404 and 500 handlers, for example - but you still\nneed the CSRF token in a form.
Solution: use requires_csrf_token()
There may be some views that are unprotected and have been exempted by\ncsrf_exempt, but still need to include the CSRF token.
Solution: use csrf_exempt() followed by\nrequires_csrf_token(). (i.e. requires_csrf_token\nshould be the innermost decorator).
A view needs CSRF protection under one set of conditions only, and mustn’t have\nit for the rest of the time.
\nSolution: use csrf_exempt() for the whole\nview function, and csrf_protect() for the\npath within it that needs protection. Example:
from django.views.decorators.csrf import csrf_exempt, csrf_protect\n\n@csrf_exempt\ndef my_view(request):\n\n @csrf_protect\n def protected_path(request):\n do_something()\n\n if some_condition():\n return protected_path(request)\n else:\n do_something_else()\nA page makes a POST request via AJAX, and the page does not have an HTML form\nwith a csrf_token that would cause the required CSRF cookie to be sent.
Solution: use ensure_csrf_cookie() on the\nview that sends the page.
Because it is possible for the developer to turn off the CsrfViewMiddleware,\nall relevant views in contrib apps use the csrf_protect decorator to ensure\nthe security of these applications against CSRF. It is recommended that the\ndevelopers of other reusable apps that want the same guarantees also use the\ncsrf_protect decorator on their views.
A number of settings can be used to control Django’s CSRF behavior:
\n\n