Merge pull request #2500 from dstufft/improve-csrf

Increase the protection provided by the CSRF checks

8 files changed, 69 insertions, 35 deletions

diff --git a/docs/narr/sessions.rst b/docs/narr/sessions.rst
index d66e86258..0e895ff81 100644
--- a/docs/narr/sessions.rst
+++ b/docs/narr/sessions.rst
@@ -391,8 +391,8 @@ will return ``True``, otherwise it will raise ``HTTPBadRequest``. Optionally,
 you can specify ``raises=False`` to have the check return ``False`` instead of
 raising an exception.
 
-By default, it checks for a GET or POST parameter named ``csrf_token`` or a
-header named ``X-CSRF-Token``.
+By default, it checks for a POST parameter named ``csrf_token`` or a header
+named ``X-CSRF-Token``.
 
 .. code-block:: python
 
@@ -411,15 +411,16 @@ Checking CSRF Tokens Automatically
 
 .. versionadded:: 1.7
 
-:app:`Pyramid` supports automatically checking CSRF tokens on POST requests.
-Any other request may be checked manually. This feature can be turned on
-globally for an application using the ``pyramid.require_default_csrf`` setting.
+:app:`Pyramid` supports automatically checking CSRF tokens on requests with an
+unsafe method as defined by RFC2616. Any other request may be checked manually.
+This feature can be turned on globally for an application using the
+``pyramid.require_default_csrf`` setting.
 
 If the ``pyramid.required_default_csrf`` setting is a :term:`truthy string` or
 ``True`` then the default CSRF token parameter will be ``csrf_token``. If a
 different token is desired, it may be passed as the value. Finally, a
 :term:`falsey string` or ``False`` will turn off automatic CSRF checking
-globally on every POST request.
+globally on every request.
 
 No matter what, CSRF checking may be explicitly enabled or disabled on a
 per-view basis using the ``require_csrf`` view option. This option is of the
@@ -430,8 +431,7 @@ If ``require_csrf`` is ``True`` but does not explicitly define a token to
 check, then the token name is pulled from whatever was set in the
 ``pyramid.require_default_csrf`` setting. Finally, if that setting does not
 explicitly define a token, then ``csrf_token`` is the token required. This token
-name will be required in ``request.params`` which is a combination of the
-query string and a submitted form body.
+name will be required in ``request.POST`` which is the submitted form body.
 
 It is always possible to pass the token in the ``X-CSRF-Token`` header as well.
 There is currently no way to define an alternate name for this header without
diff --git a/docs/narr/viewconfig.rst b/docs/narr/viewconfig.rst
index e645185f5..3b8f0353a 100644
--- a/docs/narr/viewconfig.rst
+++ b/docs/narr/viewconfig.rst
@@ -195,10 +195,11 @@ Non-Predicate Arguments
 
 ``require_csrf``
 
-  CSRF checks only affect POST requests. Any other request methods will pass
-  untouched. This option is used in combination with the
-  ``pyramid.require_default_csrf`` setting to control which request parameters
-  are checked for CSRF tokens.
+  CSRF checks will affect any request method that is not defined as a "safe"
+  method by RFC2616. In pratice this means that GET, HEAD, OPTIONS, and TRACE
+  methods will pass untouched and all others methods will require CSRF. This
+  option is used in combination with the ``pyramid.require_default_csrf``
+  setting to control which request parameters are checked for CSRF tokens.
 
   This feature requires a configured :term:`session factory`.
 
@@ -459,7 +460,7 @@ configured view.
   check name.
 
   If CSRF checking is performed, the checked value will be the value of
-  ``request.params[check_name]``.  This value will be compared against the
+  ``request.POST[check_name]``.  This value will be compared against the
   value of ``request.session.get_csrf_token()``, and the check will pass if
   these two values are the same.  If the check passes, the associated view will
   be permitted to execute.  If the check fails, the associated view will not be
diff --git a/docs/whatsnew-1.7.rst b/docs/whatsnew-1.7.rst
index 83ece690e..b85e65ec1 100644
--- a/docs/whatsnew-1.7.rst
+++ b/docs/whatsnew-1.7.rst
@@ -39,14 +39,14 @@ Feature Additions
   to security checks. See https://github.com/Pylons/pyramid/pull/2021
 
 - Added a new setting, ``pyramid.require_default_csrf`` which may be used
-  to turn on CSRF checks globally for every POST request in the application.
+  to turn on CSRF checks globally for every request in the application.
   This should be considered a good default for websites built on Pyramid.
   It is possible to opt-out of CSRF checks on a per-view basis by setting
   ``require_csrf=False`` on those views.
   See :ref:`auto_csrf_checking` and
   https://github.com/Pylons/pyramid/pull/2413
 
-- Added a ``require_csrf`` view option which will enforce CSRF checks on POST
+- Added a ``require_csrf`` view option which will enforce CSRF checks on
   requests. If the CSRF check fails a ``BadCSRFToken`` exception will be
   raised and may be caught by exception views (the default response is a
   ``400 Bad Request``). This option should be used in place of the deprecated
diff --git a/pyramid/session.py b/pyramid/session.py
index fd7b5f8d5..6136e26a0 100644
--- a/pyramid/session.py
+++ b/pyramid/session.py
@@ -106,13 +106,14 @@ def check_csrf_token(request,
                      header='X-CSRF-Token',
                      raises=True):
     """ Check the CSRF token in the request's session against the value in
-    ``request.params.get(token)`` or ``request.headers.get(header)``.
-    If a ``token`` keyword is not supplied to this function, the string
-    ``csrf_token`` will be used to look up the token in ``request.params``.
-    If a ``header`` keyword is not supplied to this function, the string
-    ``X-CSRF-Token`` will be used to look up the token in ``request.headers``.
-
-    If the value supplied by param or by header doesn't match the value
+    ``request.POST.get(token)`` (if a POST request) or
+    ``request.headers.get(header)``. If a ``token`` keyword is not supplied to
+    this function, the string ``csrf_token`` will be used to look up the token
+    in ``request.POST``. If a ``header`` keyword is not supplied to this
+    function, the string ``X-CSRF-Token`` will be used to look up the token in
+    ``request.headers``.
+
+    If the value supplied by post or by header doesn't match the value
     supplied by ``request.session.get_csrf_token()``, and ``raises`` is
     ``True``, this function will raise an
     :exc:`pyramid.exceptions.BadCSRFToken` exception.
@@ -128,7 +129,18 @@ def check_csrf_token(request,
 
     .. versionadded:: 1.4a2
     """
-    supplied_token = request.params.get(token, request.headers.get(header, ""))
+    # If this is a POST/PUT/etc request, then we'll check the body to see if it
+    # has a token. We explicitly use request.POST here because CSRF tokens
+    # should never appear in an URL as doing so is a security issue. We also
+    # explicitly check for request.POST here as we do not support sending form
+    # encoded data over anything but a request.POST.
+    supplied_token = request.POST.get(token, "")
+
+    # If we were unable to locate a CSRF token in a request body, then we'll
+    # check to see if there are any headers that have a value for us.
+    if supplied_token == "":
+        supplied_token = request.headers.get(header, "")
+
     expected_token = request.session.get_csrf_token()
     if strings_differ(bytes_(expected_token), bytes_(supplied_token)):
         if raises:
diff --git a/pyramid/tests/test_config/test_views.py b/pyramid/tests/test_config/test_views.py
index 0bf0bd0b3..7be72257d 100644
--- a/pyramid/tests/test_config/test_views.py
+++ b/pyramid/tests/test_config/test_views.py
@@ -1502,8 +1502,9 @@ class TestViewsConfigurationMixin(unittest.TestCase):
             self.assertEqual(len(w), 1)
         wrapper = self._getViewCallable(config)
         request = self._makeRequest(config)
+        request.method = "POST"
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params = {'csrf_token': 'foo'}
+        request.POST = {'csrf_token': 'foo'}
         request.headers = {}
         self.assertEqual(wrapper(None, request), 'OK')
 
@@ -1595,7 +1596,7 @@ class TestViewsConfigurationMixin(unittest.TestCase):
         view = self._getViewCallable(config)
         request = self._makeRequest(config)
         request.method = 'POST'
-        request.params = {'st': 'foo'}
+        request.POST = {'st': 'foo'}
         request.headers = {}
         request.session = DummySession({'csrf_token': 'foo'})
         self.assertEqual(view(None, request), 'OK')
@@ -1609,6 +1610,7 @@ class TestViewsConfigurationMixin(unittest.TestCase):
         view = self._getViewCallable(config)
         request = self._makeRequest(config)
         request.method = 'POST'
+        request.POST = {}
         request.headers = {'X-CSRF-Token': 'foo'}
         request.session = DummySession({'csrf_token': 'foo'})
         self.assertEqual(view(None, request), 'OK')
@@ -1622,6 +1624,7 @@ class TestViewsConfigurationMixin(unittest.TestCase):
         view = self._getViewCallable(config)
         request = self._makeRequest(config)
         request.method = 'POST'
+        request.POST = {}
         request.headers = {}
         request.session = DummySession({'csrf_token': 'foo'})
         self.assertRaises(BadCSRFToken, lambda: view(None, request))
diff --git a/pyramid/tests/test_session.py b/pyramid/tests/test_session.py
index 914d28a83..4ec8f94a4 100644
--- a/pyramid/tests/test_session.py
+++ b/pyramid/tests/test_session.py
@@ -666,7 +666,8 @@ class Test_check_csrf_token(unittest.TestCase):
 
     def test_success_token(self):
         request = testing.DummyRequest()
-        request.params['csrf_token'] = request.session.get_csrf_token()
+        request.method = "POST"
+        request.POST = {'csrf_token': request.session.get_csrf_token()}
         self.assertEqual(self._callFUT(request, token='csrf_token'), True)
 
     def test_success_header(self):
@@ -676,7 +677,8 @@ class Test_check_csrf_token(unittest.TestCase):
 
     def test_success_default_token(self):
         request = testing.DummyRequest()
-        request.params['csrf_token'] = request.session.get_csrf_token()
+        request.method = "POST"
+        request.POST = {'csrf_token': request.session.get_csrf_token()}
         self.assertEqual(self._callFUT(request), True)
 
     def test_success_default_header(self):
@@ -698,8 +700,9 @@ class Test_check_csrf_token(unittest.TestCase):
     def test_token_differing_types(self):
         from pyramid.compat import text_
         request = testing.DummyRequest()
+        request.method = "POST"
         request.session['_csrft_'] = text_('foo')
-        request.params['csrf_token'] = b'foo'
+        request.POST = {'csrf_token': b'foo'}
         self.assertEqual(self._callFUT(request, token='csrf_token'), True)
 
 class DummySerializer(object):
diff --git a/pyramid/tests/test_viewderivers.py b/pyramid/tests/test_viewderivers.py
index c8fbe6f36..4613762f5 100644
--- a/pyramid/tests/test_viewderivers.py
+++ b/pyramid/tests/test_viewderivers.py
@@ -1120,6 +1120,7 @@ class TestDeriveView(unittest.TestCase):
             return response
         request = self._makeRequest()
         request.method = 'POST'
+        request.POST = {}
         request.session = DummySession({'csrf_token': 'foo'})
         request.headers = {'X-CSRF-Token': 'foo'}
         view = self.config._derive_view(inner_view, require_csrf=True)
@@ -1133,7 +1134,7 @@ class TestDeriveView(unittest.TestCase):
         request = self._makeRequest()
         request.method = 'POST'
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params['DUMMY'] = 'foo'
+        request.POST = {'DUMMY': 'foo'}
         view = self.config._derive_view(inner_view, require_csrf='DUMMY')
         result = view(None, request)
         self.assertTrue(result is response)
@@ -1154,7 +1155,7 @@ class TestDeriveView(unittest.TestCase):
         request = self._makeRequest()
         request.method = 'POST'
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params['DUMMY'] = 'bar'
+        request.POST = {'DUMMY': 'bar'}
         view = self.config._derive_view(inner_view, require_csrf='DUMMY')
         self.assertRaises(BadCSRFToken, lambda: view(None, request))
 
@@ -1163,6 +1164,18 @@ class TestDeriveView(unittest.TestCase):
         def inner_view(request): pass
         request = self._makeRequest()
         request.method = 'POST'
+        request.POST = {}
+        request.session = DummySession({'csrf_token': 'foo'})
+        request.headers = {'X-CSRF-Token': 'bar'}
+        view = self.config._derive_view(inner_view, require_csrf='DUMMY')
+        self.assertRaises(BadCSRFToken, lambda: view(None, request))
+
+    def test_csrf_view_fails_on_bad_PUT_header(self):
+        from pyramid.exceptions import BadCSRFToken
+        def inner_view(request): pass
+        request = self._makeRequest()
+        request.method = 'PUT'
+        request.POST = {}
         request.session = DummySession({'csrf_token': 'foo'})
         request.headers = {'X-CSRF-Token': 'bar'}
         view = self.config._derive_view(inner_view, require_csrf='DUMMY')
@@ -1175,7 +1188,7 @@ class TestDeriveView(unittest.TestCase):
         request = self._makeRequest()
         request.method = 'POST'
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params['csrf_token'] = 'foo'
+        request.POST = {'csrf_token': 'foo'}
         self.config.add_settings({'pyramid.require_default_csrf': 'yes'})
         view = self.config._derive_view(inner_view)
         result = view(None, request)
@@ -1188,7 +1201,7 @@ class TestDeriveView(unittest.TestCase):
         request = self._makeRequest()
         request.method = 'POST'
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params['DUMMY'] = 'foo'
+        request.POST = {'DUMMY': 'foo'}
         self.config.add_settings({'pyramid.require_default_csrf': 'DUMMY'})
         view = self.config._derive_view(inner_view)
         result = view(None, request)
@@ -1214,7 +1227,7 @@ class TestDeriveView(unittest.TestCase):
         request = self._makeRequest()
         request.method = 'POST'
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params['DUMMY'] = 'foo'
+        request.POST = {'DUMMY': 'foo'}
         self.config.add_settings({'pyramid.require_default_csrf': 'yes'})
         view = self.config._derive_view(inner_view, require_csrf='DUMMY')
         result = view(None, request)
@@ -1227,7 +1240,7 @@ class TestDeriveView(unittest.TestCase):
         request = self._makeRequest()
         request.method = 'POST'
         request.session = DummySession({'csrf_token': 'foo'})
-        request.params['DUMMY'] = 'foo'
+        request.POST = {'DUMMY': 'foo'}
         self.config.add_settings({'pyramid.require_default_csrf': 'DUMMY'})
         view = self.config._derive_view(inner_view, require_csrf=True)
         result = view(None, request)
diff --git a/pyramid/viewderivers.py b/pyramid/viewderivers.py
index 41102319d..e9ff09416 100644
--- a/pyramid/viewderivers.py
+++ b/pyramid/viewderivers.py
@@ -488,7 +488,9 @@ def csrf_view(view, info):
     wrapped_view = view
     if val:
         def csrf_view(context, request):
-            if request.method == 'POST':
+            # Assume that anything not defined as 'safe' by RFC2616 needs
+            # protection
+            if request.method not in {"GET", "HEAD", "OPTIONS", "TRACE"}:
                 check_csrf_token(request, val, raises=True)
             return view(context, request)
         wrapped_view = csrf_view