Fixed #21002 -- Documented JSON session serialization requires string keys

Thanks jeroen.pulles at redslider.net for the report.
This commit is contained in:
Tim Graham 2013-09-03 07:48:03 -04:00
parent b6889c68d7
commit 3baf1d1042
2 changed files with 22 additions and 5 deletions

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@ -745,7 +745,8 @@ Default session serialization switched to JSON
Historically, :mod:`django.contrib.sessions` used :mod:`pickle` to serialize Historically, :mod:`django.contrib.sessions` used :mod:`pickle` to serialize
session data before storing it in the backend. If you're using the :ref:`signed session data before storing it in the backend. If you're using the :ref:`signed
cookie session backend<cookie-session-backend>` and :setting:`SECRET_KEY` is cookie session backend<cookie-session-backend>` and :setting:`SECRET_KEY` is
known by an attacker, the attacker could insert a string into his session known by an attacker (there isn't an inherent vulnerability in Django that
would cause it to leak), the attacker could insert a string into his session
which, when unpickled, executes arbitrary code on the server. The technique for which, when unpickled, executes arbitrary code on the server. The technique for
doing so is simple and easily available on the internet. Although the cookie doing so is simple and easily available on the internet. Although the cookie
session storage signs the cookie-stored data to prevent tampering, a session storage signs the cookie-stored data to prevent tampering, a
@ -759,7 +760,9 @@ For backwards compatibility, this setting defaulted to using :mod:`pickle`
in Django 1.5.3, but we've changed the default to JSON in 1.6. If you upgrade in Django 1.5.3, but we've changed the default to JSON in 1.6. If you upgrade
and switch from pickle to JSON, sessions created before the upgrade will be and switch from pickle to JSON, sessions created before the upgrade will be
lost. While JSON serialization does not support all Python objects like lost. While JSON serialization does not support all Python objects like
:mod:`pickle` does, we highly recommend using JSON-serialized sessions. See the :mod:`pickle` does, we highly recommend using JSON-serialized sessions. Also,
as JSON requires string keys, you will likely run into problems if you are
using non-string keys in ``request.session``. See the
:ref:`session_serialization` documentation for more details. :ref:`session_serialization` documentation for more details.
Miscellaneous Miscellaneous

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@ -314,7 +314,8 @@ Session serialization
Before version 1.6, Django defaulted to using :mod:`pickle` to serialize Before version 1.6, Django defaulted to using :mod:`pickle` to serialize
session data before storing it in the backend. If you're using the :ref:`signed session data before storing it in the backend. If you're using the :ref:`signed
cookie session backend<cookie-session-backend>` and :setting:`SECRET_KEY` is cookie session backend<cookie-session-backend>` and :setting:`SECRET_KEY` is
known by an attacker, the attacker could insert a string into his session known by an attacker (there isn't an inherent vulnerability in Django that
would cause it to leak), the attacker could insert a string into his session
which, when unpickled, executes arbitrary code on the server. The technique for which, when unpickled, executes arbitrary code on the server. The technique for
doing so is simple and easily available on the internet. Although the cookie doing so is simple and easily available on the internet. Although the cookie
session storage signs the cookie-stored data to prevent tampering, a session storage signs the cookie-stored data to prevent tampering, a
@ -338,8 +339,21 @@ Bundled Serializers
.. class:: serializers.JSONSerializer .. class:: serializers.JSONSerializer
A wrapper around the JSON serializer from :mod:`django.core.signing`. Can A wrapper around the JSON serializer from :mod:`django.core.signing`. Can
only serialize basic data types. See the :ref:`custom-serializers` section only serialize basic data types.
for more details.
In addition, as JSON supports only string keys, note that using non-string
keys in ``request.session`` won't work as expected::
>>> # initial assignment
>>> request.session[0] = 'bar'
>>> # subsequent requests following serialization & deserialization
>>> # of session data
>>> request.session[0] # KeyError
>>> request.session['0']
'bar'
See the :ref:`custom-serializers` section for more details on limitations
of JSON serialization.
.. class:: serializers.PickleSerializer .. class:: serializers.PickleSerializer