root: subclass SessionMiddleware to set Secure and SameSite flag depending on context

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>
This commit is contained in:
Jens Langhammer 2021-07-06 14:48:36 +02:00
parent 5e03b27348
commit 007838fcf2
2 changed files with 93 additions and 2 deletions

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@ -0,0 +1,89 @@
"""Dynamically set SameSite depending if the upstream connection is TLS or not"""
import time
from django.conf import settings
from django.contrib.sessions.backends.base import UpdateError
from django.contrib.sessions.exceptions import SessionInterrupted
from django.contrib.sessions.middleware import (
SessionMiddleware as UpstreamSessionMiddleware,
)
from django.http.request import HttpRequest
from django.http.response import HttpResponse
from django.utils.cache import patch_vary_headers
from django.utils.http import http_date
class SessionMiddleware(UpstreamSessionMiddleware):
"""Dynamically set SameSite depending if the upstream connection is TLS or not"""
@staticmethod
def is_secure(request: HttpRequest) -> bool:
"""Check if request is TLS'd or localhost"""
if request.is_secure():
return True
host, _, _ = request.get_host().partition(":")
if host == "localhost" and settings.DEBUG:
return True
return False
def process_response(
self, request: HttpRequest, response: HttpResponse
) -> HttpResponse:
"""
If request.session was modified, or if the configuration is to save the
session every time, save the changes and set a session cookie or delete
the session cookie if the session has been emptied.
"""
try:
accessed = request.session.accessed
modified = request.session.modified
empty = request.session.is_empty()
except AttributeError:
return response
# Set SameSite based on whether or not the request is secure
secure = SessionMiddleware.is_secure(request)
same_site = "None" if secure else "Lax"
# First check if we need to delete this cookie.
# The session should be deleted only if the session is entirely empty.
if settings.SESSION_COOKIE_NAME in request.COOKIES and empty:
response.delete_cookie(
settings.SESSION_COOKIE_NAME,
path=settings.SESSION_COOKIE_PATH,
domain=settings.SESSION_COOKIE_DOMAIN,
samesite=same_site,
)
patch_vary_headers(response, ("Cookie",))
else:
if accessed:
patch_vary_headers(response, ("Cookie",))
if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:
if request.session.get_expire_at_browser_close():
max_age = None
expires = None
else:
max_age = request.session.get_expiry_age()
expires_time = time.time() + max_age
expires = http_date(expires_time)
# Save the session data and refresh the client cookie.
# Skip session save for 500 responses, refs #3881.
if response.status_code != 500:
try:
request.session.save()
except UpdateError:
raise SessionInterrupted(
"The request's session was deleted before the "
"request completed. The user may have logged "
"out in a concurrent request, for example."
)
response.set_cookie(
settings.SESSION_COOKIE_NAME,
request.session.session_key,
max_age=max_age,
expires=expires,
domain=settings.SESSION_COOKIE_DOMAIN,
path=settings.SESSION_COOKIE_PATH,
secure=secure,
httponly=settings.SESSION_COOKIE_HTTPONLY or None,
samesite=same_site,
)
return response

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@ -203,14 +203,16 @@ DJANGO_REDIS_IGNORE_EXCEPTIONS = True
DJANGO_REDIS_LOG_IGNORED_EXCEPTIONS = True
SESSION_ENGINE = "django.contrib.sessions.backends.cache"
SESSION_CACHE_ALIAS = "default"
SESSION_COOKIE_SAMESITE = "None"
# Configured via custom SessionMiddleware
# SESSION_COOKIE_SAMESITE = "None"
# SESSION_COOKIE_SECURE = True
SESSION_EXPIRE_AT_BROWSER_CLOSE = True
MESSAGE_STORAGE = "authentik.root.messages.storage.ChannelsStorage"
MIDDLEWARE = [
"django_prometheus.middleware.PrometheusBeforeMiddleware",
"django.contrib.sessions.middleware.SessionMiddleware",
"authentik.root.middleware.SessionMiddleware",
"django.contrib.auth.middleware.AuthenticationMiddleware",
"authentik.core.middleware.RequestIDMiddleware",
"authentik.tenants.middleware.TenantMiddleware",