83 lines
3.9 KiB
Python
83 lines
3.9 KiB
Python
"""This module is used to control authentication/authorization of Kobo sync requests.
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This module also includes research notes into the auth protocol used by Kobo devices.
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Log-in:
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When first booting a Kobo device the user must sign into a Kobo (or affiliate) account.
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Upon successful sign-in, the user is redirected to
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https://auth.kobobooks.com/CrossDomainSignIn?id=<some id>
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which serves the following response:
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<script type='text/javascript'>location.href='kobo://UserAuthenticated?userId=<redacted>&userKey<redacted>&email=<redacted>&returnUrl=https%3a%2f%2fwww.kobo.com';</script>.
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And triggers the insertion of a userKey into the device's User table.
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IMPORTANT SECURITY CAUTION:
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Together, the device's DeviceId and UserKey act as an *irrevocable* authentication
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token to most (if not all) Kobo APIs. In fact, in most cases only the UserKey is
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required to authorize the API call.
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Changing Kobo password *does not* invalidate user keys! This is apparently a known
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issue for a few years now https://www.mobileread.com/forums/showpost.php?p=3476851&postcount=13
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(although this poster hypothesised that Kobo could blacklist a DeviceId, many endpoints
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will still grant access given the userkey.)
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Official Kobo Store Api authorization:
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* For most of the endpoints we care about (sync, metadata, tags, etc), the userKey is
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passed in the x-kobo-userkey header, and is sufficient to authorize the API call.
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* Some endpoints (e.g: AnnotationService) instead make use of Bearer tokens pass through
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an authorization header. To get a BearerToken, the device makes a POST request to the
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v1/auth/device endpoint with the secret UserKey and the device's DeviceId.
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* The book download endpoint passes an auth token as a URL param instead of a header.
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Our implementation:
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For now, we rely on the official Kobo store's UserKey for authentication.
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Once authenticated, we set the login cookie on the response that will be sent back for
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the duration of the session to authorize subsequent API calls.
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Ideally we'd only perform UserKey-based authentication for the v1/initialization or the
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v1/device/auth call, however sessions don't always start with those calls.
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Because of the irrevocable power granted by the key, we only ever store and compare a
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hash of the key. To obtain their UserKey, a user can query the user table from the
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.kobo/KoboReader.sqlite database found on their device.
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This isn't exactly user friendly however.
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Some possible alternatives that require more research:
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* Instead of having users query the device database to find out their UserKey, we could
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provide a list of recent Kobo sync attempts in the calibre-web UI for users to
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authenticate sync attempts (e.g: 'this was me' button).
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* We may be able to craft a sign-in flow with a redirect back to the CalibreWeb
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server containing the KoboStore's UserKey (if the same as the devices?).
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* Can we create our own UserKey instead of relying on the real store's userkey?
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(Maybe using something like location.href=kobo://UserAuthenticated?userId=...?)
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"""
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from functools import wraps
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from flask import request, make_response
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from flask_login import login_user
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from werkzeug.security import check_password_hash
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from . import logger, ub, lm
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USER_KEY_HEADER = "x-kobo-userkey"
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USER_KEY_URL_PARAM = "kobo_userkey"
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log = logger.create()
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def disable_failed_auth_redirect_for_blueprint(bp):
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lm.blueprint_login_views[bp.name] = None
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@lm.request_loader
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def load_user_from_kobo_request(request):
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user_key = request.headers.get(USER_KEY_HEADER)
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if user_key:
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for user in (
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ub.session.query(ub.User).filter(ub.User.kobo_user_key_hash != "").all()
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):
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if check_password_hash(str(user.kobo_user_key_hash), user_key):
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# The Kobo device won't preserve the cookie accross sessions, even if we
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# were to set remember_me=true.
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login_user(user)
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return user
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log.info("Received Kobo request without a recognizable UserKey.")
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return None
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