libervia-backend: libervia/backend/plugins/plugin_sec_pubsub

comparison libervia/backend/plugins/plugin_sec_pubsub_signing.py @ 4071:4b842c1fb686

refactoring: renamed `sat` package to `libervia.backend`

author	Goffi <goffi@goffi.org>
date	Fri, 02 Jun 2023 11:49:51 +0200
parents	sat/plugins/plugin_sec_pubsub_signing.py@524856bd7b19
children

comparison

equal deleted inserted replaced

-:d10748475025
+:4b842c1fb686
+#!/usr/bin/env python3
+# Libervia plugin for Pubsub Items Signature
+# Copyright (C) 2009-2022 Jérôme Poisson (goffi@goffi.org)
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+import base64
+import time
+from typing import Any, Dict, List, Optional
+from lxml import etree
+import shortuuid
+from twisted.internet import defer
+from twisted.words.protocols.jabber import jid, xmlstream
+from twisted.words.xish import domish
+from wokkel import disco, iwokkel
+from wokkel import pubsub
+from zope.interface import implementer
+from libervia.backend.core import exceptions
+from libervia.backend.core.constants import Const as C
+from libervia.backend.core.core_types import SatXMPPEntity
+from libervia.backend.core.i18n import _
+from libervia.backend.core.log import getLogger
+from libervia.backend.tools import utils
+from libervia.backend.tools.common import data_format
+from .plugin_xep_0373 import VerificationFailed
+log = getLogger(__name__)
+IMPORT_NAME = "pubsub-signing"
+PLUGIN_INFO = {
+C.PI_NAME: "Pubsub Signing",
+C.PI_IMPORT_NAME: IMPORT_NAME,
+C.PI_TYPE: C.PLUG_TYPE_XEP,
+C.PI_MODES: C.PLUG_MODE_BOTH,
+C.PI_PROTOCOLS: [],
+C.PI_DEPENDENCIES: ["XEP-0060", "XEP-0373", "XEP-0470"],
+C.PI_MAIN: "PubsubSigning",
+C.PI_HANDLER: "yes",
+C.PI_DESCRIPTION: _(
+"""Pubsub Signature can be used to strongly authenticate a pubsub item"""
+),
+}
+NS_PUBSUB_SIGNING = "urn:xmpp:pubsub-signing:0"
+NS_PUBSUB_SIGNING_OPENPGP = "urn:xmpp:pubsub-signing:openpgp:0"
+class PubsubSigning:
+namespace = NS_PUBSUB_SIGNING
+def __init__(self, host):
+log.info(_("Pubsub Signing plugin initialization"))
+host.register_namespace("pubsub-signing", NS_PUBSUB_SIGNING)
+self.host = host
+self._p = host.plugins["XEP-0060"]
+self._ox = host.plugins["XEP-0373"]
+self._a = host.plugins["XEP-0470"]
+self._a.register_attachment_handler(
+"signature", NS_PUBSUB_SIGNING, self.signature_get, self.signature_set
+)
+host.trigger.add("XEP-0060_publish", self._publish_trigger)
+host.bridge.add_method(
+"ps_signature_check",
+".plugin",
+in_sign="sssss",
+out_sign="s",
+method=self._check,
+async_=True,
+)
+def get_handler(self, client):
+return PubsubSigning_Handler()
+def get_data_to_sign(
+self,
+item_elt: domish.Element,
+to_jid: jid.JID,
+timestamp: float,
+signer: str,
+) -> bytes:
+"""Generate the wrapper element, normalize, serialize and return it"""
+# we remove values which must not be in the serialised data
+item_id = item_elt.attributes.pop("id")
+item_publisher = item_elt.attributes.pop("publisher", None)
+item_parent = item_elt.parent
+# we need to be sure that item element namespace is right
+item_elt.uri = item_elt.defaultUri = pubsub.NS_PUBSUB
+sign_data_elt = domish.Element((NS_PUBSUB_SIGNING, "sign-data"))
+to_elt = sign_data_elt.addElement("to")
+to_elt["jid"] = to_jid.userhost()
+time_elt = sign_data_elt.addElement("time")
+time_elt["stamp"] = utils.xmpp_date(timestamp)
+sign_data_elt.addElement("signer", content=signer)
+sign_data_elt.addChild(item_elt)
+# FIXME: xml_tools.domish_elt_2_et_elt must be used once implementation is
+#   complete. For now serialisation/deserialisation is more secure.
+# et_sign_data_elt = xml_tools.domish_elt_2_et_elt(sign_data_elt, True)
+et_sign_data_elt = etree.fromstring(sign_data_elt.toXml())
+to_sign = etree.tostring(
+et_sign_data_elt,
+method="c14n2",
+with_comments=False,
+strip_text=True
+)
+# the data to sign is serialised, we cna restore original values
+item_elt["id"] = item_id
+if item_publisher is not None:
+item_elt["publisher"] = item_publisher
+item_elt.parent = item_parent
+return to_sign
+def _check(
+self,
+service: str,
+node: str,
+item_id: str,
+signature_data_s: str,
+profile_key: str,
+) -> defer.Deferred:
+d = defer.ensureDeferred(
+self.check(
+self.host.get_client(profile_key),
+jid.JID(service),
+node,
+item_id,
+data_format.deserialise(signature_data_s)
+)
+)
+d.addCallback(data_format.serialise)
+return d
+async def check(
+self,
+client: SatXMPPEntity,
+service: jid.JID,
+node: str,
+item_id: str,
+signature_data: Dict[str, Any],
+) -> Dict[str, Any]:
+items, __ = await self._p.get_items(
+client, service, node, item_ids=[item_id]
+)
+if not items != 1:
+raise exceptions.NotFound(
+f"target item not found for {item_id!r} at {node!r} for {service}"
+)
+item_elt = items[0]
+timestamp = signature_data["timestamp"]
+signers = signature_data["signers"]
+if not signers:
+raise ValueError("we must have at least one signer to check the signature")
+if len(signers) > 1:
+raise NotImplemented("multiple signers are not supported yet")
+signer = jid.JID(signers[0])
+signature = base64.b64decode(signature_data["signature"])
+verification_keys = {
+k for k in await self._ox.import_all_public_keys(client, signer)
+if client.gpg_provider.can_sign(k)
+}
+signed_data = self.get_data_to_sign(item_elt, service, timestamp, signer.full())
+try:
+client.gpg_provider.verify_detached(signed_data, signature, verification_keys)
+except VerificationFailed:
+validated = False
+else:
+validated = True
+trusts = {
+k.fingerprint: (await self._ox.get_trust(client, k, signer)).value.lower()
+for k in verification_keys
+}
+return {
+"signer": signer.full(),
+"validated": validated,
+"trusts": trusts,
+}
+def signature_get(
+self,
+client: SatXMPPEntity,
+attachments_elt: domish.Element,
+data: Dict[str, Any],
+) -> None:
+try:
+signature_elt = next(
+attachments_elt.elements(NS_PUBSUB_SIGNING, "signature")
+)
+except StopIteration:
+pass
+else:
+time_elts = list(signature_elt.elements(NS_PUBSUB_SIGNING, "time"))
+if len(time_elts) != 1:
+raise exceptions.DataError("only a single <time/> element is allowed")
+try:
+timestamp = utils.parse_xmpp_date(time_elts[0]["stamp"])
+except (KeyError, exceptions.ParsingError):
+raise exceptions.DataError(
+"invalid time element: {signature_elt.toXml()}"
+)
+signature_data: Dict[str, Any] = {
+"timestamp": timestamp,
+"signers": [
+str(s) for s in signature_elt.elements(NS_PUBSUB_SIGNING, "signer")
+]
+}
+# FIXME: only OpenPGP signature is available for now, to be updated if and
+#   when more algorithms are available.
+sign_elt = next(
+signature_elt.elements(NS_PUBSUB_SIGNING_OPENPGP, "sign"),
+None
+)
+if sign_elt is None:
+log.warning(
+"no known signature profile element found, ignoring signature: "
+f"{signature_elt.toXml()}"
+)
+return
+else:
+signature_data["signature"] = str(sign_elt)
+data["signature"] = signature_data
+async def signature_set(
+self,
+client: SatXMPPEntity,
+attachments_data: Dict[str, Any],
+former_elt: Optional[domish.Element]
+) -> Optional[domish.Element]:
+signature_data = attachments_data["extra"].get("signature")
+if signature_data is None:
+return former_elt
+elif signature_data:
+item_elt = signature_data.get("item_elt")
+service = jid.JID(attachments_data["service"])
+if item_elt is None:
+node = attachments_data["node"]
+item_id = attachments_data["id"]
+items, __ = await self._p.get_items(
+client, service, node, item_ids=[item_id]
+)
+if not items != 1:
+raise exceptions.NotFound(
+f"target item not found for {item_id!r} at {node!r} for {service}"
+)
+item_elt = items[0]
+signer = signature_data.get("signer") or client.jid.userhost()
+timestamp = time.time()
+timestamp_xmpp = utils.xmpp_date(timestamp)
+to_sign = self.get_data_to_sign(item_elt, service, timestamp, signer)
+signature_elt = domish.Element(
+(NS_PUBSUB_SIGNING, "signature"),
+)
+time_elt = signature_elt.addElement("time")
+time_elt["stamp"] = timestamp_xmpp
+signature_elt.addElement("signer", content=signer)
+sign_elt = signature_elt.addElement((NS_PUBSUB_SIGNING_OPENPGP, "sign"))
+signing_keys = {
+k for k in self._ox.list_secret_keys(client)
+if client.gpg_provider.can_sign(k.public_key)
+}
+# the base64 encoded signature itself
+sign_elt.addContent(
+base64.b64encode(
+client.gpg_provider.sign_detached(to_sign, signing_keys)
+).decode()
+)
+return signature_elt
+else:
+return None
+async def _publish_trigger(
+self,
+client: SatXMPPEntity,
+service: jid.JID,
+node: str,
+items: Optional[List[domish.Element]],
+options: Optional[dict],
+sender: jid.JID,
+extra: Dict[str, Any]
+) -> bool:
+if not items or not extra.get("signed"):
+return True
+for item_elt in items:
+# we need an ID to find corresponding attachment node, and so to sign an item
+if not item_elt.hasAttribute("id"):
+item_elt["id"] = shortuuid.uuid()
+await self._a.set_attachements(
+client,
+{
+"service": service.full(),
+"node": node,
+"id": item_elt["id"],
+"extra": {
+"signature": {
+"item_elt": item_elt,
+"signer": sender.userhost(),
+}
+}
+}
+)
+return True
+@implementer(iwokkel.IDisco)
+class PubsubSigning_Handler(xmlstream.XMPPHandler):
+def getDiscoInfo(self, requestor, service, nodeIdentifier=""):
+return [disco.DiscoFeature(NS_PUBSUB_SIGNING)]
+def getDiscoItems(self, requestor, service, nodeIdentifier=""):
+return []

Mercurial > libervia-backend

comparison libervia/backend/plugins/plugin_sec_pubsub_signing.py @ 4071:4b842c1fb686