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Remove sender key from megolm session index

Browse source 
implements MSC3700

see https://github.com/matrix-org/matrix-spec-proposals/pull/3700
This commit is contained in:
Nicolas Werner 2022-04-08 01:53:00 +02:00
parent a5e0e47a81
commit 66b7ff639c
4 changed files with 102 additions and 41 deletions
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48
src/encryption/Olm.cpp
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@ -614,6 +614,7 @@ encrypt_group_message(const std::string &room_id, const std::string &device_id,
session_data.message_index = 0;
session_data.timestamp = QDateTime::currentMSecsSinceEpoch();
session_data.sender_claimed_ed25519_key = olm::client()->identity_keys().ed25519;
session_data.sender_key = olm::client()->identity_keys().curve25519;
sendSessionTo.clear();
@ -635,7 +636,6 @@ encrypt_group_message(const std::string &room_id, const std::string &device_id,
MegolmSessionIndex index;
index.room_id = room_id;
index.session_id = session_id;
index.sender_key = olm::client()->identity_keys().curve25519;
auto megolm_session = olm::client()->init_inbound_group_session(session_key);
backup_session_key(index, session_data, megolm_session);
cache::saveInboundMegolmSession(index, std::move(megolm_session), session_data);
@ -734,12 +734,12 @@ create_inbound_megolm_session(const mtx::events::DeviceEvent<mtx::events::msg::R
MegolmSessionIndex index;
index.room_id = roomKey.content.room_id;
index.session_id = roomKey.content.session_id;
index.sender_key = sender_key;
try {
GroupSessionData data{};
data.forwarding_curve25519_key_chain = {sender_key};
data.sender_claimed_ed25519_key = sender_ed25519;
data.sender_key = sender_key;
auto megolm_session =
olm::client()->init_inbound_group_session(roomKey.content.session_key);
@ -766,7 +766,6 @@ import_inbound_megolm_session(
MegolmSessionIndex index;
index.room_id = roomKey.content.room_id;
index.session_id = roomKey.content.session_id;
index.sender_key = roomKey.content.sender_key;
try {
auto megolm_session =
@ -775,6 +774,7 @@ import_inbound_megolm_session(
GroupSessionData data{};
data.forwarding_curve25519_key_chain = roomKey.content.forwarding_curve25519_key_chain;
data.sender_claimed_ed25519_key = roomKey.content.sender_claimed_ed25519_key;
data.sender_key = roomKey.content.sender_key;
// may have come from online key backup, so we can't trust it...
data.trusted = false;
// if we got it forwarded from the sender, assume it is trusted. They may still have
@ -832,7 +832,7 @@ backup_session_key(const MegolmSessionIndex &idx,
sessionData.algorithm = mtx::crypto::MEGOLM_ALGO;
sessionData.forwarding_curve25519_key_chain = data.forwarding_curve25519_key_chain;
sessionData.sender_claimed_keys["ed25519"] = data.sender_claimed_ed25519_key;
sessionData.sender_key = idx.sender_key;
sessionData.sender_key = data.sender_key;
sessionData.session_key = mtx::crypto::export_session(session.get(), -1);
auto encrypt_session = mtx::crypto::encrypt_session(sessionData, public_key);
@ -920,11 +920,11 @@ lookup_keybackup(const std::string room, const std::string session_id)
MegolmSessionIndex index;
index.room_id = room;
index.session_id = session_id;
index.sender_key = session.sender_key;
GroupSessionData data{};
data.forwarding_curve25519_key_chain = session.forwarding_curve25519_key_chain;
data.sender_claimed_ed25519_key = session.sender_claimed_keys["ed25519"];
data.sender_key = session.sender_key;
// online key backup can't be trusted, because anyone can upload to it.
data.trusted = false;
@ -982,8 +982,8 @@ send_key_request_for(mtx::events::EncryptedEvent<mtx::events::msg::Encrypted> e,
nhlog::crypto()->debug("m.room_key_request: {}", json(request).dump(2));
std::map<mtx::identifiers::User, std::map<std::string, decltype(request)>> body;
body[mtx::identifiers::parse<mtx::identifiers::User>(e.sender)][e.content.device_id] = request;
body[http::client()->user_id()]["*"] = request;
body[mtx::identifiers::parse<mtx::identifiers::User>(e.sender)]["*"] = request;
body[http::client()->user_id()]["*"] = request;
http::client()->send_to_device(
http::client()->generate_txn_id(), body, [e](mtx::http::RequestErr err) {
@ -1011,24 +1011,10 @@ handle_key_request_message(const mtx::events::DeviceEvent<mtx::events::msg::KeyR
return;
}
// Check if we were the sender of the session being requested (unless it is actually us
// requesting the session).
if (req.sender != http::client()->user_id().to_string() &&
req.content.sender_key != olm::client()->identity_keys().curve25519) {
nhlog::crypto()->debug(
"ignoring key request {} because we did not create the requested session: "
"\nrequested({}) ours({})",
req.content.request_id,
req.content.sender_key,
olm::client()->identity_keys().curve25519);
return;
}
// Check that the requested session_id and the one we have saved match.
MegolmSessionIndex index{};
index.room_id = req.content.room_id;
index.session_id = req.content.session_id;
index.sender_key = req.content.sender_key;
// Check if we have the keys for the requested session.
auto sessionData = cache::getMegolmSessionData(index);
@ -1037,6 +1023,19 @@ handle_key_request_message(const mtx::events::DeviceEvent<mtx::events::msg::KeyR
return;
}
// Check if we were the sender of the session being requested (unless it is actually us
// requesting the session).
if (req.sender != http::client()->user_id().to_string() &&
sessionData->sender_key != olm::client()->identity_keys().curve25519) {
nhlog::crypto()->debug(
"ignoring key request {} because we did not create the requested session: "
"\nrequested({}) ours({})",
req.content.request_id,
sessionData->sender_key,
olm::client()->identity_keys().curve25519);
return;
}
const auto session = cache::getInboundMegolmSession(index);
if (!session) {
nhlog::crypto()->warn("No session with id {} in db", req.content.session_id);
@ -1098,7 +1097,7 @@ handle_key_request_message(const mtx::events::DeviceEvent<mtx::events::msg::KeyR
forward_key.room_id = index.room_id;
forward_key.session_id = index.session_id;
forward_key.session_key = session_key;
forward_key.sender_key = index.sender_key;
forward_key.sender_key = sessionData->sender_key;
// TODO(Nico): Figure out if this is correct
forward_key.sender_claimed_ed25519_key = sessionData->sender_claimed_ed25519_key;
@ -1196,8 +1195,9 @@ calculate_trust(const std::string &user_id, const MegolmSessionIndex &index)
auto megolmData = cache::client()->getMegolmSessionData(index);
crypto::Trust trustlevel = crypto::Trust::Unverified;
if (megolmData && megolmData->trusted && status.verified_device_keys.count(index.sender_key))
trustlevel = status.verified_device_keys.at(index.sender_key);
if (megolmData && megolmData->trusted &&
status.verified_device_keys.count(megolmData->sender_key))
trustlevel = status.verified_device_keys.at(megolmData->sender_key);
return trustlevel;
}