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Split error messages from event decryption

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master
Nicolas Werner 4 years ago
parent dbaddb0165
commit 1f9215a5be
3 changed files with 146 additions and 82 deletions
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  1. 47
      src/Olm.cpp
  2. 24
      src/Olm.h
  3. 157
      src/timeline/EventStore.cpp

47
src/Olm.cpp
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@ -3,6 +3,7 @@
#include "Olm.h"
#include "Cache.h"
#include "Cache_p.h"
#include "Logging.h"
#include "MatrixClient.h"
#include "Utils.h"
@ -551,4 +552,50 @@ send_megolm_key_to_device(const std::string &user_id,
});
}
DecryptionResult
decryptEvent(const MegolmSessionIndex &index,
const mtx::events::EncryptedEvent<mtx::events::msg::Encrypted> &event)
{
try {
if (!cache::client()->inboundMegolmSessionExists(index)) {
return {DecryptionErrorCode::MissingSession, std::nullopt, std::nullopt};
}
} catch (const lmdb::error &e) {
return {DecryptionErrorCode::DbError, e.what(), std::nullopt};
}
// TODO: Lookup index,event_id,origin_server_ts tuple for replay attack errors
// TODO: Verify sender_key
std::string msg_str;
try {
auto session = cache::client()->getInboundMegolmSession(index);
auto res = olm::client()->decrypt_group_message(session, event.content.ciphertext);
msg_str = std::string((char *)res.data.data(), res.data.size());
} catch (const lmdb::error &e) {
return {DecryptionErrorCode::DbError, e.what(), std::nullopt};
} catch (const mtx::crypto::olm_exception &e) {
return {DecryptionErrorCode::DecryptionFailed, e.what(), std::nullopt};
}
// Add missing fields for the event.
json body = json::parse(msg_str);
body["event_id"] = event.event_id;
body["sender"] = event.sender;
body["origin_server_ts"] = event.origin_server_ts;
body["unsigned"] = event.unsigned_data;
// relations are unencrypted in content...
if (json old_ev = event; old_ev["content"].count("m.relates_to") != 0)
body["content"]["m.relates_to"] = old_ev["content"]["m.relates_to"];
mtx::events::collections::TimelineEvent te;
try {
mtx::events::collections::from_json(body, te);
} catch (std::exception &e) {
return {DecryptionErrorCode::ParsingFailed, e.what(), std::nullopt};
}
return {std::nullopt, std::nullopt, std::move(te.data)};
}
} // namespace olm

24
src/Olm.h
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@ -7,10 +7,30 @@
#include <mtx/events/encrypted.hpp>
#include <mtxclient/crypto/client.hpp>
#include <CacheCryptoStructs.h>
constexpr auto OLM_ALGO = "m.olm.v1.curve25519-aes-sha2";
namespace olm {
enum class DecryptionErrorCode
{
MissingSession, // Session was not found, retrieve from backup or request from other devices
// and try again
DbError, // DB read failed
DecryptionFailed, // libolm error
ParsingFailed, // Failed to parse the actual event
ReplayAttack, // Megolm index reused
UnknownFingerprint, // Unknown device Fingerprint
};
struct DecryptionResult
{
std::optional<DecryptionErrorCode> error;
std::optional<std::string> error_message;
std::optional<mtx::events::collections::TimelineEvents> event;
};
struct OlmMessage
{
std::string sender_key;
@ -65,6 +85,10 @@ encrypt_group_message(const std::string &room_id,
const std::string &device_id,
nlohmann::json body);
DecryptionResult
decryptEvent(const MegolmSessionIndex &index,
const mtx::events::EncryptedEvent<mtx::events::msg::Encrypted> &event);
void
mark_keys_as_published();

157
src/timeline/EventStore.cpp
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@ -379,103 +379,96 @@ EventStore::decryptEvent(const IdIndex &idx,
index.session_id = e.content.session_id;
index.sender_key = e.content.sender_key;
mtx::events::RoomEvent<mtx::events::msg::Notice> dummy;
dummy.origin_server_ts = e.origin_server_ts;
dummy.event_id = e.event_id;
dummy.sender = e.sender;
dummy.content.body =
tr("-- Encrypted Event (No keys found for decryption) --",
"Placeholder, when the message was not decrypted yet or can't be decrypted.")
.toStdString();
auto asCacheEntry = [&idx](mtx::events::collections::TimelineEvents &&event) {
auto event_ptr = new mtx::events::collections::TimelineEvents(std::move(event));
decryptedEvents_.insert(idx, event_ptr);
return event_ptr;
};
try {
if (!cache::client()->inboundMegolmSessionExists(index)) {
auto decryptionResult = olm::decryptEvent(index, e);
if (decryptionResult.error) {
mtx::events::RoomEvent<mtx::events::msg::Notice> dummy;
dummy.origin_server_ts = e.origin_server_ts;
dummy.event_id = e.event_id;
dummy.sender = e.sender;
switch (*decryptionResult.error) {
case olm::DecryptionErrorCode::MissingSession:
dummy.content.body =
tr("-- Encrypted Event (No keys found for decryption) --",
"Placeholder, when the message was not decrypted yet or can't be "
"decrypted.")
.toStdString();
nhlog::crypto()->info("Could not find inbound megolm session ({}, {}, {})",
index.room_id,
index.session_id,
e.sender);
// TODO: request megolm session_id & session_key from the sender.
return asCacheEntry(std::move(dummy));
// TODO: Check if this actually works and look in key backup
olm::send_key_request_for(room_id_, e);
break;
case olm::DecryptionErrorCode::DbError:
nhlog::db()->critical(
"failed to retrieve megolm session with index ({}, {}, {})",
index.room_id,
index.session_id,
index.sender_key,
decryptionResult.error_message.value_or(""));
dummy.content.body =
tr("-- Decryption Error (failed to retrieve megolm keys from db) --",
"Placeholder, when the message can't be decrypted, because the DB "
"access "
"failed.")
.toStdString();
break;
case olm::DecryptionErrorCode::DecryptionFailed:
nhlog::crypto()->critical(
"failed to decrypt message with index ({}, {}, {}): {}",
index.room_id,
index.session_id,
index.sender_key,
decryptionResult.error_message.value_or(""));
dummy.content.body =
tr("-- Decryption Error (%1) --",
"Placeholder, when the message can't be decrypted. In this case, the "
"Olm "
"decrytion returned an error, which is passed as %1.")
.arg(
QString::fromStdString(decryptionResult.error_message.value_or("")))
.toStdString();
break;
case olm::DecryptionErrorCode::ParsingFailed:
dummy.content.body =
tr("-- Encrypted Event (Unknown event type) --",
"Placeholder, when the message was decrypted, but we couldn't parse "
"it, because "
"Nheko/mtxclient don't support that event type yet.")
.toStdString();
break;
case olm::DecryptionErrorCode::ReplayAttack:
nhlog::crypto()->critical(
"Reply attack while decryptiong event {} in room {} from {}!",
e.event_id,
room_id_,
index.sender_key);
dummy.content.body =
tr("-- Reply attack! This message index was reused! --").toStdString();
break;
case olm::DecryptionErrorCode::UnknownFingerprint:
// TODO: don't fail, just show in UI.
nhlog::crypto()->critical("Message by unverified fingerprint {}",
index.sender_key);
dummy.content.body =
tr("-- Message by unverified device! --").toStdString();
break;
}
} catch (const lmdb::error &e) {
nhlog::db()->critical("failed to check megolm session's existence: {}", e.what());
dummy.content.body = tr("-- Decryption Error (failed to communicate with DB) --",
"Placeholder, when the message can't be decrypted, because "
"the DB access failed when trying to lookup the session.")
.toStdString();
return asCacheEntry(std::move(dummy));
}
std::string msg_str;
try {
auto session = cache::client()->getInboundMegolmSession(index);
auto res = olm::client()->decrypt_group_message(session, e.content.ciphertext);
msg_str = std::string((char *)res.data.data(), res.data.size());
} catch (const lmdb::error &e) {
nhlog::db()->critical("failed to retrieve megolm session with index ({}, {}, {})",
index.room_id,
index.session_id,
index.sender_key,
e.what());
dummy.content.body =
tr("-- Decryption Error (failed to retrieve megolm keys from db) --",
"Placeholder, when the message can't be decrypted, because the DB access "
"failed.")
.toStdString();
return asCacheEntry(std::move(dummy));
} catch (const mtx::crypto::olm_exception &e) {
nhlog::crypto()->critical("failed to decrypt message with index ({}, {}, {}): {}",
index.room_id,
index.session_id,
index.sender_key,
e.what());
dummy.content.body =
tr("-- Decryption Error (%1) --",
"Placeholder, when the message can't be decrypted. In this case, the Olm "
"decrytion returned an error, which is passed as %1.")
.arg(e.what())
.toStdString();
return asCacheEntry(std::move(dummy));
}
// Add missing fields for the event.
json body = json::parse(msg_str);
body["event_id"] = e.event_id;
body["sender"] = e.sender;
body["origin_server_ts"] = e.origin_server_ts;
body["unsigned"] = e.unsigned_data;
// relations are unencrypted in content...
if (json old_ev = e; old_ev["content"].count("m.relates_to") != 0)
body["content"]["m.relates_to"] = old_ev["content"]["m.relates_to"];
json event_array = json::array();
event_array.push_back(body);
std::vector<mtx::events::collections::TimelineEvents> temp_events;
mtx::responses::utils::parse_timeline_events(event_array, temp_events);
if (temp_events.size() == 1) {
auto encInfo = mtx::accessors::file(temp_events[0]);
if (encInfo)
emit newEncryptedImage(encInfo.value());
return asCacheEntry(std::move(temp_events[0]));
}
auto encInfo = mtx::accessors::file(decryptionResult.event.value());
if (encInfo)
emit newEncryptedImage(encInfo.value());
dummy.content.body =
tr("-- Encrypted Event (Unknown event type) --",
"Placeholder, when the message was decrypted, but we couldn't parse it, because "
"Nheko/mtxclient don't support that event type yet.")
.toStdString();
return asCacheEntry(std::move(dummy));
return asCacheEntry(std::move(decryptionResult.event.value()));
}
mtx::events::collections::TimelineEvents *

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