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Type:
Task
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Resolution: Fixed
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Internal Code
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None
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Service Arch
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Fully Compatible
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Service Arch 2023-01-23, Service Arch 2023-02-06, Service Arch 2023-02-20, Service Arch 2023-03-06, Service Arch 2023-10-16, Service Arch 2023-10-30, Service Arch 2023-11-13, Service Arch 2023-11-27, Service Arch 2023-12-11, Service Arch 2023-12-25
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120
Other threads may use Session::end() to interrupt ongoing networking and close the session. For example, ServiceEntryPointImpl (responsible for managing ingress sessions) calls into SessionWorkflow::terminate as part of its shutdown process. That will result in calling Session::end:
void SessionWorkflow::Impl::terminate() { if (_isTerminated.swap(true)) return; session()->end(); } ... void AsioTransportLayer::AsioSession::end() { if (getSocket().is_open()) { std::error_code ec; getSocket().shutdown(GenericSocket::shutdown_both, ec); if ((ec) && (ec != asio::error::not_connected)) { LOGV2_ERROR(23841, "Error shutting down socket: {error}", "Error shutting down socket", "error"_attr = ec.message()); } } } ... auto AsioTransportLayer::AsioSession::getSocket() -> GenericSocket& { #ifdef MONGO_CONFIG_SSL if (_sslSocket) { return static_cast<GenericSocket&>(_sslSocket->lowest_layer()); } #endif return _socket; }
As shown above, and when SSL is enabled and we use AsioSession, terminating a session from another thread requires accessing _sslSocket and _socket members of AsioSession. This may happen when the thread owning the Session is performing an SSL handshake (as part of the initial read on the socket):
std::unique_ptr<SessionWorkflow::Impl::WorkItem> SessionWorkflow::Impl::_receiveRequest() { try { auto msg = uassertStatusOK([&] { MONGO_IDLE_THREAD_BLOCK; return session()->sourceMessage(); }()); invariant(!msg.empty()); return std::make_unique<WorkItem>(this, std::move(msg)); } catch (const DBException& ex) { ... } } ... StatusWith<Message> AsioTransportLayer::AsioSession::sourceMessage() noexcept try { ensureSync(); return sourceMessageImpl().getNoThrow(); } catch (const DBException& ex) { return ex.toStatus(); }
The current implementation for the handshake performs the following, creating a potential read after write data-race on the _sslSocket member:
template <typename MutableBufferSequence> Future<bool> AsioTransportLayer::AsioSession::maybeHandshakeSSLForIngress( const MutableBufferSequence& buffer) { ... _sslSocket.emplace(std::move(_socket), *_sslContext->ingress, ""); ... }
The goal of this ticket is to ensure terminating sessions is a thread-safe operation, regardless of the state of the Session object. For context, SERVER-62970 addressed a similar issue for SSL handshake on egress connections.
- related to
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- Backlog
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SERVER-83933 Move AsioSession ingress initialization steps before startSession
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- Backlog
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