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* io/crypto: Move tls premature termination handling into QIO layerPeter Xu2025-10-031-7/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | QCryptoTLSSession allows TLS premature termination in two cases, one of the case is when the channel shutdown() is invoked on READ side. It's possible the shutdown() happened after the read thread blocked at gnutls_record_recv(). In this case, we should allow the premature termination to happen. The problem is by the time qcrypto_tls_session_read() was invoked, tioc->shutdown may not have been set, so this may instead be treated as an error if there is concurrent shutdown() calls. To allow the flag to reflect the latest status of tioc->shutdown, move the check upper into the QIOChannel level, so as to read the flag only after QEMU gets an GNUTLS_E_PREMATURE_TERMINATION. When at it, introduce qio_channel_tls_allow_premature_termination() helper to make the condition checks easier to read. When doing so, change the qatomic_load_acquire() to qatomic_read(): here we don't need any ordering of memory accesses, but reading a flag. qatomic_read() would suffice because it guarantees fetching from memory. Nothing else we should need to order on memory access. This patch will fix a qemu qtest warning when running the preempt tls test, reporting premature termination: QTEST_QEMU_BINARY=./qemu-system-x86_64 ./tests/qtest/migration-test --full -r /x86_64/migration/postcopy/preempt/tls/psk ... qemu-kvm: Cannot read from TLS channel: The TLS connection was non-properly terminated. ... In this specific case, the error was set by postcopy_preempt_thread, which normally will be concurrently shutdown()ed by the main thread. Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Juraj Marcin <jmarcin@redhat.com> Reviewed-by: Fabiano Rosas <farosas@suse.de> Link: https://lore.kernel.org/r/20250918203937.200833-2-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com>
* crypto: implement workaround for GNUTLS thread safety problemsDaniel P. Berrangé2025-07-221-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When TLS 1.3 is negotiated on a TLS session, GNUTLS will perform automatic rekeying of the session after 16 million records. This is done for all algorithms except CHACHA20_POLY1305 which does not require rekeying. Unfortunately the rekeying breaks GNUTLS' promise that it is safe to use a gnutls_session_t object concurrently from multiple threads if they are exclusively calling gnutls_record_send/recv. This patch implements a workaround for QEMU that adds a mutex lock around any gnutls_record_send/recv call to serialize execution within GNUTLS code. When GNUTLS calls into the push/pull functions we can release the lock so the OS level I/O calls can at least have some parallelism. The big downside of this is that the actual encryption/decryption code is fully serialized, which will halve performance of that cipher operations if two threads are contending. The workaround is not enabled by default, since most use of GNUTLS in QEMU does not tickle the problem, only non-multifd migration with a return path open is affected. Fortunately the migration code also won't trigger the halving of performance, since only the outbound channel diretion needs to sustain high data rates, the inbound direction is low volume. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Fabiano Rosas <farosas@suse.de> Link: https://lore.kernel.org/qemu-devel/20250718150514.2635338-2-berrange@redhat.com [add stub for qcrypto_tls_session_require_thread_safety; fix unused var] Signed-off-by: Fabiano Rosas <farosas@suse.de>
* crypto: Remove qcrypto_tls_session_get_handshake_statusFabiano Rosas2025-02-141-24/+8
| | | | | | | | | | | | | | | | The correct way of calling qcrypto_tls_session_handshake() requires calling qcrypto_tls_session_get_handshake_status() right after it so there's no reason to have a separate method. Refactor qcrypto_tls_session_handshake() to inform the status in its own return value and alter the callers accordingly. No functional change. Suggested-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Acked-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Fabiano Rosas <farosas@suse.de>
* crypto: Allow gracefully ending the TLS sessionFabiano Rosas2025-02-141-0/+22
| | | | | | | | | | | | | | | | | | | QEMU's TLS session code provides no way to call gnutls_bye() to terminate a TLS session. Callers of qcrypto_tls_session_read() can choose to ignore a GNUTLS_E_PREMATURE_TERMINATION error by setting the gracefulTermination argument. The QIOChannelTLS ignores the premature termination error whenever shutdown() has already been issued. This was found to be not enough for the migration code because shutdown() might not have been issued before the connection is terminated. Add support for calling gnutls_bye() in the tlssession layer so users of QIOChannelTLS can clearly identify the end of a TLS session. Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Acked-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Fabiano Rosas <farosas@suse.de>
* crypto: propagate errors from TLS session I/O callbacksDaniel P. Berrangé2024-07-241-2/+8
| | | | | | | | | | | | | | | GNUTLS doesn't know how to perform I/O on anything other than plain FDs, so the TLS session provides it with some I/O callbacks. The GNUTLS API design requires these callbacks to return a unix errno value, which means we're currently loosing the useful QEMU "Error" object. This changes the I/O callbacks in QEMU to stash the "Error" object in the QCryptoTLSSession class, and fetch it when seeing an I/O error returned from GNUTLS, thus preserving useful error messages. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
* crypto: push error reporting into TLS session I/O APIsDaniel P. Berrangé2024-07-241-4/+19
| | | | | | | | | | | | | The current TLS session I/O APIs just return a synthetic errno value on error, which has been translated from a gnutls error value. This looses a large amount of valuable information that distinguishes different scenarios. Pushing population of the "Error *errp" object into the TLS session I/O APIs gives more detailed error information. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
* crypto: TLS: introduce `check_pending`Antoine Damhet2023-02-151-0/+11
| | | | | | | | | The new `qcrypto_tls_session_check_pending` function allows the caller to know if data have already been consumed from the backend and is already available. Signed-off-by: Antoine Damhet <antoine.damhet@shadow.tech> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
* crypto: Fix typo in QCryptoTLSSession's <example> commentMarkus Armbruster2019-12-181-1/+1
| | | | | | | | Cc: "Daniel P. Berrangé" <berrange@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20191204093625.14836-3-armbru@redhat.com> Acked-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* crypto: define cleanup functions for use with g_autoptrDaniel P. Berrangé2019-08-221-0/+2
| | | | | | | | | | Allow crypto structs to be used with g_autoptr, avoiding the need to explicitly call XXX_free() functions when variables go out of scope on the stack. Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
* crypto: Fix LGPL information in the file headersThomas Huth2019-07-191-1/+1
| | | | | | | | | It's either "GNU *Library* General Public License version 2" or "GNU Lesser General Public License version *2.1*", but there was no "version 2.0" of the "Lesser" license. So assume that version 2.1 is meant here. Signed-off-by: Thomas Huth <thuth@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
* Clean up header guards that don't match their file nameMarkus Armbruster2016-07-121-3/+3
| | | | | | | | | | | | Header guard symbols should match their file name to make guard collisions less likely. Offenders found with scripts/clean-header-guards.pl -vn. Cleaned up with scripts/clean-header-guards.pl, followed by some renaming of new guard symbols picked by the script to better ones. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net>
* crypto: fix description of @errp parameter initializationDaniel P. Berrange2016-02-011-4/+4
| | | | | | | The "Error **errp" parameters must be NULL initialized not uninitialized. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
* crypto: Fix typo in exampleEric Blake2016-01-111-1/+1
| | | | | | | | | The example code wouldn't even compile, since it did not use a consistent spelling for the Error ** parameter. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
* crypto: introduce new module for handling TLS sessionsDaniel P. Berrange2015-09-151-0/+322
Introduce a QCryptoTLSSession object that will encapsulate all the code for setting up and using a client/sever TLS session. This isolates the code which depends on the gnutls library, avoiding #ifdefs in the rest of the codebase, as well as facilitating any possible future port to other TLS libraries, if desired. It makes use of the previously defined QCryptoTLSCreds object to access credentials to use with the session. It also includes further unit tests to validate the correctness of the TLS session handshake and certificate validation. This is functionally equivalent to the current TLS session handling code embedded in the VNC server, and will obsolete it. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>