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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>
377 lines
13 KiB
C
377 lines
13 KiB
C
/*
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* QEMU crypto TLS session support
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*
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* Copyright (c) 2015 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef QCRYPTO_TLSSESSION_H
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#define QCRYPTO_TLSSESSION_H
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#include "crypto/tlscreds.h"
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/**
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* QCryptoTLSSession:
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*
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* The QCryptoTLSSession object encapsulates the
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* logic to integrate with a TLS providing library such
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* as GNUTLS, to setup and run TLS sessions.
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*
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* The API is designed such that it has no assumption about
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* the type of transport it is running over. It may be a
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* traditional TCP socket, or something else entirely. The
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* only requirement is a full-duplex stream of some kind.
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*
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* <example>
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* <title>Using TLS session objects</title>
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* <programlisting>
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* static ssize_t mysock_send(const char *buf, size_t len,
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* void *opaque)
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* {
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* int fd = GPOINTER_TO_INT(opaque);
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*
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* return write(*fd, buf, len);
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* }
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*
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* static ssize_t mysock_recv(const char *buf, size_t len,
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* void *opaque)
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* {
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* int fd = GPOINTER_TO_INT(opaque);
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*
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* return read(*fd, buf, len);
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* }
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*
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* static int mysock_run_tls(int sockfd,
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* QCryptoTLSCreds *creds,
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* Error **errp)
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* {
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* QCryptoTLSSession *sess;
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*
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* sess = qcrypto_tls_session_new(creds,
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* "vnc.example.com",
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* NULL,
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* QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT,
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* errp);
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* if (sess == NULL) {
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* return -1;
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* }
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*
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* qcrypto_tls_session_set_callbacks(sess,
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* mysock_send,
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* mysock_recv
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* GINT_TO_POINTER(fd));
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*
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* while (1) {
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* int ret = qcrypto_tls_session_handshake(sess, errp);
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*
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* if (ret < 0) {
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* qcrypto_tls_session_free(sess);
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* return -1;
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* }
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*
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* switch(ret) {
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* case QCRYPTO_TLS_HANDSHAKE_COMPLETE:
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* if (qcrypto_tls_session_check_credentials(sess, errp) < )) {
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* qcrypto_tls_session_free(sess);
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* return -1;
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* }
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* goto done;
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* case QCRYPTO_TLS_HANDSHAKE_RECVING:
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* ...wait for GIO_IN event on fd...
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* break;
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* case QCRYPTO_TLS_HANDSHAKE_SENDING:
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* ...wait for GIO_OUT event on fd...
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* break;
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* }
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* }
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* done:
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*
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* ....send/recv payload data on sess...
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*
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* qcrypto_tls_session_free(sess):
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* }
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* </programlisting>
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* </example>
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*/
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typedef struct QCryptoTLSSession QCryptoTLSSession;
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#define QCRYPTO_TLS_SESSION_ERR_BLOCK -2
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/**
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* qcrypto_tls_session_new:
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* @creds: pointer to a TLS credentials object
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* @hostname: optional hostname to validate
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* @aclname: optional ACL to validate peer credentials against
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* @endpoint: role of the TLS session, client or server
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a new TLS session object that will be used to
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* negotiate a TLS session over an arbitrary data channel.
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* The session object can operate as either the server or
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* client, according to the value of the @endpoint argument.
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*
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* For clients, the @hostname parameter should hold the full
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* unmodified hostname as requested by the user. This will
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* be used to verify the against the hostname reported in
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* the server's credentials (aka x509 certificate).
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*
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* The @aclname parameter (optionally) specifies the name
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* of an access control list that will be used to validate
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* the peer's credentials. For x509 credentials, the ACL
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* will be matched against the CommonName shown in the peer's
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* certificate. If the session is acting as a server, setting
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* an ACL will require that the client provide a validate
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* x509 client certificate.
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*
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* After creating the session object, the I/O callbacks
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* must be set using the qcrypto_tls_session_set_callbacks()
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* method. A TLS handshake sequence must then be completed
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* using qcrypto_tls_session_handshake(), before payload
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* data is permitted to be sent/received.
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*
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* The session object must be released by calling
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* qcrypto_tls_session_free() when no longer required
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*
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* Returns: a TLS session object, or NULL on error.
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*/
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QCryptoTLSSession *qcrypto_tls_session_new(QCryptoTLSCreds *creds,
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const char *hostname,
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const char *aclname,
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QCryptoTLSCredsEndpoint endpoint,
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Error **errp);
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/**
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* qcrypto_tls_session_free:
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* @sess: the TLS session object
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*
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* Release all memory associated with the TLS session
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* object previously allocated by qcrypto_tls_session_new()
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*/
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void qcrypto_tls_session_free(QCryptoTLSSession *sess);
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G_DEFINE_AUTOPTR_CLEANUP_FUNC(QCryptoTLSSession, qcrypto_tls_session_free)
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/**
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* qcrypto_tls_session_require_thread_safety:
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* @sess: the TLS session object
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*
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* Mark that this TLS session will require thread safety
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* for concurrent I/O in both directions. This must be
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* called before the handshake is performed.
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*
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* This will activate a workaround for GNUTLS thread
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* safety issues, where appropriate for the negotiated
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* TLS session parameters.
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*/
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void qcrypto_tls_session_require_thread_safety(QCryptoTLSSession *sess);
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/**
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* qcrypto_tls_session_check_credentials:
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* @sess: the TLS session object
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* @errp: pointer to a NULL-initialized error object
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*
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* Validate the peer's credentials after a successful
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* TLS handshake. It is an error to call this before
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* qcrypto_tls_session_handshake() returns
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* QCRYPTO_TLS_HANDSHAKE_COMPLETE
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*
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* Returns 0 if the credentials validated, -1 on error
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*/
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int qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess,
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Error **errp);
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/*
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* These must return QCRYPTO_TLS_SESSION_ERR_BLOCK if the I/O
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* would block, but on other errors, must fill 'errp'
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*/
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typedef ssize_t (*QCryptoTLSSessionWriteFunc)(const char *buf,
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size_t len,
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void *opaque,
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Error **errp);
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typedef ssize_t (*QCryptoTLSSessionReadFunc)(char *buf,
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size_t len,
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void *opaque,
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Error **errp);
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/**
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* qcrypto_tls_session_set_callbacks:
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* @sess: the TLS session object
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* @writeFunc: callback for sending data
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* @readFunc: callback to receiving data
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* @opaque: data to pass to callbacks
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*
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* Sets the callback functions that are to be used for sending
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* and receiving data on the underlying data channel. Typically
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* the callbacks to write/read to/from a TCP socket, but there
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* is no assumption made about the type of channel used.
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*
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* The @writeFunc callback will be passed the encrypted
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* data to send to the remote peer.
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*
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* The @readFunc callback will be passed a pointer to fill
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* with encrypted data received from the remote peer
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*/
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void qcrypto_tls_session_set_callbacks(QCryptoTLSSession *sess,
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QCryptoTLSSessionWriteFunc writeFunc,
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QCryptoTLSSessionReadFunc readFunc,
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void *opaque);
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/**
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* qcrypto_tls_session_write:
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* @sess: the TLS session object
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* @buf: the plain text to send
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* @len: the length of @buf
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* @errp: pointer to hold returned error object
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*
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* Encrypt @len bytes of the data in @buf and send
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* it to the remote peer using the callback previously
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* registered with qcrypto_tls_session_set_callbacks()
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*
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* It is an error to call this before
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* qcrypto_tls_session_handshake() returns
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* QCRYPTO_TLS_HANDSHAKE_COMPLETE
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*
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* Returns: the number of bytes sent,
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* or QCRYPTO_TLS_SESSION_ERR_BLOCK if the write would block,
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* or -1 on error.
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*/
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ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess,
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const char *buf,
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size_t len,
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Error **errp);
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/**
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* qcrypto_tls_session_read:
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* @sess: the TLS session object
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* @buf: to fill with plain text received
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* @len: the length of @buf
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* @gracefulTermination: treat premature termination as graceful EOF
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* @errp: pointer to hold returned error object
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*
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* Receive up to @len bytes of data from the remote peer
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* using the callback previously registered with
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* qcrypto_tls_session_set_callbacks(), decrypt it and
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* store it in @buf.
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*
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* If @gracefulTermination is true, then a premature termination
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* of the TLS session will be treated as indicating EOF, as
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* opposed to an error.
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*
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* It is an error to call this before
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* qcrypto_tls_session_handshake() returns
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* QCRYPTO_TLS_HANDSHAKE_COMPLETE
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*
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* Returns: the number of bytes received,
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* or QCRYPTO_TLS_SESSION_ERR_BLOCK if the receive would block,
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* or -1 on error.
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*/
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ssize_t qcrypto_tls_session_read(QCryptoTLSSession *sess,
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char *buf,
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size_t len,
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bool gracefulTermination,
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Error **errp);
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/**
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* qcrypto_tls_session_check_pending:
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* @sess: the TLS session object
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*
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* Check if there are unread data in the TLS buffers that have
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* already been read from the underlying data source.
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*
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* Returns: the number of bytes available or zero
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*/
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size_t qcrypto_tls_session_check_pending(QCryptoTLSSession *sess);
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/**
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* qcrypto_tls_session_handshake:
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* @sess: the TLS session object
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* @errp: pointer to a NULL-initialized error object
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*
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* Start, or continue, a TLS handshake sequence. If
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* the underlying data channel is non-blocking, then
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* this method may return control before the handshake
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* is complete. On non-blocking channels the
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* return value determines whether the handshake
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* has completed, or is waiting to send or receive
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* data. In the latter cases, the caller should setup
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* an event loop watch and call this method again
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* once the underlying data channel is ready to read
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* or write again
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*/
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int qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
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Error **errp);
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typedef enum {
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QCRYPTO_TLS_HANDSHAKE_COMPLETE,
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QCRYPTO_TLS_HANDSHAKE_SENDING,
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QCRYPTO_TLS_HANDSHAKE_RECVING,
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} QCryptoTLSSessionHandshakeStatus;
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typedef enum {
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QCRYPTO_TLS_BYE_COMPLETE,
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QCRYPTO_TLS_BYE_SENDING,
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QCRYPTO_TLS_BYE_RECVING,
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} QCryptoTLSSessionByeStatus;
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/**
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* qcrypto_tls_session_bye:
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* @session: the TLS session object
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* @errp: pointer to a NULL-initialized error object
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*
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* Start, or continue, a TLS termination sequence. If the underlying
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* data channel is non-blocking, then this method may return control
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* before the termination is complete. The return value will indicate
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* whether the termination has completed, or is waiting to send or
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* receive data. In the latter cases, the caller should setup an event
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* loop watch and call this method again once the underlying data
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* channel is ready to read or write again.
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*/
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int
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qcrypto_tls_session_bye(QCryptoTLSSession *session, Error **errp);
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/**
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* qcrypto_tls_session_get_key_size:
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* @sess: the TLS session object
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* @errp: pointer to a NULL-initialized error object
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*
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* Check the size of the data channel encryption key
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*
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* Returns: the length in bytes of the encryption key
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* or -1 on error
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*/
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int qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
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Error **errp);
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/**
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* qcrypto_tls_session_get_peer_name:
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* @sess: the TLS session object
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*
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* Get the identified name of the remote peer. If the
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* TLS session was negotiated using x509 certificate
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* credentials, this will return the CommonName from
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* the peer's certificate. If no identified name is
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* available it will return NULL.
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*
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* The returned data must be released with g_free()
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* when no longer required.
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*
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* Returns: the peer's name or NULL.
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*/
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char *qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess);
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#endif /* QCRYPTO_TLSSESSION_H */
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