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a2458b6f69
GNUTLS takes a paranoid approach when seeing 0 bytes returned by the underlying OS read() function. It will consider this an error and return GNUTLS_E_PREMATURE_TERMINATION instead of propagating the 0 return value. It expects apps to arrange for clean termination at the protocol level and not rely on seeing EOF from a read call to detect shutdown. This is to harden apps against a malicious 3rd party causing termination of the sockets layer. This is unhelpful for the QEMU NBD code which does have a clean protocol level shutdown, but still relies on seeing 0 from the I/O channel read in the coroutine handling incoming replies. The upshot is that when using a plain NBD connection shutdown is silent, but when using TLS, the client spams the console with Cannot read from TLS channel: Broken pipe The NBD connection has, however, called qio_channel_shutdown() at this point to indicate that it is done with I/O. This gives the opportunity to optimize the code such that when the channel has been shutdown in the read direction, the error code GNUTLS_E_PREMATURE_TERMINATION gets turned into a '0' return instead of an error. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20181119134228.11031-1-berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
147 lines
4.8 KiB
C
147 lines
4.8 KiB
C
/*
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* QEMU I/O channels TLS driver
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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 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 QIO_CHANNEL_TLS_H
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#define QIO_CHANNEL_TLS_H
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#include "io/channel.h"
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#include "io/task.h"
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#include "crypto/tlssession.h"
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#define TYPE_QIO_CHANNEL_TLS "qio-channel-tls"
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#define QIO_CHANNEL_TLS(obj) \
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OBJECT_CHECK(QIOChannelTLS, (obj), TYPE_QIO_CHANNEL_TLS)
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typedef struct QIOChannelTLS QIOChannelTLS;
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/**
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* QIOChannelTLS
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*
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* The QIOChannelTLS class provides a channel wrapper which
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* can transparently run the TLS encryption protocol. It is
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* usually used over a TCP socket, but there is actually no
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* technical restriction on which type of master channel is
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* used as the transport.
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*
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* This channel object is capable of running as either a
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* TLS server or TLS client.
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*/
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struct QIOChannelTLS {
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QIOChannel parent;
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QIOChannel *master;
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QCryptoTLSSession *session;
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QIOChannelShutdown shutdown;
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};
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/**
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* qio_channel_tls_new_server:
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* @master: the underlying channel object
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* @creds: the credentials to use for TLS handshake
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* @aclname: the access control list for validating clients
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a new TLS channel that runs the server side of
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* a TLS session. The TLS session handshake will use the
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* credentials provided in @creds. If the @aclname parameter
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* is non-NULL, then the client will have to provide
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* credentials (ie a x509 client certificate) which will
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* then be validated against the ACL.
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*
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* After creating the channel, it is mandatory to call
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* the qio_channel_tls_handshake() method before attempting
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* todo any I/O on the channel.
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*
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* Once the handshake has completed, all I/O should be done
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* via the new TLS channel object and not the original
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* master channel
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*
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* Returns: the new TLS channel object, or NULL
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*/
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QIOChannelTLS *
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qio_channel_tls_new_server(QIOChannel *master,
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QCryptoTLSCreds *creds,
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const char *aclname,
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Error **errp);
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/**
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* qio_channel_tls_new_client:
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* @master: the underlying channel object
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* @creds: the credentials to use for TLS handshake
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* @hostname: the user specified server hostname
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a new TLS channel that runs the client side of
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* a TLS session. The TLS session handshake will use the
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* credentials provided in @creds. The @hostname parameter
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* should provide the user specified hostname of the server
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* and will be validated against the server's credentials
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* (ie CommonName of the x509 certificate)
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*
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* After creating the channel, it is mandatory to call
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* the qio_channel_tls_handshake() method before attempting
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* todo any I/O on the channel.
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*
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* Once the handshake has completed, all I/O should be done
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* via the new TLS channel object and not the original
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* master channel
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*
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* Returns: the new TLS channel object, or NULL
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*/
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QIOChannelTLS *
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qio_channel_tls_new_client(QIOChannel *master,
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QCryptoTLSCreds *creds,
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const char *hostname,
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Error **errp);
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/**
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* qio_channel_tls_handshake:
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* @ioc: the TLS channel object
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* @func: the callback to invoke when completed
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* @opaque: opaque data to pass to @func
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* @destroy: optional callback to free @opaque
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* @context: the context that TLS handshake will run with. If %NULL,
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* the default context will be used
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*
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* Perform the TLS session handshake. This method
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* will return immediately and the handshake will
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* continue in the background, provided the main
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* loop is running. When the handshake is complete,
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* or fails, the @func callback will be invoked.
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*/
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void qio_channel_tls_handshake(QIOChannelTLS *ioc,
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QIOTaskFunc func,
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gpointer opaque,
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GDestroyNotify destroy,
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GMainContext *context);
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/**
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* qio_channel_tls_get_session:
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* @ioc: the TLS channel object
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*
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* Get the TLS session used by the channel.
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*
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* Returns: the TLS session
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*/
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QCryptoTLSSession *
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qio_channel_tls_get_session(QIOChannelTLS *ioc);
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#endif /* QIO_CHANNEL_TLS_H */
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