From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51333) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gOnkx-0008Vv-Vv for qemu-devel@nongnu.org; Mon, 19 Nov 2018 12:54:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gOnkw-0002Vd-Cn for qemu-devel@nongnu.org; Mon, 19 Nov 2018 12:54:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41254) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gOnkw-0002U8-2A for qemu-devel@nongnu.org; Mon, 19 Nov 2018 12:54:42 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 690253082E52 for ; Mon, 19 Nov 2018 17:54:41 +0000 (UTC) From: Eric Blake Date: Mon, 19 Nov 2018 11:54:21 -0600 Message-Id: <20181119175427.2298497-7-eblake@redhat.com> In-Reply-To: <20181119175427.2298497-1-eblake@redhat.com> References: <20181119175427.2298497-1-eblake@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL 06/12] io: return 0 for EOF in TLS session read after shutdown List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org From: Daniel P. Berrang=C3=A9 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. Berrang=C3=A9 Message-Id: <20181119134228.11031-1-berrange@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Eric Blake --- include/io/channel-tls.h | 1 + include/io/channel.h | 6 +++--- crypto/tlssession.c | 3 +++ io/channel-tls.c | 5 +++++ 4 files changed, 12 insertions(+), 3 deletions(-) diff --git a/include/io/channel-tls.h b/include/io/channel-tls.h index 87fcaf91463..fdbdf12feb1 100644 --- a/include/io/channel-tls.h +++ b/include/io/channel-tls.h @@ -48,6 +48,7 @@ struct QIOChannelTLS { QIOChannel parent; QIOChannel *master; QCryptoTLSSession *session; + QIOChannelShutdown shutdown; }; /** diff --git a/include/io/channel.h b/include/io/channel.h index e8cdadb0b07..da2f1382002 100644 --- a/include/io/channel.h +++ b/include/io/channel.h @@ -51,9 +51,9 @@ enum QIOChannelFeature { typedef enum QIOChannelShutdown QIOChannelShutdown; enum QIOChannelShutdown { - QIO_CHANNEL_SHUTDOWN_BOTH, - QIO_CHANNEL_SHUTDOWN_READ, - QIO_CHANNEL_SHUTDOWN_WRITE, + QIO_CHANNEL_SHUTDOWN_READ =3D 1, + QIO_CHANNEL_SHUTDOWN_WRITE =3D 2, + QIO_CHANNEL_SHUTDOWN_BOTH =3D 3, }; typedef gboolean (*QIOChannelFunc)(QIOChannel *ioc, diff --git a/crypto/tlssession.c b/crypto/tlssession.c index 2f28fa7f71b..0dedd4af526 100644 --- a/crypto/tlssession.c +++ b/crypto/tlssession.c @@ -473,6 +473,9 @@ qcrypto_tls_session_read(QCryptoTLSSession *session, case GNUTLS_E_INTERRUPTED: errno =3D EINTR; break; + case GNUTLS_E_PREMATURE_TERMINATION: + errno =3D ECONNABORTED; + break; default: errno =3D EIO; break; diff --git a/io/channel-tls.c b/io/channel-tls.c index 9628e6fa479..c98ead21b01 100644 --- a/io/channel-tls.c +++ b/io/channel-tls.c @@ -275,6 +275,9 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc, } else { return QIO_CHANNEL_ERR_BLOCK; } + } else if (errno =3D=3D ECONNABORTED && + (tioc->shutdown & QIO_CHANNEL_SHUTDOWN_READ)) { + return 0; } error_setg_errno(errp, errno, @@ -357,6 +360,8 @@ static int qio_channel_tls_shutdown(QIOChannel *ioc, { QIOChannelTLS *tioc =3D QIO_CHANNEL_TLS(ioc); + tioc->shutdown |=3D how; + return qio_channel_shutdown(tioc->master, how, errp); } --=20 2.17.2