From d3244c405b0968db4629855567c3a2c7729bea36 Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Fri, 22 Mar 2019 03:22:31 +0100

Subject: [PATCH 064/163] io: return 0 for EOF in TLS session read after

 shutdown

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20190322032241.8111-19-jsnow@redhat.com>

Patchwork-id: 85099

O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 18/28] io: return 0 for EOF in TLS session read after shutdown

Bugzilla: 1691563

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Daniel P. Berrangé <berrange@redhat.com>

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>

(cherry picked from commit a2458b6f6998c9a079f710ed7495d5c6f037e942)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 crypto/tlssession.c      | 3 +++

 include/io/channel-tls.h | 1 +

 include/io/channel.h     | 6 +++---

 io/channel-tls.c         | 5 +++++

 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/crypto/tlssession.c b/crypto/tlssession.c

index 96a02de..68e0114 100644

--- a/crypto/tlssession.c

+++ b/crypto/tlssession.c

@@ -427,6 +427,9 @@ qcrypto_tls_session_read(QCryptoTLSSession *session,

         case GNUTLS_E_INTERRUPTED:

             errno = EINTR;

             break;

+        case GNUTLS_E_PREMATURE_TERMINATION:

+            errno = ECONNABORTED;

+            break;

         default:

             errno = EIO;

             break;

diff --git a/include/io/channel-tls.h b/include/io/channel-tls.h

index 87fcaf9..fdbdf12 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 e8cdadb..da2f138 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 = 1,

+    QIO_CHANNEL_SHUTDOWN_WRITE = 2,

+    QIO_CHANNEL_SHUTDOWN_BOTH = 3,

 };

 typedef gboolean (*QIOChannelFunc)(QIOChannel *ioc,

diff --git a/io/channel-tls.c b/io/channel-tls.c

index 9628e6f..c98ead2 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 == 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 = QIO_CHANNEL_TLS(ioc);

+    tioc->shutdown |= how;

+

     return qio_channel_shutdown(tioc->master, how, errp);

 }

-- 

1.8.3.1