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author | Daniel P. Berrangé <berrange@redhat.com> | 2018-11-19 13:42:28 +0000 |
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committer | Eric Blake <eblake@redhat.com> | 2018-11-19 11:16:46 -0600 |
commit | a2458b6f6998c9a079f710ed7495d5c6f037e942 (patch) | |
tree | 327f84a768219485e03dbdafa57c4315cf2272fc /io/channel-tls.c | |
parent | 3e99ebb9d3df15ce0ecf1b435816c9c46ee9a1ad (diff) | |
download | qemu-a2458b6f6998c9a079f710ed7495d5c6f037e942.zip qemu-a2458b6f6998c9a079f710ed7495d5c6f037e942.tar.gz qemu-a2458b6f6998c9a079f710ed7495d5c6f037e942.tar.bz2 |
io: return 0 for EOF in TLS session read after shutdown
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>
Diffstat (limited to 'io/channel-tls.c')
-rw-r--r-- | io/channel-tls.c | 5 |
1 files changed, 5 insertions, 0 deletions
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); } |