diff options
| author | Daniel P. Berrangé <berrange@redhat.com> | 2018-11-19 13:42:28 +0000 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2018-11-19 11:16:46 -0600 |
| commit | a2458b6f6998c9a079f710ed7495d5c6f037e942 (patch) | |
| tree | 327f84a768219485e03dbdafa57c4315cf2272fc /include/io | |
| parent | 3e99ebb9d3df15ce0ecf1b435816c9c46ee9a1ad (diff) | |
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 'include/io')
| -rw-r--r-- | include/io/channel-tls.h | 1 | ||||
| -rw-r--r-- | include/io/channel.h | 6 |
2 files changed, 4 insertions, 3 deletions
diff --git a/include/io/channel-tls.h b/include/io/channel-tls.h index 87fcaf9146..fdbdf12feb 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 e8cdadb0b0..da2f138200 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, |