From d706e465682307df95a723e1a74b32c0db93e259 Mon Sep 17 00:00:00 2001
From: John Snow <jsnow@redhat.com>
Date: Fri, 22 Mar 2019 03:22:30 +0100
Subject: [PATCH 063/163] nbd/server: Ignore write errors when replying to
 NBD_OPT_ABORT
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RH-Author: John Snow <jsnow@redhat.com>
Message-id: <20190322032241.8111-18-jsnow@redhat.com>
Patchwork-id: 85105
O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 17/28] nbd/server: Ignore write errors when replying to NBD_OPT_ABORT
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: Eric Blake <eblake@redhat.com>

Commit 37ec36f6 intentionally ignores errors when trying to reply
to an NBD_OPT_ABORT request for plaintext clients, but did not make
the same change for a TLS server.  Since NBD_OPT_ABORT is
documented as being a potential for an EPIPE when the client hangs
up without waiting for our reply, we don't need to pollute the
server's output with that failure.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20181117223221.2198751-1-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit 3e99ebb9d3df15ce0ecf1b435816c9c46ee9a1ad)
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 nbd/server.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/nbd/server.c b/nbd/server.c
index 418b1d4..e8fd6b4 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1134,12 +1134,16 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
                 return -EINVAL;
 
             default:
-                ret = nbd_opt_drop(client, NBD_REP_ERR_TLS_REQD, errp,
+                /* Let the client keep trying, unless they asked to
+                 * quit. Always try to give an error back to the
+                 * client; but when replying to OPT_ABORT, be aware
+                 * that the client may hang up before receiving the
+                 * error, in which case we are fine ignoring the
+                 * resulting EPIPE. */
+                ret = nbd_opt_drop(client, NBD_REP_ERR_TLS_REQD,
+                                   option == NBD_OPT_ABORT ? NULL : errp,
                                    "Option 0x%" PRIx32
                                    " not permitted before TLS", option);
-                /* Let the client keep trying, unless they asked to
-                 * quit. In this mode, we've already sent an error, so
-                 * we can't ack the abort.  */
                 if (option == NBD_OPT_ABORT) {
                     return 1;
                 }
-- 
1.8.3.1