[PATCH v2 2/2] migration/multifd: Ensure we're not given a socket for file migration

[Fabiano Rosas]

When doing migration using the fd: URI, the incoming migration starts
before the user has passed the file descriptor to QEMU. This means
that the checks at migration_channels_and_transport_compatible()
happen too soon and we need to allow a migration channel of type
SOCKET_ADDRESS_TYPE_FD even though socket migration is not supported
with multifd.

The commit decdc76772 ("migration/multifd: Add mapped-ram support to
fd: URI") was supposed to add a second check prior to starting
migration to make sure a socket fd is not passed instead of a file fd,
but failed to do so.

Add the missing verification.

Fixes: decdc76772 ("migration/multifd: Add mapped-ram support to fd: URI")
Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
 migration/fd.c   | 8 ++++++++
 migration/file.c | 7 +++++++
 2 files changed, 15 insertions(+)

diff --git a/migration/fd.c b/migration/fd.c
index 39a52e5c90..c07030f715 100644
--- a/migration/fd.c
+++ b/migration/fd.c
@@ -22,6 +22,7 @@
 #include "migration.h"
 #include "monitor/monitor.h"
 #include "io/channel-file.h"
+#include "io/channel-socket.h"
 #include "io/channel-util.h"
 #include "options.h"
 #include "trace.h"
@@ -95,6 +96,13 @@ void fd_start_incoming_migration(const char *fdname, Error 
**errp)
     }
 
     if (migrate_multifd()) {
+        if (fd_is_socket(fd)) {
+            error_setg(errp,
+                       "Multifd migration to a socket FD is not supported");
+            object_unref(ioc);
+            return;
+        }
+
         file_create_incoming_channels(ioc, errp);
     } else {
         qio_channel_set_name(ioc, "migration-fd-incoming");
diff --git a/migration/file.c b/migration/file.c
index ddde0ca818..b6e8ba13f2 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -15,6 +15,7 @@
 #include "file.h"
 #include "migration.h"
 #include "io/channel-file.h"
+#include "io/channel-socket.h"
 #include "io/channel-util.h"
 #include "options.h"
 #include "trace.h"
@@ -58,6 +59,12 @@ bool file_send_channel_create(gpointer opaque, Error **errp)
     int fd = fd_args_get_fd();
 
     if (fd && fd != -1) {
+        if (fd_is_socket(fd)) {
+            error_setg(errp,
+                       "Multifd migration to a socket FD is not supported");
+            goto out;
+        }
+
         ioc = qio_channel_file_new_dupfd(fd, errp);
     } else {
         ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
-- 
2.35.3