s3:smbd multichannel: always refresh the network information

To maintain SMB Multichannel, windows client might periodically query with
FSCTL_QUERY_NETWORK_INTERFACE_INFO to get SMB server's network information,
in my case windows server 2022 would do this every 10 minutes (600 seconds).

Consider a scenario: the network information might have changed between
these queries, some become link down, new interface is link up, network
speed is changed, and etc. So far smbd might not aware of these changes and
still report out-of-date network information to windows client, until we
manually send a SIGHUP to smbd in order to trigger load_interfaces():
smbd_sig_hup_handler() > reload_services () > load_interfaces()
This might be a bit inconvenient because it is hard to decide when should
we manually send a SIGHUP to smbd for refreshing network information.

This patch adds load_interfaces() at fsctl_network_iface_info(), while smbd
received FSCTL_QUERY_NETWORK_INTERFACE_INFO would go through this and refresh
local_interfaces, then respond to client with up-to-date network information;
also refresh num_ifaces to make sure interfaces count is consistent.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15547

Signed-off-by: Jones Syue <jonessyue@qnap.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Björn Jacke <bjacke@samba.org>
(cherry picked from commit 318fd95d5ea63724798592eb6b4eebaecfa0cbfb)

Autobuild-User(v4-18-test): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(v4-18-test): Fri Jan  5 13:46:39 UTC 2024 on atb-devel-224

diff --git a/source3/smbd/smb2_ioctl_network_fs.c b/source3/smbd/smb2_ioctl_network_fs.c
index 5b396855ca620086c25580aa94ed05eb8adfa221..9ef99dca90f318a45e343467ccd4954999bc7e97 100644 (file)
--- a/source3/smbd/smb2_ioctl_network_fs.c
+++ b/source3/smbd/smb2_ioctl_network_fs.c
@@ -366,7 +366,7 @@ static NTSTATUS fsctl_network_iface_info(TALLOC_CTX *mem_ctx,
        struct fsctl_net_iface_info *first = NULL;
        struct fsctl_net_iface_info *last = NULL;
        size_t i;
-       size_t num_ifaces = iface_count();
+       size_t num_ifaces;
        enum ndr_err_code ndr_err;
        struct cluster_movable_ips *cluster_movable_ips = NULL;
        int ret;
@@ -375,6 +375,16 @@ static NTSTATUS fsctl_network_iface_info(TALLOC_CTX *mem_ctx,
                return NT_STATUS_INVALID_PARAMETER;
        }
 
+       /*
+        * The list of probed interfaces might have changed, we might need to
+        * refresh local_interfaces to get up-to-date network information, and
+        * respond to clients which sent FSCTL_QUERY_NETWORK_INTERFACE_INFO.
+        * For example, network speed is changed, interfaces count is changed
+        * (some link down or link up), and etc.
+        */
+       load_interfaces();
+       num_ifaces = iface_count();
+
        *out_output = data_blob_null;
 
        array = talloc_zero_array(mem_ctx,