cifs: connect to servername instead of IP for IPC$ share

This patch is required allows access to a Microsoft fileserver failover
cluster behind a 1:1 NAT firewall.

The change also provides stronger context for authentication and share
connection (see MS-SMB2 3.3.5.7 and MS-SRVS 3.1.6.8) as noted by
Tom Talpey, and addresses comments about the buffer size for the UNC
made by Aurélien Aptel.

Signed-off-by: Thomas Werschlein <thomas.werschlein@geo.uzh.ch>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Tom Talpey <ttalpey@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
CC: Stable <stable@vger.kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c832a8a1970a..7aa08dba4719 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2547,7 +2547,7 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb_vol *volume_info)
         if (tcon == NULL)
                 return -ENOMEM;
 
-        snprintf(unc, sizeof(unc), "\\\\%s\\IPC$", ses->serverName);
+        snprintf(unc, sizeof(unc), "\\\\%s\\IPC$", ses->server->hostname);
 
         /* cannot fail */
         nls_codepage = load_nls_default();