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

BugLink: https://bugs.launchpad.net/bugs/1792580
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>
(cherry picked from commit 395a2076b4064f97d3fce03af15210ff2a7bb7f9)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index e3026e211990c240f9a8dd375acb62270ce29967..3d9ef026736262864a532093fde9217fa9d8b928 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2415,7 +2415,7 @@ 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();