From 926674de6705f0f1dbf29a62fd758d0977f535d6 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Sun, 28 Oct 2018 13:13:23 -0500
Subject: [PATCH] smb3: on kerberos mount if server doesn't specify auth type
 use krb5
Git-commit: 926674de6705f0f1dbf29a62fd758d0977f535d6
Patch-mainline: v4.20-rc1
References: bsc#1051510, bsc#1144333

Some servers (e.g. Azure) do not include a spnego blob in the SMB3
negotiate protocol response, so on kerberos mounts ("sec=krb5")
we can fail, as we expected the server to list its supported
auth types (OIDs in the spnego blob in the negprot response).
Change this so that on krb5 mounts we default to trying krb5 if the
server doesn't list its supported protocol mechanisms.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
CC: Stable <stable@vger.kernel.org>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/cifs_spnego.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index b611fc2e8984..7f01c6e60791 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -147,8 +147,10 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo)
 		sprintf(dp, ";sec=krb5");
 	else if (server->sec_mskerberos)
 		sprintf(dp, ";sec=mskrb5");
-	else
-		goto out;
+	else {
+		cifs_dbg(VFS, "unknown or missing server auth type, use krb5\n");
+		sprintf(dp, ";sec=krb5");
+	}
 
 	dp = description + strlen(description);
 	sprintf(dp, ";uid=0x%x",
-- 
2.16.4