[PATCH 5.0 045/246] cifs: Accept validate negotiate if server return NT_STATUS_NOT_SUPPORTED

[Greg Kroah-Hartman]

5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 969ae8e8d4ee54c99134d3895f2adf96047f5bee ]

Old windows version or Netapp SMB server will return
NT_STATUS_NOT_SUPPORTED since they do not allow or implement
FSCTL_VALIDATE_NEGOTIATE_INFO. The client should accept the response
provided it's properly signed.

See
https://blogs.msdn.microsoft.com/openspecification/2012/06/28/smb3-secure-dialect-negotiation/

and

MS-SMB2 validate negotiate response processing:
https://msdn.microsoft.com/en-us/library/hh880630.aspx

Samba client had already handled it.
https://bugzilla.samba.org/attachment.cgi?id=13285&action=edit

Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/cifs/smb2pdu.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 104905732fbe..53642a237bf9 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -986,8 +986,14 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
 	rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,
 		FSCTL_VALIDATE_NEGOTIATE_INFO, true /* is_fsctl */,
 		(char *)pneg_inbuf, inbuflen, (char **)&pneg_rsp, &rsplen);
-
-	if (rc != 0) {
+	if (rc == -EOPNOTSUPP) {
+		/*
+		 * Old Windows versions or Netapp SMB server can return
+		 * not supported error. Client should accept it.
+		 */
+		cifs_dbg(VFS, "Server does not support validate negotiate\n");
+		return 0;
+	} else if (rc != 0) {
 		cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", rc);
 		rc = -EIO;
 		goto out_free_inbuf;
-- 
2.19.1