cifs: set MAY_SIGN when sec=krb5

commit 0b7bc840 upstream.

Setting this secFlg allows usage of dfs where some servers require
signing and others don't.
Signed-off-by: Martijn de Gouw <martijn.de.gouw@prodrive.nl>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
[Joseph Salisbury: This backport was done so including mainline commit
8830d7e0 is not needed.]
BugLink: http://bugs.launchpad.net/bugs/1285723Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/cifs/connect.c

@@ -1113,7 +1113,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 				cERROR(1, "Krb5 cifs privacy not supported");
 				goto cifs_parse_mount_err;
 			} else if (strnicmp(value, "krb5", 4) == 0) {
-				vol->secFlg |= CIFSSEC_MAY_KRB5;
+				vol->secFlg |= CIFSSEC_MAY_KRB5 | 
+					CIFSSEC_MAY_SIGN;
 			} else if (strnicmp(value, "ntlmsspi", 8) == 0) {
 				vol->secFlg |= CIFSSEC_MAY_NTLMSSP |
 					CIFSSEC_MUST_SIGN;