cifs: track the flavor of the NEGOTIATE reponse

Track what sort of NEGOTIATE response we get from the server, as that
will govern what sort of authentication types this socket will support.

There are three possibilities:

LANMAN: server sent legacy LANMAN-type response

UNENCAP: server sent a newer-style response, but extended security bit
wasn't set. This socket will only support unencapsulated auth types.

EXTENDED: server sent a newer-style response with the extended security
bit set. This is necessary to support krb5 and ntlmssp auth types.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifssmb.c

@@ -615,6 +615,7 @@ CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
 		rc = -EOPNOTSUPP;
 		goto neg_err_exit;
 	} else if (pSMBr->hdr.WordCount == 13) {
+		server->negflavor = CIFS_NEGFLAVOR_LANMAN;
 		rc = decode_lanman_negprot_rsp(server, pSMBr, secFlags);
 		goto signing_check;
 	} else if (pSMBr->hdr.WordCount != 17) {
@@ -666,17 +667,21 @@ CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
 	server->timeAdj = (int)(__s16)le16_to_cpu(pSMBr->ServerTimeZone);
 	server->timeAdj *= 60;
 
-	if (pSMBr->EncryptionKeyLength == CIFS_CRYPTO_KEY_SIZE)
+	if (pSMBr->EncryptionKeyLength == CIFS_CRYPTO_KEY_SIZE) {
+		server->negflavor = CIFS_NEGFLAVOR_UNENCAP;
 		memcpy(ses->server->cryptkey, pSMBr->u.EncryptionKey,
 		       CIFS_CRYPTO_KEY_SIZE);
-	else if ((pSMBr->hdr.Flags2 & SMBFLG2_EXT_SEC ||
+	} else if ((pSMBr->hdr.Flags2 & SMBFLG2_EXT_SEC ||
 			server->capabilities & CAP_EXTENDED_SECURITY) &&
-				(pSMBr->EncryptionKeyLength == 0))
+				(pSMBr->EncryptionKeyLength == 0)) {
+		server->negflavor = CIFS_NEGFLAVOR_EXTENDED;
 		rc = decode_ext_sec_blob(server, pSMBr);
-	else if (server->sec_mode & SECMODE_PW_ENCRYPT)
+	} else if (server->sec_mode & SECMODE_PW_ENCRYPT) {
 		rc = -EIO; /* no crypt key only if plain text pwd */
-	else
+	} else {
+		server->negflavor = CIFS_NEGFLAVOR_UNENCAP;
 		server->capabilities &= ~CAP_EXTENDED_SECURITY;
+	}
 
 signing_check:
 	if (!rc)