From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB883C4338F for ; Wed, 18 Aug 2021 16:29:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD05360EFE for ; Wed, 18 Aug 2021 16:29:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232697AbhHRQaE (ORCPT ); Wed, 18 Aug 2021 12:30:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229471AbhHRQaB (ORCPT ); Wed, 18 Aug 2021 12:30:01 -0400 Received: from mail-ej1-x62b.google.com (mail-ej1-x62b.google.com [IPv6:2a00:1450:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6EE7DC06179A for ; Wed, 18 Aug 2021 09:29:26 -0700 (PDT) Received: by mail-ej1-x62b.google.com with SMTP id d11so6201753eja.8 for ; Wed, 18 Aug 2021 09:29:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Lx2mQZ//Ii6+5mpE/8cN+N2w2n4hvMHo49+Kx6QlYoc=; b=EfHMTAV3oXYc/2BYTKgl/fTgK/tvHEVzrvRu3pWThHwyOd07j5VsCeORdLbwf1wI25 39+oMF0w+FCS1aR5zSZ3KIs/YMJ3g3peu3+pTFueOkkXjtM+7pwNIF9Bf1c0HEu6fKwc RYU7+Tn2xLUBhKEm2tGi0UX5SOAmQi39/diEOODj52iOOeLn19NpiRLqz+DIvBHQIEOx 4PwjkbYxOlEWWaHCbMbKL8mcNRG3fyheJIgMkchjc6Jdn1RqKfUe6X1rVpsEKLk0E24q GXzF5BaskLE0ieiXQVYKbMs6U4PCJFGNGHa/WpqrzDXQKzCGm84E5G9ytZZ/JWGoPTD7 Ah6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Lx2mQZ//Ii6+5mpE/8cN+N2w2n4hvMHo49+Kx6QlYoc=; b=nFftIYJGdwYXrQRNo3Cetp/hkmBHHg45uzAkwcyDwfaBEYkcOwngKh4o7oJSP8ZaWl rspQJVmvbHlMladLCGP7345lTopVRRDxVPYpL8Ta4/qT1aiX8+RAzHLj5om8DJnf56+1 9GbvDxKfV6UWE5oGZOCnQEGQWs79bZL19rPR89oCeXoEbRvLEkBoahFdw1PWXre5U6PY pAFWMvUz2ps3YbzduReNjRtMhGcAsGfe5xfq5yNBZSb/QKnoSpYd5fKJisZ1WBVyW3oC /YYBT6lQS8bkkhEWN7aA5ZovMiFEkD8uedqWLYe3t7du8PQ/iJhiQY2k5YTKjb24WXDR VLsA== X-Gm-Message-State: AOAM5304rmRo4HSnppGvCSAH8ftceS227tWFJSDXBwVrIpk2d081SS0m 9ctCFMyk8UEdBgwTT9J5tmM4+lStGGUmtTtOoRI= X-Google-Smtp-Source: ABdhPJxQpJF8sX3ssccRZmf6IQoOIB3MaOXGCdTDTasT/wKKPrjxy3AjkpEMMbD7apk1W0oqYqxNmEdAvRk6pNnliUU= X-Received: by 2002:a17:906:3782:: with SMTP id n2mr10301504ejc.368.1629304165056; Wed, 18 Aug 2021 09:29:25 -0700 (PDT) MIME-Version: 1.0 References: <20210818041021.1210797-1-lsahlber@redhat.com> <815daf08-7569-59ce-0318-dfe2b16e1d96@talpey.com> In-Reply-To: <815daf08-7569-59ce-0318-dfe2b16e1d96@talpey.com> From: ronnie sahlberg Date: Thu, 19 Aug 2021 02:29:13 +1000 Message-ID: Subject: Re: Disable key exchange if ARC4 is not available To: Tom Talpey Cc: Ronnie Sahlberg , linux-cifs , Steve French Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org On Wed, Aug 18, 2021 at 11:18 PM Tom Talpey wrote: > > On 8/18/2021 12:10 AM, Ronnie Sahlberg wrote: > > Steve, > > > > We depend on ARC4 for generating the encrypted session key in key exchange. > > This patch disables the key exchange/encrypted session key for ntlmssp > > IF the kernel does not have any ARC4 support. > > > > This allows to build the cifs module even if ARC4 has been removed > > though with a weaker type of NTLMSSP support. > > It's a good goal but it seems wrong to downgrade the security > so silently. Wouldn't it be a better approach to select ARC4, > and thereby force the build to succeed or fail? Alternatively, > change the #ifndef ARC4 to a positive option named (for example) > DOWNGRADED_NTLMSSP or something equally foreboding? Good point. Maybe we should drop this patch and instead copy ARC4 into fs/cifs so we have a private version of the code in cifs.ko. And do the same for md4 and md5. > > Tom.