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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88910C3525B for ; Wed, 6 Apr 2022 09:03:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383832AbiDFJDz (ORCPT ); Wed, 6 Apr 2022 05:03:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1444335AbiDFIzz (ORCPT ); Wed, 6 Apr 2022 04:55:55 -0400 Received: from mail-qt1-x833.google.com (mail-qt1-x833.google.com [IPv6:2607:f8b0:4864:20::833]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B05CBD7EC for ; Tue, 5 Apr 2022 18:19:12 -0700 (PDT) Received: by mail-qt1-x833.google.com with SMTP id b18so2003176qtk.13 for ; Tue, 05 Apr 2022 18:19:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:from:to:cc:subject:references:mime-version :content-disposition:in-reply-to; bh=emQSRtRyiIFOLZBRRD9ok+SvUgg5HT0mxHFWqehp0vo=; b=liEzV1DvukrzML5boo3DbzOsgqEOmW0TeGZTRGeDBUiO58NX4hoZ95SKtZ0x5lxoy/ D+UyQgPzqMzwbGKoyaljyyvCPgry06NMaGJrvORwjJXzRsgikKeJ59XIt4sCqr0WH0PZ foni+TAvduk8iqwj62A/m+7RyRpjJBxUB0ZQuBILLV3XWPtEe0uOWPBOQpClr8ZbCf5y zVh7ul4pC0MnQA170gM0tkNixTeWAKfJGqKxvJxx70YiTFBWKtvIabgOhUdKlW7P5lPu veOX0IOPELZ3Oq1VYBpIdI3ZRGMHlbBCRZutv8u83QPzUSNJFnymCzyO7+6+Vq8+zHSE TpRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:from:to:cc:subject:references :mime-version:content-disposition:in-reply-to; bh=emQSRtRyiIFOLZBRRD9ok+SvUgg5HT0mxHFWqehp0vo=; b=8PFNyWFedcvGSHVTdsxgLZqOLwtc6cc4d539Um443TxPeIrDQcv8MaAJl1na9+6qZ9 LsenNuMYoArXYUjfZSFCxR7dzZG+5cYG0OzRzp53gcCd4vv/0S/vnJ06rLo6Kltt0Ehu o+/TyldIsvAFEl7USxO0QPrzn7ClAK84CjRwGOEa2n+a2snK31Ru/T11ywHhwkXInxV7 3Gdgp+s/wgghUqAVyuKp3/M6jVqvx5/Q78M9FwUfruv6NM3DzjTsnQD1TrGdrRABnf6h sb1Yk/ncHqFy/Itx+jtzzZ/5/P92S+Te9v4SP3itDMPkz0aoN2FERQ2CXJL/fbtc628y OAgg== X-Gm-Message-State: AOAM532BAlqwa1fZiG6Azv9rCAeRyzxl166jIZ5Ue2TZC6dz7yNOlloN PinU0hBytGWRa5wgin39M5hVCadwCc8= X-Google-Smtp-Source: ABdhPJw3H1ruWxhuQ05X1p8z8JYG/k0+IbQoPX9aYytL4Pwxr7a6RJLhDMF3ORYFkO683VqFRlZ0KQ== X-Received: by 2002:a05:620a:2886:b0:699:bab7:ae78 with SMTP id j6-20020a05620a288600b00699bab7ae78mr4108850qkp.618.1649207951145; Tue, 05 Apr 2022 18:19:11 -0700 (PDT) Received: from localhost ([193.203.214.57]) by smtp.gmail.com with ESMTPSA id x18-20020a05622a001200b002eb856d7786sm12382288qtw.84.2022.04.05.18.19.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Apr 2022 18:19:10 -0700 (PDT) Message-ID: <624cea8e.1c69fb81.422be.e03b@mx.google.com> X-Google-Original-Message-ID: <20220406011907.GA2458824@cgel.zte@gmail.com> Date: Wed, 6 Apr 2022 01:19:07 +0000 From: CGEL To: Richard Guy Briggs Cc: Paul Moore , kbuild-all@lists.01.org, Zeal Robot , linux-kernel@vger.kernel.org, eparis@redhat.com, dai.shixin@zte.com.cn, Yang Yang , linux-audit@redhat.com, ink@jurassic.park.msu.ru, huang.junhua@zte.com.cn, guo.xiaofeng@zte.com.cn, mattst88@gmail.com Subject: Re: [PATCH] audit: do a quick exit when syscall number is invalid References: <20220326094654.2361956-1-yang.yang29@zte.com.cn> <62465bf3.1c69fb81.d5424.365e@mx.google.com> <2777189.mvXUDI8C0e@x2> <624803f7.1c69fb81.972da.2dd0@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 04, 2022 at 11:58:50AM -0400, Richard Guy Briggs wrote: > On 2022-04-02 08:06, CGEL wrote: > > On Fri, Apr 01, 2022 at 10:16:45AM -0400, Paul Moore wrote: > > > On Fri, Apr 1, 2022 at 9:39 AM Steve Grubb wrote: > > > > On Thursday, March 31, 2022 9:57:05 PM EDT CGEL wrote: > > > > > On Thu, Mar 31, 2022 at 10:16:23AM -0400, Paul Moore wrote: > > > > > > On Wed, Mar 30, 2022 at 10:29 PM CGEL wrote: > > > > > > > On Wed, Mar 30, 2022 at 10:48:12AM -0400, Paul Moore wrote: > > > > > > > > If audit is not generating SYSCALL records, even for invalid/ENOSYS > > > > > > > > syscalls, I would consider that a bug which should be fixed. > > > > > > > > > > > > > > If we fix this bug, do you think audit invalid/ENOSYS syscalls better > > > > > > > be forcible or be a rule that can be configure? I think configure is > > > > > > > better. > > > > > > > > > > > > It isn't clear to me exactly what you are asking, but I would expect > > > > > > the existing audit syscall filtering mechanism to work regardless if > > > > > > the syscall is valid or not. > > > > > > > > > > Thanks, I try to make it more clear. We found that auditctl would only > > > > > set rule with syscall number (>=0 && <2047) ... > > > > > > That is exactly why I wrote the warning below in my response ... > > > > > I think the question is more clear now. > > > > 1) libaudit.c wants to forbid setting invalid syscall, but inconsistent > > Currently way(>=0 && <2047) is inconsistent, syscall with number 2000 and > > syscall with number 3000 are both invalid syscall. But 2000 can be set by > > auditctl, and 3000 cannot be set by auditctl. > > A better way to do this forbidden is to use __NR_syscalls(asm-generic/unistd.h). > > > > 2) if libaudit.c do the right forbidden, kernel better ignore invalid syscall > > See this patch. > > > > If we want audit invalid syscall as you said before. libaudit.c should not > > do the forbidden, auditctl should allow setting syscall rule with 'any' number. > > So do you think we should fix libaudit.c? > > I'm having a bit of trouble understanding what you've said above. > > The kernel ultimately must protect itself from malice and mistakes, so > it must verify all data sent to it. > > Userspace can help by knowing what that kernel policy is so it can avoid > violating that policy or provide useful feedback if it can't. Userspace > can be used to make things more efficient, but the kernel is the last > step for security. > > If userspace and the kernel are mismatched or out of sync, then the > kernel enforces policy to protect itself. > Much appreciate for your interpretation. Have you get any idea of how to solve the mismatched? From your viewpoint, I think it's better for kernel to not handle syscall of syscall number<0, because it's invaild of all arch, and has no value for attacker to probing for specific syscall numbers. > > > > > > Beware that there are some limitations > > > > > > to the audit syscall filter, which are unfortunately baked into the > > > > > > current design/implementation, which may affect this to some extent. > > > > > > -- > > > paul-moore.com > > - RGB > > -- > Richard Guy Briggs > Sr. S/W Engineer, Kernel Security, Base Operating Systems > Remote, Ottawa, Red Hat Canada > IRC: rgb, SunRaycer > Voice: +1.647.777.2635, Internal: (81) 32635