From owner-svn-src-head@freebsd.org Fri Apr 14 20:57:25 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0D4ADD3E3BE; Fri, 14 Apr 2017 20:57:25 +0000 (UTC) (envelope-from delphij@gmail.com) Received: from mail-oi0-x22c.google.com (mail-oi0-x22c.google.com [IPv6:2607:f8b0:4003:c06::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id C3561E51; Fri, 14 Apr 2017 20:57:24 +0000 (UTC) (envelope-from delphij@gmail.com) Received: by mail-oi0-x22c.google.com with SMTP id f22so100861290oib.2; Fri, 14 Apr 2017 13:57:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=LsQ9R81ymmjNdMlanNSo9alSr4oIT8XWYPIgpRLGJtw=; b=AtSIxN/u3DXnd3vgXZgJtmOGAGUYKnOll1eBraLKlK7lgbX5pg4r0vTbN23NpLsqit HB62p7f7vWc0njpkGL9MlsCWgmFk6I1mE/YI0kCNbhL6zagiMcwJvA7DWG6OUcQFcC/5 tuB++aBFkyeoG5hNUuzn1s7MzTvXDBA3+RNXwXPa4xPXt4pGt0vVHFELyHO0BUP8nntD UCHP6XH3UPEedFvHH6Re9yHaLcGW8BBfSesOckl7dMC2BtUrI6joKHD4xw/5QTrlJk/G jR/k6RXesEM8oRZWAXZDctJMtc3mdZNrjdQ8JVMu9fc3yttiv/kez/JMQ1agGWQi5Hls ljDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=LsQ9R81ymmjNdMlanNSo9alSr4oIT8XWYPIgpRLGJtw=; b=SFHd656iL7qCgIkQmjhuiPM6CG1b2vLuAVsU36F/Bg2Cq0BAGRukKcSA/3HTSWczNj 8wJd+2p8ZqNrcIOexppo3ifO3clCKN/z9xqlG/N2GsOxHPNwctBcesPHiJFD0y2+8FJT mb/XAX3tpZBbOw9hh5HO7HZYJntTGz5dR3CFSMvR4lP0XoKNZpJofOCyT4Q78IfXLwyT 9zg/jD2Xf5DLfTmd7KdeDGDrfjCamrpGL5hNiTgUmTr7JNjZkTb2gXjr4k8z9Qye9Os7 cp9nmPl0ph26K8q7bNP/+wf0cDw3MDzkSJ78acj1y0i40X99FrZMRfJwetjfRCLyEGr2 TCuw== X-Gm-Message-State: AN3rC/7/BZlryhIlG++FRyIVqtghgEi+DqXGa+ltF5oGJdYCOpVpNY7G +qjtW1rDntpujzDtC1J9Pprg/5pajQac X-Received: by 10.202.215.67 with SMTP id o64mr5480427oig.83.1492203443948; Fri, 14 Apr 2017 13:57:23 -0700 (PDT) MIME-Version: 1.0 Received: by 10.157.63.179 with HTTP; Fri, 14 Apr 2017 13:57:23 -0700 (PDT) In-Reply-To: References: <201704141941.v3EJfmCW003347@repo.freebsd.org> <20170414202918.GD5039@wkstn-mjohnston.west.isilon.com> From: Xin LI Date: Fri, 14 Apr 2017 13:57:23 -0700 Message-ID: Subject: Re: svn commit: r316938 - head/sbin/savecore To: Ronald Klop Cc: Alan Somers , Mark Johnston , "svn-src-head@freebsd.org" , "svn-src-all@freebsd.org" , "src-committers@freebsd.org" , Ngie Cooper Content-Type: text/plain; charset=UTF-8 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Apr 2017 20:57:25 -0000 No, this is not the threat model for swaps. On Fri, Apr 14, 2017 at 1:47 PM, Ronald Klop wrote: > On Fri, 14 Apr 2017 22:29:18 +0200, Mark Johnston wrote: > >> On Fri, Apr 14, 2017 at 01:49:51PM -0600, Alan Somers wrote: >>> >>> On Fri, Apr 14, 2017 at 1:41 PM, Ngie Cooper wrote: >>> > Author: ngie >>> > Date: Fri Apr 14 19:41:48 2017 >>> > New Revision: 316938 >>> > URL: https://svnweb.freebsd.org/changeset/base/316938 >>> > >>> > Log: >>> > savecore: fix space calculation with respect to `minfree` in >>> > check_space(..) >>> > >>> > - Use strtoll(3) instead of atoi(3), because atoi(3) limits the >>> > representable data to INT_MAX. Check the values received from >>> > strtoll(3), trimming trailing whitespace off the end to maintain >>> > POLA. >>> > - Use `KiB` instead of `kB` when describing free space, total space, >>> > etc. I am now fully aware of `KiB` being the IEC standard for 1024 >>> > bytes and `kB` being the IEC standard for 1000 bytes. >>> > - Store available number of KiB in `available` so it can be more >>> > easily queried and compared to ensure that there are enough KiB to >>> > store the dump image on disk. >>> > - Print out the reserved space on disk, per `minfree`, so end-users >>> > can troubleshoot why check_space(..) is reporting that there isn't >>> > enough free space. >>> > >>> > MFC after: 7 weeks >>> > Reviewed by: Anton Rang (earlier diff), cem (earlier >>> > diff) >>> > Tested with: positive/negative cases (see review); make tinderbox >>> > Sponsored by: Dell EMC Isilon >>> > Differential Revision: D10379 >>> >>> The free space calculation is still uselessly conservative, because it >>> doesn't account for the fact that core dumps will always be either >>> spare or compressed. The result is that savecore will frequently >>> refuse to save corefiles even when there's plenty of space. I >>> proposed removing the space check altogether in >>> https://reviews.freebsd.org/D2587. However, I agreed to wait until >>> after the compressed core dump feature was merged, because then mostly >>> accurate space checks will be possible. AFAIK the compressed core >>> dump feature still hasn't been finished. >> >> >> I had held off on it for a while because it was going to conflict with >> the work to add encrypted dump support, which of course has finished. >> >> The patch to add compression support is here and should largely still >> work: >> >> https://people.freebsd.org/~markj/patches/core-compression/20141110-kern_dump.diff >> >> I've been hesitant about pushing it forward: >> - The dump_write* APIs need some simplification after the addition of >> encrypted dump support and support for dumping to 4Kn drives. >> - I'm not sure how encryption should compose with compression. It seems >> intuitively obvious that we should compress before encrypting if the >> compression is to be of any use, but I don't know enough to know >> whether the compression might somehow compromise the effectiveness of >> the encryption. >> >> If anyone has some insight on the second of these two points, I'd >> appreciate hearing it. > > > About compression before encryption there is some information. For example: > https://en.wikipedia.org/wiki/CRIME > Openssh removed compression in pre-authentication in > http://www.openssh.com/txt/release-7.4 > > Regards, > Ronald. >