From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Theodore Ts'o" Subject: Re: [PATCH v4 14/16] ext4: add basic fs-verity support Date: Sat, 15 Jun 2019 11:31:12 -0400 Message-ID: <20190615153112.GO6142@mit.edu> References: <20190606155205.2872-1-ebiggers@kernel.org> <20190606155205.2872-15-ebiggers@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hcAeP-0000of-2g for linux-f2fs-devel@lists.sourceforge.net; Sat, 15 Jun 2019 15:31:29 +0000 Received: from outgoing-auth-1.mit.edu ([18.9.28.11] helo=outgoing.mit.edu) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1hcAeM-00FA6Z-Jb for linux-f2fs-devel@lists.sourceforge.net; Sat, 15 Jun 2019 15:31:28 +0000 Content-Disposition: inline In-Reply-To: <20190606155205.2872-15-ebiggers@kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Eric Biggers Cc: "Darrick J . Wong" , linux-api@vger.kernel.org, Dave Chinner , linux-f2fs-devel@lists.sourceforge.net, linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jaegeuk Kim , linux-integrity@vger.kernel.org, linux-ext4@vger.kernel.org, Linus Torvalds , Christoph Hellwig , Victor Hsieh On Thu, Jun 06, 2019 at 08:52:03AM -0700, Eric Biggers wrote: > +/* > + * Format of ext4 verity xattr. This points to the location of the verity > + * descriptor within the file data rather than containing it directly because > + * the verity descriptor *must* be encrypted when ext4 encryption is used. But, > + * ext4 encryption does not encrypt xattrs. > + */ > +struct fsverity_descriptor_location { > + __le32 version; > + __le32 size; > + __le64 pos; > +}; What's the benefit of storing the location in an xattr as opposed to just keying it off the end of i_size, rounded up to next page size (or 64k) as I had suggested earlier? Using an xattr burns xattr space, which is a limited resource, and it adds some additional code complexity. Does the benefits outweigh the added complexity? - Ted 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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 C6CBDC31E50 for ; Sat, 15 Jun 2019 15:31:29 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9B24521841; Sat, 15 Jun 2019 15:31:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sourceforge.net header.i=@sourceforge.net header.b="S3/kPkp3"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sf.net header.i=@sf.net header.b="JxqeYndN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B24521841 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mit.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-f2fs-devel-bounces@lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.90_1) (envelope-from ) id 1hcAeP-0000py-VJ; Sat, 15 Jun 2019 15:31:29 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hcAeP-0000of-2g for linux-f2fs-devel@lists.sourceforge.net; Sat, 15 Jun 2019 15:31:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=cVucvmhBo9za7coeLbOHm9AhILdFDna2T2fSVBjBSXY=; b=S3/kPkp3owp5y04C45oM3ny9ux DXGdbwez6U+7wgMjbHvBwZWF/HIO96pufLYiQyPCbebKDbuSqSG5sGOi5Gh/d+iuEvoikyhONhH1R MDTcYtXUymK9I9SGO/c9MZHZegslnN3yoAIMc1ZcKW15iJ7RTsb7ltGNQGUptOMLjMWw=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To :From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=cVucvmhBo9za7coeLbOHm9AhILdFDna2T2fSVBjBSXY=; b=JxqeYndNjpYR22n15rA3ueIDvA dzsebySR1wp7GVnqaO0IAWGSY3YM4cerAqwgdvcpJjCrSF6U/Xe62H4zKodm0Ue9xEF2Kv2aYfOWQ Fjq7p7/utYfBCQQfr6tdWLY39locO9C2DcnBKs/7Iks8FntqnLS/X/z8X/m03woqPmL8=; Received: from outgoing-auth-1.mit.edu ([18.9.28.11] helo=outgoing.mit.edu) by sfi-mx-4.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1hcAeM-00FA6Z-Jb for linux-f2fs-devel@lists.sourceforge.net; Sat, 15 Jun 2019 15:31:28 +0000 Received: from callcc.thunk.org (rrcs-74-87-88-165.west.biz.rr.com [74.87.88.165]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x5FFVDgv011825 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sat, 15 Jun 2019 11:31:13 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id CAC77420484; Sat, 15 Jun 2019 11:31:12 -0400 (EDT) Date: Sat, 15 Jun 2019 11:31:12 -0400 From: "Theodore Ts'o" To: Eric Biggers Message-ID: <20190615153112.GO6142@mit.edu> References: <20190606155205.2872-1-ebiggers@kernel.org> <20190606155205.2872-15-ebiggers@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190606155205.2872-15-ebiggers@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Headers-End: 1hcAeM-00FA6Z-Jb Subject: Re: [f2fs-dev] [PATCH v4 14/16] ext4: add basic fs-verity support X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Darrick J . Wong" , linux-api@vger.kernel.org, Dave Chinner , linux-f2fs-devel@lists.sourceforge.net, linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jaegeuk Kim , linux-integrity@vger.kernel.org, linux-ext4@vger.kernel.org, Linus Torvalds , Christoph Hellwig , Victor Hsieh Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net Message-ID: <20190615153112.OaeixKLP2Y8If7iu87hr8MqP3ZLHtmZrl719dBEn4Ys@z> On Thu, Jun 06, 2019 at 08:52:03AM -0700, Eric Biggers wrote: > +/* > + * Format of ext4 verity xattr. This points to the location of the verity > + * descriptor within the file data rather than containing it directly because > + * the verity descriptor *must* be encrypted when ext4 encryption is used. But, > + * ext4 encryption does not encrypt xattrs. > + */ > +struct fsverity_descriptor_location { > + __le32 version; > + __le32 size; > + __le64 pos; > +}; What's the benefit of storing the location in an xattr as opposed to just keying it off the end of i_size, rounded up to next page size (or 64k) as I had suggested earlier? Using an xattr burns xattr space, which is a limited resource, and it adds some additional code complexity. Does the benefits outweigh the added complexity? - Ted _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel