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Ts'o" To: Dave Chinner , linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Satya Tangirala , Paul Crowley , Paul Lawrence , Jaegeuk Kim Message-ID: <20191022133001.GA23268@mit.edu> References: <20191021230355.23136-1-ebiggers@kernel.org> <20191021230355.23136-2-ebiggers@kernel.org> <20191022052712.GA2083@dread.disaster.area> <20191022060004.GA333751@sol.localdomain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191022060004.GA333751@sol.localdomain> User-Agent: Mutt/1.10.1 (2018-07-13) X-Headers-End: 1iMuEw-00BUZR-IN Subject: Re: [f2fs-dev] [PATCH 1/3] fscrypt: add support for inline-encryption-optimized policies 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Mon, Oct 21, 2019 at 11:00:04PM -0700, Eric Biggers wrote: > That won't work because we need consecutive file blocks to have consecutive IVs > as often as possible. The crypto support in the UFS and EMMC standards takes > only a single 64-bit "data unit number" (DUN) per request, which the hardware > uses as the first 64 bits of the IV and automatically increments for each data > unit (i.e. for each filesystem block, in this case). It seems very likely that for systems that are using UFS and eMMC (which are overwhelming lower-end devices --- e.g., embedded and mobile handsets) 32-bit inode and logical block numbers will be just fine. If and when we actually get inline crypto support for server-class systems, hopefully they will support 128-bit DUN's, and/or they will have sufficiently fast key load times such that we can use per-file keying. > An alternative which would work nicely on ext4 and xfs (if xfs supported > fscrypt) would be to pass the physical block number as the DUN. However, that > wouldn't work at all on f2fs because f2fs moves data blocks around. And since > most people who want to use this are using f2fs, f2fs support is essential. And that is something fscrypt supports already, so if people really did want to use 64-bit logical block numbers, they could do that, at the cost of giving up the ability to shrink the file system (which XFS doesn't support anyway....) - Ted _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel