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=-5.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 0E355C433DF for ; Mon, 24 Aug 2020 19:02:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD3F5207D3 for ; Mon, 24 Aug 2020 19:02:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598295745; bh=4xcF3VJfP2pWkLD1MnKiWLH5hBlNe6WvpXlcG9/bUNk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=cbEmDPsZZYmbgNmg8FyXDJ91VtBipL18AoMaFoUGMXUeEJhSqP03Q6Nxtht0rtLDZ 4zl/IU+/kRBw/vJCUScij7THNj/Tt4MjBGf0Yymyt+QDvBPK7B4cB+4agDrOoapR97 L99VStd0f1LNDax3waA0hCe5/jHK5QncDef1AzW0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726666AbgHXTCY (ORCPT ); Mon, 24 Aug 2020 15:02:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:54444 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725963AbgHXTCX (ORCPT ); Mon, 24 Aug 2020 15:02:23 -0400 Received: from gmail.com (unknown [104.132.1.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 02E3B2074D; Mon, 24 Aug 2020 19:02:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598295743; bh=4xcF3VJfP2pWkLD1MnKiWLH5hBlNe6WvpXlcG9/bUNk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pdjxD/lwTwBs8AMDefIpz33YuP0AtYiNyavtRQr7lkpfBZj7RlqkpM378485De4nk WH0Io2eXyxKz4zDfMcK7dt1yFN7UttRHrNEce14Xwaq8moKGEBPL4gFCn/kyTHytpj W4soZI4coKBqQkVSP1hI08dnY7nJ+NgIw/mSNY5g= Date: Mon, 24 Aug 2020 12:02:21 -0700 From: Eric Biggers To: Jeff Layton Cc: linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, ceph-devel@vger.kernel.org Subject: Re: [RFC PATCH 1/8] fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context() Message-ID: <20200824190221.GC1650861@gmail.com> References: <20200824061712.195654-1-ebiggers@kernel.org> <20200824061712.195654-2-ebiggers@kernel.org> <0cf5638796e7cddacc38dcd1e967368b99f0069a.camel@kernel.org> <20200824182114.GB1650861@gmail.com> <06a7d9562b84354eb72bd67c9d4b7262dac53457.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <06a7d9562b84354eb72bd67c9d4b7262dac53457.camel@kernel.org> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Mon, Aug 24, 2020 at 02:47:07PM -0400, Jeff Layton wrote: > On Mon, 2020-08-24 at 11:21 -0700, Eric Biggers wrote: > > On Mon, Aug 24, 2020 at 12:48:48PM -0400, Jeff Layton wrote: > > > > +void fscrypt_hash_inode_number(struct fscrypt_info *ci, > > > > + const struct fscrypt_master_key *mk) > > > > +{ > > > > + WARN_ON(ci->ci_inode->i_ino == 0); > > > > + WARN_ON(!mk->mk_ino_hash_key_initialized); > > > > + > > > > + ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino, > > > > + &mk->mk_ino_hash_key); > > > > > > i_ino is an unsigned long. Will this produce a consistent results on > > > arches with 32 and 64 bit long values? I think it'd be nice to ensure > > > that we can access an encrypted directory created on a 32-bit host from > > > (e.g.) a 64-bit host. > > > > The result is the same regardless of word size and endianness. > > siphash_1u64(v, k) is equivalent to: > > > > __le64 x = cpu_to_le64(v); > > siphash(&x, 8, k); > > > > In the case where you have an (on-storage) inode number that is larger > than 2^32, x will almost certainly be different on a 32 vs. 64-bit > wordsize. > > On the box with the 32-bit wordsize, you'll end up promoting i_ino to a > 64-bit word and the upper 32 bits will be zeroed out. So it seems like > this means that if you're using inline hardware you're going to end up > with a result that won't work correctly across different wordsizes. That's only possible if the VFS is truncating the inode number, which would also break userspace in lots of ways like making applications think that files are hard-linked together when they aren't. Also, IV_INO_LBLK_64 would break. The correct fix for that would be to make inode::i_ino 64-bit. Note that ext4 and f2fs (currently the only filesystems that support the IV_INO_LBLK_* flags) only support 32-bit inode numbers. - Eric