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=-6.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 9DC9CC43219 for ; Tue, 30 Apr 2019 23:08:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66B1B21743 for ; Tue, 30 Apr 2019 23:08:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556665726; bh=J2V4xk+5wKE2yB/A9WdiJV6T4tnAMLRxNPNCtj9jca8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Utp8b9GNi2wnjaCb7gU2BlelrOXWp+YohIO8X+u1QUjct8QM9qLTISJU6KG/SmGsO C8yR7kMA13fv1WhhUBIdp3NkZL8ze1/tFtUuVqa1K4q1cma0MQEmd3VoD6UFjRJ/kC ajVcx93NgOiyi7O4sM/3WY4Vzxu2HphEzzScexyY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726412AbfD3XIp (ORCPT ); Tue, 30 Apr 2019 19:08:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:44402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726086AbfD3XIo (ORCPT ); Tue, 30 Apr 2019 19:08:44 -0400 Received: from gmail.com (unknown [104.132.1.77]) (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 2555520854; Tue, 30 Apr 2019 23:08:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556665723; bh=J2V4xk+5wKE2yB/A9WdiJV6T4tnAMLRxNPNCtj9jca8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SR4PU50IpjiiE/2E7ygI/c9uL7kL9KMoNGzgCg5z3qU8jru7qcuZk795ziPs7WPH0 4CVd4Zp9AjEqAkJ0/IseaPzbsnjVe9UrQgy8/fSDRJqoLohq0S7l8d32G6kxtpoQeo Ea6eqFzFovHvOPkFNhmTsw94caM1sI9DMHL9ap+g= Date: Tue, 30 Apr 2019 16:08:41 -0700 From: Eric Biggers To: Chandan Rajendra Cc: tytso@mit.edu, linux-f2fs-devel@lists.sourceforge.net, hch@infradead.org, linux-fscrypt@vger.kernel.org, adilger.kernel@dilger.ca, linux-fsdevel@vger.kernel.org, jaegeuk@kernel.org, linux-ext4@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH V2 10/13] fscrypt_encrypt_page: Loop across all blocks mapped by a page range Message-ID: <20190430230840.GE48973@gmail.com> References: <20190428043121.30925-1-chandan@linux.ibm.com> <20190428043121.30925-11-chandan@linux.ibm.com> <20190430171133.GC48973@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430171133.GC48973@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Apr 30, 2019 at 10:11:35AM -0700, Eric Biggers wrote: > On Sun, Apr 28, 2019 at 10:01:18AM +0530, Chandan Rajendra wrote: > > For subpage-sized blocks, this commit now encrypts all blocks mapped by > > a page range. > > > > Signed-off-by: Chandan Rajendra > > --- > > fs/crypto/crypto.c | 37 +++++++++++++++++++++++++------------ > > 1 file changed, 25 insertions(+), 12 deletions(-) > > > > diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c > > index 4f0d832cae71..2d65b431563f 100644 > > --- a/fs/crypto/crypto.c > > +++ b/fs/crypto/crypto.c > > @@ -242,18 +242,26 @@ struct page *fscrypt_encrypt_page(const struct inode *inode, > > Need to update the function comment to clearly explain what this function > actually does now. > > > { > > struct fscrypt_ctx *ctx; > > struct page *ciphertext_page = page; > > + int i, page_nr_blks; > > int err; > > > > BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0); > > > > Make a 'blocksize' variable so you don't have to keep calling i_blocksize(). > > Also, you need to check whether 'len' and 'offs' are filesystem-block-aligned, > since the code now assumes it. > > const unsigned int blocksize = i_blocksize(inode); > > if (!IS_ALIGNED(len | offs, blocksize)) > return -EINVAL; > > However, did you check whether that's always true for ubifs? It looks like it > may expect to encrypt a prefix of a block, that is only padded to the next > 16-byte boundary. > > > + page_nr_blks = len >> inode->i_blkbits; > > + > > if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) { > > /* with inplace-encryption we just encrypt the page */ > > - err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page, > > - ciphertext_page, len, offs, > > - gfp_flags); > > - if (err) > > - return ERR_PTR(err); > > - > > + for (i = 0; i < page_nr_blks; i++) { > > + err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, > > + lblk_num, page, > > + ciphertext_page, > > + i_blocksize(inode), offs, > > + gfp_flags); > > + if (err) > > + return ERR_PTR(err); Apparently ubifs does encrypt data shorter than the filesystem block size, so this part is wrong. I suggest we split this into two functions, fscrypt_encrypt_block_inplace() and fscrypt_encrypt_blocks(), so that it's conceptually simpler what each function does. Currently this works completely differently depending on whether the filesystem set FS_CFLG_OWN_PAGES in its fscrypt_operations, which is weird. I also noticed that using fscrypt_ctx for writes seems to be unnecessary. AFAICS, page_private(bounce_page) could point directly to the pagecache page. That would simplify things a lot, especially since then fscrypt_ctx could be removed entirely after you convert reads to use read_callbacks_ctx. IMO, these would be worthwhile cleanups for fscrypt by themselves, without waiting for the read_callbacks stuff to be finalized. Finalizing the read_callbacks stuff will probably require reaching a consensus about how they should work with future filesystem features like fsverity and compression. So to move things forward, I'm considering sending out a series with the above cleanups for fscrypt, plus the equivalent of your patches: "fscrypt_encrypt_page: Loop across all blocks mapped by a page range" "fscrypt_zeroout_range: Encrypt all zeroed out blocks of a page" "Add decryption support for sub-pagesized blocks" (fs/crypto/ part only) Then hopefully we can get all that applied for 5.3 so that fs/crypto/ itself is ready for blocksize != PAGE_SIZE; and get your changes to ext4_bio_write_page(), __ext4_block_zero_page_range(), and ext4_block_write_begin() applied too, so that ext4 is partially ready for encryption with blocksize != PAGE_SIZE. Then only the read_callbacks stuff will remain, to get encryption support into fs/mpage.c and fs/buffer.c. Do you think that's a good plan? Thanks! - Eric