From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH 1/3] ext4: require key for truncate(2) of encrypted file Date: Fri, 23 Jun 2017 19:52:54 -0400 Message-ID: <20170623235254.l5wyukjiy2mdms3m@thunk.org> References: <20170613234755.111167-1-ebiggers3@gmail.com> <20170613234755.111167-2-ebiggers3@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, Eric Biggers To: Eric Biggers Return-path: Content-Disposition: inline In-Reply-To: <20170613234755.111167-2-ebiggers3@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, Jun 13, 2017 at 04:47:53PM -0700, Eric Biggers wrote: > From: Eric Biggers > > Currently, filesystems allow truncate(2) on an encrypted file without > the encryption key. However, it's impossible to correctly handle the > case where the size being truncated to is not a multiple of the > filesystem block size, because that would require decrypting the final > block, zeroing the part beyond i_size, then encrypting the block. > > As other modifications to encrypted file contents are prohibited without > the key, just prohibit truncate(2) as well, making it fail with ENOKEY. > > Signed-off-by: Eric Biggers Thanks, applied. - Ted