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=1.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 01AB6C4360F for ; Mon, 18 Mar 2019 23:08:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C43662175B for ; Mon, 18 Mar 2019 23:08:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552950515; bh=yaB68QR3BXIzS0jW8UvCblXcYCpbjRQp3yuZ8DGGTpc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=U99Ywpd4RZSBIqryJYBSGSDZB+l+EZmsTEGAROm+4o4LaXTT+9vBhhQXzNdUPzeCm 0Hu9OAuUXYUj07BQM8N4as+5aaV9djYX575bTTd79cvlpe25b7TIA1CZEgnIb8DvBL JJ4Vr8coUgZpBH8xHXolIRNfmP7eaGWJgOR4TIlk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726927AbfCRXIe (ORCPT ); Mon, 18 Mar 2019 19:08:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:34692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726326AbfCRXIe (ORCPT ); Mon, 18 Mar 2019 19:08:34 -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 124CC2171F; Mon, 18 Mar 2019 23:08:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552950513; bh=yaB68QR3BXIzS0jW8UvCblXcYCpbjRQp3yuZ8DGGTpc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fVuP1bwp4qmwXuBEvQMzUcBL0DEML8mQuvOZjDIbo/hmgqOFAq7vxSswNifRzfR0S va+BLDsDjL4v+yCLWDNFQ/b10o7IhvPcrbIucRrLwNQP/dq0vijSHsN/NhZzjuaJTy +X/Krnpq3t96XnzWfpFjU0mupEVoaHUvA3St6n9U= Date: Mon, 18 Mar 2019 16:08:31 -0700 From: Eric Biggers To: Richard Weinberger Cc: linux-fscrypt@vger.kernel.org, Satya Tangirala , "open list:ABI/API" , linux-f2fs-devel@lists.sourceforge.net, keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, linux-crypto@vger.kernel.org, linux-fsdevel , linux-ext4@vger.kernel.org, Paul Crowley Subject: Re: [RFC PATCH v3 07/18] fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl Message-ID: <20190318230830.GA40545@gmail.com> References: <20190220065249.32099-1-ebiggers@kernel.org> <20190221054938.GA12467@sol.localdomain> <2024630.T9XyBPH5Ub@blindfold> <20190221184203.GB140206@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190221184203.GB140206@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 Hi Richard, On Thu, Feb 21, 2019 at 10:42:03AM -0800, Eric Biggers wrote: > On Thu, Feb 21, 2019 at 10:33:12AM +0100, Richard Weinberger wrote: > > Eric, > > > > Am Donnerstag, 21. Februar 2019, 06:49:39 CET schrieb Eric Biggers: > > > Hi Richard, > > > > > > On Thu, Feb 21, 2019 at 12:52:38AM +0100, Richard Weinberger wrote: > > > > On Wed, Feb 20, 2019 at 7:55 AM Eric Biggers wrote: > > > > > +#define FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE \ > > > > > + (CONST_STRLEN("fscrypt-") + FIELD_SIZEOF(struct super_block, s_id)) > > > > > + > > > > > +#define FSCRYPT_MK_DESCRIPTION_SIZE (2 * FSCRYPT_KEY_DESCRIPTOR_SIZE + 1) > > > > > + > > > > > +static void format_fs_keyring_description( > > > > > + char description[FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE], > > > > > + const struct super_block *sb) > > > > > +{ > > > > > + sprintf(description, "fscrypt-%s", sb->s_id); > > > > > +} > > > > > > > > I fear ->s_id is not the right thing. > > > > For filesystems such as ext4 ->s_id is the name of the backing block device, > > > > so it is per filesysem instance unique. > > > > But this is not guaranteed. For UBIFS ->s_id is just "ubifs", always. > > > > So the names will clash. > > > > > > > > > > What name do you suggest using for UBIFS filesystems? The keyring name could be > > > set by the filesystem via a fscrypt_operations callback if needed. > > > > IMHO the BDI name should be used. I tried using sb->s_bdi->name, but it's still "ubifs" for all UBIFS filesystems. Perhaps there's a way you can make ->s_id for UBIFS unique? There are already existing places that log ->s_id, so perhaps you should do it anyway regardless of this patchset? > > > > > Note that the keyring name isn't particularly important, since the ioctls will > > > work regardless. But we might as well choose something logical, since the > > > keyring name will still show up in /proc/keys. > > > > I'm not done with reviewing your patches, but will it be possible to use keyctl? > > For the a unique name is helpful. :) > > > > Not for adding keys, removing keys, or getting a key's status -- those are what > the ioctls are for. > > See e.g. the discussion in patch 7 ("fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY > ioctl") for why the keyrings syscalls are a poor fit for fscrypt. > Anyway, perhaps I should reconsider whether fscrypt should even use the keyrings subsystem at all, even just "internally", as its quirks still leak out a bit. I'd prefer a nice clean API without any quirks like having to name the keyrings and assign SELinux labels to the keys just to make the keyrings subsystem happy. - Eric