From: Yu Chen Subject: Re: [PATCH 0/4][RFC v2] Introduce the in-kernel hibernation encryption Date: Fri, 3 Aug 2018 11:37:02 +0800 Message-ID: <20180803033702.GB416@sandybridge-desktop> References: <20180718202235.GA4132@amd> <20180718235851.GA22170@sandybridge-desktop> <20180719110149.GA4679@amd> <20180719132003.GA30981@sandybridge-desktop> <20180720102532.GA20284@amd> <1532346156.3057.11.camel@suse.com> <20180723162302.GA4503@sandybridge-desktop> <1532590246.7411.3.camel@suse.com> <20180726081404.GG4244@linux-l9pv.suse> <20180730170415.GQ4244@linux-l9pv.suse> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Oliver Neukum , Pavel Machek , "Rafael J . Wysocki" , Eric Biggers , Theodore Ts o , Stephan Mueller , Denis Kenzior , linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, "Gu, Kookoo" , "Zhang, Rui" To: joeyli Return-path: Content-Disposition: inline In-Reply-To: <20180730170415.GQ4244@linux-l9pv.suse> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Hi Joey, On Tue, Jul 31, 2018 at 01:04:15AM +0800, joeyli wrote: > Hi all, > > On Thu, Jul 26, 2018 at 04:14:04PM +0800, joeyli wrote: > > On Thu, Jul 26, 2018 at 09:30:46AM +0200, Oliver Neukum wrote: > > > On Di, 2018-07-24 at 00:23 +0800, Yu Chen wrote: > > > > > > > > Good point, we once tried to generate key in kernel, but people > > > > suggest to generate key in userspace and provide it to the > > > > kernel, which is what ecryptfs do currently, so it seems this > > > > should also be safe for encryption in kernel. > > > > https://www.spinics.net/lists/linux-crypto/msg33145.html > > > > Thus Chun-Yi's signature can use EFI key and both the key from > > > > user space. > > > > > > Hi, > > > > > > ecryptfs can trust user space. It is supposed to keep data > > > safe while the system is inoperative. The whole point of Secure > > > Boot is a cryptographic system of trust that does not include > > > user space. > > > > > > I seriously doubt we want to use trusted computing here. So the > > > key needs to be generated in kernel space and stored in a safe > > > manner. As we have a saolution doing that, can we come to ausable > > > synthesis? > > > > > > Regards > > > Oliver > > > > Crurently there have two solutions, they are trusted key and EFI key. > > Both of them are generated in kernel and are not visible in user space. > > > > The trusted key is generated by kernel then sealed by the TPM's > > SRK. So the trusted key can be stored in anywhere then be enrolled > > to kernel when we need it. EVM already uses it. > > > > The EFI key is Jiri Kosina's idea. It is stored in boot services > > variable, which means that it can only be access by signed EFI binary > > (e.g. signed EFI boot stub) when secure boot be enabled. SLE applied > > this solution a couple of years. > > > > I am working on put the EFI key to key retention service. Then > > EFI key can be a master key of encrypted key. EVM can also use > > it: > > https://github.com/joeyli/linux-s4sign/commit/bae39460393ada4c0226dd07cd5e3afcef86b71f > > https://github.com/joeyli/linux-s4sign/commit/f552f97cc3cca5acd84f424b7f946ffb5fe8e9ec > > > > That's why I want to use key retention service in hibernation > > encryption/authentication. Which means that we can use key > > API to access trusted key and EFI key. > > > > Here is a proof of concept for using the key retention service > to encrypt/sign snapshot image. It's using EFI key now, I will > add encrypted key support in the key handler later: > https://github.com/joeyli/linux-s4sign/commit/6311e97038974bc5de8121769fb4d34470009566 > Thanks for the work, I have two questions here: 1. Could you please describe a little more about the scenario on how the user could use the secret key for hibernation encryption? A requirement is that, the user should provide a passphrase(for key derivation, i.e.) during resume. I was thinking how user could interact with the security key mechanism here. 2. The generation of secret key in EFI boot environment is using a non standard derivation method in generate_secret_key(), I'm not sure if this is safe enough. This is why we tried to put PBKDF2 into kernel at first and leave it to the user space then. Best, Yu > My next step is that cleaning up the my EFI key type patches and > submit it to EFI/keys subsystem ASAP. Then I will clean up > my hibernation encryption/authentication solution for reviewing. > > Thanks > Joey Lee