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Message-ID: <64c41aa5ba9ac_a88b29494@dwillia2-xfh.jf.intel.com.notmuch>
Date: Fri, 28 Jul 2023 12:44:37 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Jarkko Sakkinen <jarkko@...nel.org>,
Dan Williams <dan.j.williams@...el.com>, <dhowells@...hat.com>
CC: Brijesh Singh <brijesh.singh@....com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
Peter Zijlstra <peterz@...radead.org>,
Tom Lendacky <thomas.lendacky@....com>,
"Dionna Amalie Glaze" <dionnaglaze@...gle.com>,
Borislav Petkov <bp@...en8.de>,
Samuel Ortiz <sameo@...osinc.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
<linux-coco@...ts.linux.dev>, <keyrings@...r.kernel.org>,
<x86@...nel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/4] keys: Introduce a keys frontend for attestation
reports
Jarkko Sakkinen wrote:
> On Fri Jul 28, 2023 at 7:30 PM UTC, Dan Williams wrote:
> > The bulk of the justification for this patch kit is in "[PATCH 1/4]
>
> /patch kit/patch set/
>
> > keys: Introduce tsm keys". The short summary is that the current
> > approach of adding new char devs and new ioctls, for what amounts to the
> > same functionality with minor formatting differences across vendors, is
> > untenable. Common concepts and the community benefit from common
> > infrastructure.
> >
> > Use Keys to build common infrastructure for confidential computing
>
> /Keys/Linux keyring/
>
> > attestation report blobs, convert sevguest to use it (leaving the
> > deprecation question alone for now), and pave the way for tdx-guest and
> > the eventual risc-v equivalent to use it in lieu of new ioctls.
> >
> > The sevguest conversion is only compile-tested.
> >
> > This submission is To:David since he needs to sign-off on the idea of a
> > new Keys type, the rest is up to the confidential-computing driver
> > maintainers to adopt.
> >
> > Changes from / credit for internal review:
> > - highlight copy_{to,from}_sockptr() as a common way to mix
> > copy_user() and memcpy() paths (Andy)
> > - add MODULE_DESCRIPTION() (Andy)
> > - clarify how the user-defined portion blob might be used (Elena)
> > - clarify the key instantiation options (Sathya)
> > - drop usage of a list for registering providers (Sathya)
> > - drop list.h include from tsm.h (Andy)
> > - add a comment for how TSM_DATA_MAX was derived (Andy)
> > - stop open coding kmemdup_nul() (Andy)
> > - add types.h to tsm.h (Andy)
> > - fix punctuation in comment (Andy)
> > - reorder security/keys/Makefile (Andy)
> > - add some missing includes to tsm.c (Andy)
> > - undo an 81 column clang-format line break (Andy)
> > - manually reflow tsm_token indentation (Andy)
> > - move allocations after input validation in tsm_instantiate() (Andy)
> > - switch to bin2hex() in tsm_read() (Andy)
> > - move init/exit declarations next to their functions (Andy)
> >
> >
> > ---
> >
> > Dan Williams (4):
> > keys: Introduce tsm keys
> > virt: sevguest: Prep for kernel internal {get,get_ext}_report()
> > mm/slab: Add __free() support for kvfree
> > virt: sevguest: Add TSM key support for SNP_{GET,GET_EXT}_REPORT
> >
> >
> > drivers/virt/coco/sev-guest/Kconfig | 2
> > drivers/virt/coco/sev-guest/sev-guest.c | 135 ++++++++++++++-
> > include/keys/tsm.h | 71 ++++++++
> > include/linux/slab.h | 2
> > security/keys/Kconfig | 12 +
> > security/keys/Makefile | 1
> > security/keys/tsm.c | 282 +++++++++++++++++++++++++++++++
> > 7 files changed, 494 insertions(+), 11 deletions(-)
> > create mode 100644 include/keys/tsm.h
> > create mode 100644 security/keys/tsm.c
> >
> > base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5
>
> So how does this scale? Does it scale to TDX, SGX, TPM's or even TEE's
> (ARM SM, RISC-V Keystone etc.). I'm not sure about the scope but we want
> of course something that adapts to multiple use cases, right?
TPMs and TEEs are covered by trusted-keys. I do think a "TSM" flavor of
trusted-keys is in scope for where some of these implementations are
headed, but that comes later. I talk about that in the changelog that
functionality like SNP_GET_DERIVED_KEY likely wants to have a
trusted-keys frontend and not isolated behind a vendor-specific ioctl
interface.
This facility is different, it is just aiming to unify this attestation
report flow. It scales to any driver that can provide the ->auth_new()
operation. I have the sev-guest conversion in this set, and Sathya has
tested this with tdx-guest. I am hoping Samuel can evaluate it for
cove-guest or whatever that driver ends up being called.
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