Subject: Re: [PATCH v5 0/6] DCP as trusted keys backend

From: Richard Weinberger <[email-masked]>
Date: Sun, 25 Feb 2024 23:20:31 +0100

Mimi, James, Jarkko, David,

you remained silent for a whole release cycle.
Is there anything we can do to get this forward?

Thanks,
//richard

Am Dienstag, 13. Februar 2024, 10:59:56 CET schrieb Richard Weinberger:
> Am Montag, 5. Februar 2024, 09:39:07 CET schrieb David Gstir:
> > Hi,
> > 
> > > On 15.12.2023, at 12:06, David Gstir <[email-masked]> wrote:
> > > 
> > > This is a revival of the previous patch set submitted by Richard Weinberger:
> > > https://lore.kernel.org/linux-integrity/[email-masked]/
> > > 
> > > v4 is here:
> > > https://lore.kernel.org/keyrings/[email-masked]/
> > > 
> > > v4 -> v5:
> > > - Make Kconfig for trust source check scalable as suggested by Jarkko Sakkinen
> > > - Add Acked-By from Herbert Xu to patch #1 - thanks!
> > > v3 -> v4:
> > > - Split changes on MAINTAINERS and documentation into dedicated patches
> > > - Use more concise wording in commit messages as suggested by Jarkko Sakkinen
> > > v2 -> v3:
> > > - Addressed review comments from Jarkko Sakkinen
> > > v1 -> v2:
> > > - Revive and rebase to latest version
> > > - Include review comments from Ahmad Fatoum
> > > 
> > > The Data CoProcessor (DCP) is an IP core built into many NXP SoCs such
> > > as i.mx6ull.
> > > 
> > > Similar to the CAAM engine used in more powerful SoCs, DCP can AES-
> > > encrypt/decrypt user data using a unique, never-disclosed,
> > > device-specific key. Unlike CAAM though, it cannot directly wrap and
> > > unwrap blobs in hardware. As DCP offers only the bare minimum feature
> > > set and a blob mechanism needs aid from software. A blob in this case
> > > is a piece of sensitive data (e.g. a key) that is encrypted and
> > > authenticated using the device-specific key so that unwrapping can only
> > > be done on the hardware where the blob was wrapped.
> > > 
> > > This patch series adds a DCP based, trusted-key backend and is similar
> > > in spirit to the one by Ahmad Fatoum [0] that does the same for CAAM.
> > > It is of interest for similar use cases as the CAAM patch set, but for
> > > lower end devices, where CAAM is not available.
> > > 
> > > Because constructing and parsing the blob has to happen in software,
> > > we needed to decide on a blob format and chose the following:
> > > 
> > > struct dcp_blob_fmt {
> > > __u8 fmt_version;
> > > __u8 blob_key[AES_KEYSIZE_128];
> > > __u8 nonce[AES_KEYSIZE_128];
> > > __le32 payload_len;
> > > __u8 payload[];
> > > } __packed;
> > > 
> > > The `fmt_version` is currently 1.
> > > 
> > > The encrypted key is stored in the payload area. It is AES-128-GCM
> > > encrypted using `blob_key` and `nonce`, GCM auth tag is attached at
> > > the end of the payload (`payload_len` does not include the size of
> > > the auth tag).
> > > 
> > > The `blob_key` itself is encrypted in AES-128-ECB mode by DCP using
> > > the OTP or UNIQUE device key. A new `blob_key` and `nonce` are generated
> > > randomly, when sealing/exporting the DCP blob.
> > > 
> > > This patchset was tested with dm-crypt on an i.MX6ULL board.
> > > 
> > > [0] https://lore.kernel.org/keyrings/[email-masked]/
> > > 
> > > David Gstir (6):
> > >  crypto: mxs-dcp: Add support for hardware-bound keys
> > >  KEYS: trusted: improve scalability of trust source config
> > >  KEYS: trusted: Introduce NXP DCP-backed trusted keys
> > >  MAINTAINERS: add entry for DCP-based trusted keys
> > >  docs: document DCP-backed trusted keys kernel params
> > >  docs: trusted-encrypted: add DCP as new trust source
> > > 
> > > .../admin-guide/kernel-parameters.txt         |  13 +
> > > .../security/keys/trusted-encrypted.rst       |  85 +++++
> > > MAINTAINERS                                   |   9 +
> > > drivers/crypto/mxs-dcp.c                      | 104 +++++-
> > > include/keys/trusted_dcp.h                    |  11 +
> > > include/soc/fsl/dcp.h                         |  17 +
> > > security/keys/trusted-keys/Kconfig            |  18 +-
> > > security/keys/trusted-keys/Makefile           |   2 +
> > > security/keys/trusted-keys/trusted_core.c     |   6 +-
> > > security/keys/trusted-keys/trusted_dcp.c      | 311 ++++++++++++++++++
> > > 10 files changed, 562 insertions(+), 14 deletions(-)
> > > create mode 100644 include/keys/trusted_dcp.h
> > > create mode 100644 include/soc/fsl/dcp.h
> > > create mode 100644 security/keys/trusted-keys/trusted_dcp.c
> > 
> > Jarkko, Mimi, David do you need anything from my side for these patches to get them merged?
> 
> Friendly ping also from my side. :-)
> 
> Thanks,
> //richard
> 
> -- 
> sigma star gmbh | Eduard-Bodem-Gasse 6, 6020 Innsbruck, AUT
> UID/VAT Nr: ATU 66964118 | FN: 374287y
> 

-- 
 sigma star gmbh | Eduard-Bodem-Gasse 6, 6020 Innsbruck, AUT
UID/VAT Nr: ATU 66964118 | FN: 374287y