From: Kshitiz Varshney <kshitiz.varshney@nxp.com>
To: Jarkko Sakkinen <jarkko@kernel.org>,
David Gstir <david@sigma-star.at>,
Mimi Zohar <zohar@linux.ibm.com>,
James Bottomley <jejb@linux.ibm.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>
Cc: Shawn Guo <shawnguo@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
dl-linux-imx <linux-imx@nxp.com>,
Ahmad Fatoum <a.fatoum@pengutronix.de>,
sigma star Kernel Team <upstream+dcp@sigma-star.at>,
David Howells <dhowells@redhat.com>, Li Yang <leoyang.li@nxp.com>,
Paul Moore <paul@paul-moore.com>,
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"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
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<linux-security-module@vger.kernel.org>,
Richard Weinberger <richard@nod.at>,
David Oberhollenzer <david.oberhollenzer@sigma-star.at>,
Varun Sethi <V.Sethi@nxp.com>, Gaurav Jain <gaurav.jain@nxp.com>,
Pankaj Gupta <pankaj.gupta@nxp.com>
Subject: RE: [EXT] Re: [PATCH v8 6/6] docs: trusted-encrypted: add DCP as new trust source
Date: Tue, 9 Apr 2024 09:48:27 +0000 [thread overview]
Message-ID: <DB6PR04MB3190F6B78FF3760EBCC14E758F072@DB6PR04MB3190.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <D0ALT2QCUIYB.8NFTE7Z18JKN@kernel.org>
Hi Jarkko,
> -----Original Message-----
> From: Jarkko Sakkinen <jarkko@kernel.org>
> Sent: Wednesday, April 3, 2024 9:18 PM
> To: David Gstir <david@sigma-star.at>; Mimi Zohar <zohar@linux.ibm.com>;
> James Bottomley <jejb@linux.ibm.com>; Herbert Xu
> <herbert@gondor.apana.org.au>; David S. Miller <davem@davemloft.net>
> Cc: Shawn Guo <shawnguo@kernel.org>; Jonathan Corbet
> <corbet@lwn.net>; Sascha Hauer <s.hauer@pengutronix.de>; Pengutronix
> Kernel Team <kernel@pengutronix.de>; Fabio Estevam
> <festevam@gmail.com>; dl-linux-imx <linux-imx@nxp.com>; Ahmad Fatoum
> <a.fatoum@pengutronix.de>; sigma star Kernel Team
> <upstream+dcp@sigma-star.at>; David Howells <dhowells@redhat.com>; Li
> Yang <leoyang.li@nxp.com>; Paul Moore <paul@paul-moore.com>; James
> Morris <jmorris@namei.org>; Serge E. Hallyn <serge@hallyn.com>; Paul E.
> McKenney <paulmck@kernel.org>; Randy Dunlap <rdunlap@infradead.org>;
> Catalin Marinas <catalin.marinas@arm.com>; Rafael J. Wysocki
> <rafael.j.wysocki@intel.com>; Tejun Heo <tj@kernel.org>; Steven Rostedt
> (Google) <rostedt@goodmis.org>; linux-doc@vger.kernel.org; linux-
> kernel@vger.kernel.org; linux-integrity@vger.kernel.org;
> keyrings@vger.kernel.org; linux-crypto@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linuxppc-dev@lists.ozlabs.org; linux-security-
> module@vger.kernel.org; Richard Weinberger <richard@nod.at>; David
> Oberhollenzer <david.oberhollenzer@sigma-star.at>
> Subject: [EXT] Re: [PATCH v8 6/6] docs: trusted-encrypted: add DCP as new
> trust source
>
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report
> this email' button
>
>
> On Wed Apr 3, 2024 at 10:21 AM EEST, David Gstir wrote:
> > Update the documentation for trusted and encrypted KEYS with DCP as
> > new trust source:
> >
> > - Describe security properties of DCP trust source
> > - Describe key usage
> > - Document blob format
> >
> > Co-developed-by: Richard Weinberger <richard@nod.at>
> > Signed-off-by: Richard Weinberger <richard@nod.at>
> > Co-developed-by: David Oberhollenzer
> > <david.oberhollenzer@sigma-star.at>
> > Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
> > Signed-off-by: David Gstir <david@sigma-star.at>
> > ---
> > .../security/keys/trusted-encrypted.rst | 53 +++++++++++++++++++
> > security/keys/trusted-keys/trusted_dcp.c | 19 +++++++
> > 2 files changed, 72 insertions(+)
> >
> > diff --git a/Documentation/security/keys/trusted-encrypted.rst
> > b/Documentation/security/keys/trusted-encrypted.rst
> > index e989b9802f92..f4d7e162d5e4 100644
> > --- a/Documentation/security/keys/trusted-encrypted.rst
> > +++ b/Documentation/security/keys/trusted-encrypted.rst
> > @@ -42,6 +42,14 @@ safe.
> > randomly generated and fused into each SoC at manufacturing time.
> > Otherwise, a common fixed test key is used instead.
> >
> > + (4) DCP (Data Co-Processor: crypto accelerator of various i.MX
> > + SoCs)
> > +
> > + Rooted to a one-time programmable key (OTP) that is generally
> burnt
> > + in the on-chip fuses and is accessible to the DCP encryption engine
> only.
> > + DCP provides two keys that can be used as root of trust: the OTP
> key
> > + and the UNIQUE key. Default is to use the UNIQUE key, but selecting
> > + the OTP key can be done via a module parameter
> (dcp_use_otp_key).
> > +
> > * Execution isolation
> >
> > (1) TPM
> > @@ -57,6 +65,12 @@ safe.
> >
> > Fixed set of operations running in isolated execution environment.
> >
> > + (4) DCP
> > +
> > + Fixed set of cryptographic operations running in isolated execution
> > + environment. Only basic blob key encryption is executed there.
> > + The actual key sealing/unsealing is done on main processor/kernel
> space.
> > +
> > * Optional binding to platform integrity state
> >
> > (1) TPM
> > @@ -79,6 +93,11 @@ safe.
> > Relies on the High Assurance Boot (HAB) mechanism of NXP SoCs
> > for platform integrity.
> >
> > + (4) DCP
> > +
> > + Relies on Secure/Trusted boot process (called HAB by vendor) for
> > + platform integrity.
> > +
> > * Interfaces and APIs
> >
> > (1) TPM
> > @@ -94,6 +113,11 @@ safe.
> >
> > Interface is specific to silicon vendor.
> >
> > + (4) DCP
> > +
> > + Vendor-specific API that is implemented as part of the DCP crypto
> driver in
> > + ``drivers/crypto/mxs-dcp.c``.
> > +
> > * Threat model
> >
> > The strength and appropriateness of a particular trust source
> > for a given @@ -129,6 +153,13 @@ selected trust source:
> > CAAM HWRNG, enable CRYPTO_DEV_FSL_CAAM_RNG_API and ensure
> the device
> > is probed.
> >
> > + * DCP (Data Co-Processor: crypto accelerator of various i.MX SoCs)
> > +
> > + The DCP hardware device itself does not provide a dedicated RNG
> interface,
> > + so the kernel default RNG is used. SoCs with DCP like the i.MX6ULL do
> have
> > + a dedicated hardware RNG that is independent from DCP which can be
> enabled
> > + to back the kernel RNG.
> > +
> > Users may override this by specifying ``trusted.rng=kernel`` on the
> > kernel command-line to override the used RNG with the kernel's random
> number pool.
> >
> > @@ -231,6 +262,19 @@ Usage::
> > CAAM-specific format. The key length for new keys is always in bytes.
> > Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
> >
> > +Trusted Keys usage: DCP
> > +-----------------------
> > +
> > +Usage::
> > +
> > + keyctl add trusted name "new keylen" ring
> > + keyctl add trusted name "load hex_blob" ring
> > + keyctl print keyid
> > +
> > +"keyctl print" returns an ASCII hex copy of the sealed key, which is
> > +in format specific to this DCP key-blob implementation. The key
> > +length for new keys is always in bytes. Trusted Keys can be 32 - 128 bytes
> (256 - 1024 bits).
> > +
> > Encrypted Keys usage
> > --------------------
> >
> > @@ -426,3 +470,12 @@ string length.
> > privkey is the binary representation of TPM2B_PUBLIC excluding the
> > initial TPM2B header which can be reconstructed from the ASN.1 octed
> > string length.
> > +
> > +DCP Blob Format
> > +---------------
> > +
> > +.. kernel-doc:: security/keys/trusted-keys/trusted_dcp.c
> > + :doc: dcp blob format
> > +
> > +.. kernel-doc:: security/keys/trusted-keys/trusted_dcp.c
> > + :identifiers: struct dcp_blob_fmt
> > diff --git a/security/keys/trusted-keys/trusted_dcp.c
> > b/security/keys/trusted-keys/trusted_dcp.c
> > index 16c44aafeab3..b5f81a05be36 100644
> > --- a/security/keys/trusted-keys/trusted_dcp.c
> > +++ b/security/keys/trusted-keys/trusted_dcp.c
> > @@ -19,6 +19,25 @@
> > #define DCP_BLOB_VERSION 1
> > #define DCP_BLOB_AUTHLEN 16
> >
> > +/**
> > + * DOC: dcp blob format
> > + *
> > + * The Data Co-Processor (DCP) provides hardware-bound AES keys using
> > +its
> > + * AES encryption engine only. It does not provide direct key
> sealing/unsealing.
> > + * To make DCP hardware encryption keys usable as trust source, we
> > +define
> > + * our own custom format that uses a hardware-bound key to secure the
> > +sealing
> > + * key stored in the key blob.
> > + *
> > + * Whenever a new trusted key using DCP is generated, we generate a
> > +random 128-bit
> > + * blob encryption key (BEK) and 128-bit nonce. The BEK and nonce are
> > +used to
> > + * encrypt the trusted key payload using AES-128-GCM.
> > + *
> > + * The BEK itself is encrypted using the hardware-bound key using the
> > +DCP's AES
> > + * encryption engine with AES-128-ECB. The encrypted BEK, generated
> > +nonce,
> > + * BEK-encrypted payload and authentication tag make up the blob
> > +format together
> > + * with a version number, payload length and authentication tag.
> > + */
> > +
> > /**
> > * struct dcp_blob_fmt - DCP BLOB format.
> > *
>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
>
> I can only test that this does not break a machine without the hardware
> feature.
>
> Is there anyone who could possibly peer test these patches?
I am already working on testing this patchset on i.MX6 platform.
Regards,
Kshitiz
> BR, Jarkko
next prev parent reply other threads:[~2024-04-09 9:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-03 7:21 [PATCH v8 0/6] DCP as trusted keys backend David Gstir
2024-04-03 7:21 ` [PATCH v8 1/6] crypto: mxs-dcp: Add support for hardware-bound keys David Gstir
2024-04-03 7:21 ` [PATCH v8 2/6] KEYS: trusted: improve scalability of trust source config David Gstir
2024-04-03 7:21 ` [PATCH v8 3/6] KEYS: trusted: Introduce NXP DCP-backed trusted keys David Gstir
2024-04-09 10:54 ` [EXT] " Kshitiz Varshney
2024-04-09 17:27 ` Ahmad Fatoum
2024-04-10 7:13 ` Kshitiz Varshney
2024-04-03 7:21 ` [PATCH v8 4/6] MAINTAINERS: add entry for DCP-based " David Gstir
2024-04-03 7:21 ` [PATCH v8 5/6] docs: document DCP-backed trusted keys kernel params David Gstir
2024-04-03 7:21 ` [PATCH v8 6/6] docs: trusted-encrypted: add DCP as new trust source David Gstir
2024-04-03 13:24 ` Bagas Sanjaya
2024-04-03 15:47 ` Jarkko Sakkinen
2024-04-09 9:48 ` Kshitiz Varshney [this message]
[not found] ` < <DB6PR04MB3190F6B78FF3760EBCC14E758F072@DB6PR04MB3190.eurprd04.prod.outlook.com>
2024-04-13 21:24 ` [EXT] " Jarkko Sakkinen
2024-04-29 11:35 ` [EXT] " David Gstir
2024-04-30 11:48 ` Kshitiz Varshney
2024-04-30 12:03 ` David Gstir
2024-05-03 23:45 ` Jarkko Sakkinen
2024-04-12 6:26 ` Herbert Xu
2024-04-13 21:44 ` Jarkko Sakkinen
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