Hi David, > -----Original Message----- > From: David Gstir <david@xxxxxxxxxxxxx> > Sent: Monday, April 29, 2024 5:05 PM > To: Kshitiz Varshney <kshitiz.varshney@xxxxxxx> > Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>; Mimi Zohar > <zohar@xxxxxxxxxxxxx>; James Bottomley <jejb@xxxxxxxxxxxxx>; Herbert > Xu <herbert@xxxxxxxxxxxxxxxxxxx>; David S. Miller > <davem@xxxxxxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>; Jonathan > Corbet <corbet@xxxxxxx>; Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>; > kernel@xxxxxxxxxxxxxx; Fabio Estevam <festevam@xxxxxxxxx>; dl-linux-imx > <linux-imx@xxxxxxx>; Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>; sigma > star Kernel Team <upstream+dcp@xxxxxxxxxxxxx>; David Howells > <dhowells@xxxxxxxxxx>; Li Yang <leoyang.li@xxxxxxx>; Paul Moore > <paul@xxxxxxxxxxxxxx>; James Morris <jmorris@xxxxxxxxx>; Serge E. > Hallyn <serge@xxxxxxxxxx>; Paul E. McKenney <paulmck@xxxxxxxxxx>; > Randy Dunlap <rdunlap@xxxxxxxxxxxxx>; Catalin Marinas > <catalin.marinas@xxxxxxx>; Rafael J. Wysocki > <rafael.j.wysocki@xxxxxxxxx>; Tejun Heo <tj@xxxxxxxxxx>; Steven Rostedt > (Google) <rostedt@xxxxxxxxxxx>; linux-doc@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linux-integrity@xxxxxxxxxxxxxxx; > keyrings@xxxxxxxxxxxxxxx; linux-crypto@xxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; linux-security- > module@xxxxxxxxxxxxxxx; Richard Weinberger <richard@xxxxxx>; David > Oberhollenzer <david.oberhollenzer@xxxxxxxxxxxxx>; Varun Sethi > <V.Sethi@xxxxxxx>; Gaurav Jain <gaurav.jain@xxxxxxx>; Pankaj Gupta > <pankaj.gupta@xxxxxxx> > Subject: Re: [EXT] [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 > > > Hi Kshitiz, > > > On 09.04.2024, at 11:48, Kshitiz Varshney <kshitiz.varshney@xxxxxxx> > wrote: > > > > Hi Jarkko, > > > > > >> -----Original Message----- > >> From: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > >> Sent: Wednesday, April 3, 2024 9:18 PM > >> To: David Gstir <david@xxxxxxxxxxxxx>; Mimi Zohar > >> <zohar@xxxxxxxxxxxxx>; James Bottomley <jejb@xxxxxxxxxxxxx>; > Herbert > >> Xu <herbert@xxxxxxxxxxxxxxxxxxx>; David S. Miller > >> <davem@xxxxxxxxxxxxx> > >> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>; Jonathan Corbet > >> <corbet@xxxxxxx>; Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>; > Pengutronix > >> Kernel Team <kernel@xxxxxxxxxxxxxx>; Fabio Estevam > >> <festevam@xxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>; Ahmad > Fatoum > >> <a.fatoum@xxxxxxxxxxxxxx>; sigma star Kernel Team > >> <upstream+dcp@xxxxxxxxxxxxx>; David Howells <dhowells@xxxxxxxxxx>; > Li > >> Yang <leoyang.li@xxxxxxx>; Paul Moore <paul@xxxxxxxxxxxxxx>; > James > >> Morris <jmorris@xxxxxxxxx>; Serge E. Hallyn <serge@xxxxxxxxxx>; Paul > E. > >> McKenney <paulmck@xxxxxxxxxx>; Randy Dunlap > <rdunlap@xxxxxxxxxxxxx>; > >> Catalin Marinas <catalin.marinas@xxxxxxx>; Rafael J. Wysocki > >> <rafael.j.wysocki@xxxxxxxxx>; Tejun Heo <tj@xxxxxxxxxx>; Steven > >> Rostedt > >> (Google) <rostedt@xxxxxxxxxxx>; linux-doc@xxxxxxxxxxxxxxx; linux- > >> kernel@xxxxxxxxxxxxxxx; linux-integrity@xxxxxxxxxxxxxxx; > >> keyrings@xxxxxxxxxxxxxxx; linux-crypto@xxxxxxxxxxxxxxx; linux-arm- > >> kernel@xxxxxxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; > >> linux-security- module@xxxxxxxxxxxxxxx; Richard Weinberger > >> <richard@xxxxxx>; David Oberhollenzer > >> <david.oberhollenzer@xxxxxxxxxxxxx> > >> 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@xxxxxx> > >>> Signed-off-by: Richard Weinberger <richard@xxxxxx> > >>> Co-developed-by: David Oberhollenzer > >>> <david.oberhollenzer@xxxxxxxxxxxxx> > >>> Signed-off-by: David Oberhollenzer > >>> <david.oberhollenzer@xxxxxxxxxxxxx> > >>> Signed-off-by: David Gstir <david@xxxxxxxxxxxxx> > >>> --- > >>> .../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@xxxxxxxxxx> > >> > >> 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. > > Did you get around to testing this? > I’d greatly appreciate a Tested-by for this. :-) > > Thanks! > BR, David Currently, I am bit busy with other priority activities. It will take time to test this patch set. Regards, Kshitiz
