On Wed, Mar 16, 2022 at 05:43:35PM +0100, Ahmad Fatoum wrote: > The Cryptographic Acceleration and Assurance Module (CAAM) is an IP core > built into many newer i.MX and QorIQ SoCs by NXP. > > The CAAM does crypto acceleration, hardware number generation and > has a blob mechanism for encapsulation/decapsulation of sensitive material. > > This blob mechanism depends on a device specific random 256-bit One Time > Programmable Master Key that is fused in each SoC at manufacturing > time. This key is unreadable and can only be used by the CAAM for AES > encryption/decryption of user data. > > This makes it a suitable backend (source) for kernel trusted keys. > > Previous commits generalized trusted keys to support multiple backends > and added an API to access the CAAM blob mechanism. Based on these, > provide the necessary glue to use the CAAM for trusted keys. > > Reviewed-by: David Gstir <david@xxxxxxxxxxxxx> > Reviewed-by: Pankaj Gupta <pankaj.gupta@xxxxxxx> > Tested-By: Tim Harvey <tharvey@xxxxxxxxxxxxx> > Tested-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx> > Tested-by: Pankaj Gupta <pankaj.gupta@xxxxxxx> > Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > --- > v5 -> v6: > - Rename caam_trusted_key_ops to trusted_key_caam_ops for symmetry > with other trust sources (Pankaj) > - collected Pankaj's Reviewed-by > v4 -> v5: > - Collected Reviewed-by's and Tested-by's > - Changed modifier to SECURE_KEY for compatibility with linux-imx > (Matthias) > v3 -> v4: > - Collected Acked-by's, Reviewed-by's and Tested-by > v2 -> v3: > - add MAINTAINERS entry > v1 -> v2: > - Extend trusted keys documentation for CAAM > > To: Jonathan Corbet <corbet@xxxxxxx> > To: David Howells <dhowells@xxxxxxxxxx> > To: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > To: James Bottomley <jejb@xxxxxxxxxxxxx> > To: Mimi Zohar <zohar@xxxxxxxxxxxxx> > Cc: James Morris <jmorris@xxxxxxxxx> > Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx> > Cc: "Horia Geantă" <horia.geanta@xxxxxxx> > Cc: Aymen Sghaier <aymen.sghaier@xxxxxxx> > Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> > Cc: Eric Biggers <ebiggers@xxxxxxxxxx> > Cc: Jan Luebbe <j.luebbe@xxxxxxxxxxxxxx> > Cc: David Gstir <david@xxxxxxxxxxxxx> > Cc: Richard Weinberger <richard@xxxxxx> > Cc: Franck LENORMAND <franck.lenormand@xxxxxxx> > Cc: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx> > Cc: Sumit Garg <sumit.garg@xxxxxxxxxx> > Cc: keyrings@xxxxxxxxxxxxxxx > Cc: linux-crypto@xxxxxxxxxxxxxxx > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: linux-integrity@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: linux-security-module@xxxxxxxxxxxxxxx > --- > .../admin-guide/kernel-parameters.txt | 1 + > .../security/keys/trusted-encrypted.rst | 40 +++++++++- > MAINTAINERS | 9 +++ > include/keys/trusted_caam.h | 11 +++ > security/keys/trusted-keys/Kconfig | 11 ++- > security/keys/trusted-keys/Makefile | 2 + > security/keys/trusted-keys/trusted_caam.c | 74 +++++++++++++++++++ > security/keys/trusted-keys/trusted_core.c | 6 +- > 8 files changed, 151 insertions(+), 3 deletions(-) > create mode 100644 include/keys/trusted_caam.h > create mode 100644 security/keys/trusted-keys/trusted_caam.c > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 844c883ca9d8..9e7ef4c6585d 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -5875,6 +5875,7 @@ > sources: > - "tpm" > - "tee" > + - "caam" > If not specified then it defaults to iterating through > the trust source list starting with TPM and assigns the > first trust source as a backend which is initialized > diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst > index 99cf34d7c025..ed60c48cb692 100644 > --- a/Documentation/security/keys/trusted-encrypted.rst > +++ b/Documentation/security/keys/trusted-encrypted.rst > @@ -35,6 +35,13 @@ safe. > Rooted to Hardware Unique Key (HUK) which is generally burnt in on-chip > fuses and is accessible to TEE only. > > + (3) CAAM (Cryptographic Acceleration and Assurance Module: IP on NXP SoCs) > + > + When High Assurance Boot (HAB) is enabled and the CAAM is in secure > + mode, trust is rooted to the OTPMK, a never-disclosed 256-bit key > + randomly generated and fused into each SoC at manufacturing time. > + Otherwise, a common fixed test key is used instead. > + > * Execution isolation > > (1) TPM > @@ -46,6 +53,10 @@ safe. > Customizable set of operations running in isolated execution > environment verified via Secure/Trusted boot process. > > + (3) CAAM > + > + Fixed set of operations running in isolated execution environment. > + > * Optional binding to platform integrity state > > (1) TPM > @@ -63,6 +74,11 @@ safe. > Relies on Secure/Trusted boot process for platform integrity. It can > be extended with TEE based measured boot process. > > + (3) CAAM > + > + Relies on the High Assurance Boot (HAB) mechanism of NXP SoCs > + for platform integrity. > + > * Interfaces and APIs > > (1) TPM > @@ -74,10 +90,13 @@ safe. > TEEs have well-documented, standardized client interface and APIs. For > more details refer to ``Documentation/staging/tee.rst``. > > + (3) CAAM > + > + Interface is specific to silicon vendor. > > * Threat model > > - The strength and appropriateness of a particular TPM or TEE for a given > + The strength and appropriateness of a particular trust source for a given > purpose must be assessed when using them to protect security-relevant data. > > > @@ -104,6 +123,12 @@ selected trust source: > from platform specific hardware RNG or a software based Fortuna CSPRNG > which can be seeded via multiple entropy sources. > > + * CAAM: Kernel RNG > + > + The normal kernel random number generator is used. To seed it from the > + CAAM HWRNG, enable CRYPTO_DEV_FSL_CAAM_RNG_API and ensure the device > + is probed. > + > 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. > > @@ -192,6 +217,19 @@ Usage:: > specific to TEE device implementation. The key length for new keys is always > in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits). > > +Trusted Keys usage: CAAM > +------------------------ > + > +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 CAAM device implementation. The key length for new keys is always > +in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits). > + > Encrypted Keys usage > -------------------- > > diff --git a/MAINTAINERS b/MAINTAINERS > index 05fd080b82f3..f13382a14967 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -10647,6 +10647,15 @@ S: Supported > F: include/keys/trusted_tee.h > F: security/keys/trusted-keys/trusted_tee.c > > +KEYS-TRUSTED-CAAM > +M: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > +R: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx> > +L: linux-integrity@xxxxxxxxxxxxxxx > +L: keyrings@xxxxxxxxxxxxxxx > +S: Maintained > +F: include/keys/trusted_caam.h > +F: security/keys/trusted-keys/trusted_caam.c > + > KEYS/KEYRINGS > M: David Howells <dhowells@xxxxxxxxxx> > M: Jarkko Sakkinen <jarkko@xxxxxxxxxx> Documentation and MAINTAINERS updates must be separate patches. BR, Jarkko
