On Thu, Apr 28, 2022 at 04:01:44PM +0200, Ahmad Fatoum wrote: > Update documentation for trusted key use with the Cryptographic > Acceleration and Assurance Module (CAAM), an IP on NXP SoCs. > > Reviewed-by: Pankaj Gupta <pankaj.gupta@xxxxxxx> > Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > --- > v7 -> v8: > - add Pankaj's Reviewed-by > v6 -> v7: > - docs update split off as new Patch (Jarkko) > - fixed typo in "Trusted Keys usage: CAAM" section > > 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: Pankaj Gupta <pankaj.gupta@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 > --- > .../security/keys/trusted-encrypted.rst | 40 ++++++++++++++++++- > 1 file changed, 39 insertions(+), 1 deletion(-) > > diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst > index 2fe6fd1a2bbd..0bfb4c339748 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. > > @@ -193,6 +218,19 @@ 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 a > +CAAM-specific format. The key length for new keys is always in bytes. > +Trusted Keys can be 32 - 128 bytes (256 - 1024 bits). > + > Encrypted Keys usage > -------------------- > > -- > 2.30.2 > Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> BR, Jarkko
