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| /optee_os/core/drivers/crypto/caam/ |
| H A D | caam_rng.c | 7a5015dd35b93a52fe7c7744aa2b9140a1d031de Wed Jun 28 13:07:27 UTC 2023 Rouven Czerwinski <r.czerwinski@pengutronix.de> drivers: caam: provide plat_rng_init if CFG_WITH_SOFTWARE_PRNG=y
With CFG_NXP_CAAM_RNG_DRV enabled, OP-TEE will use the CAAM to generate random numbers. Normal world access to the RNG is still possible as the CAAM is TrustZone aware and provides multiple separate job rings.
For complete isolation, however, access to CAAM reset and clocks need to be managed as well. This could be done in theory by restricting access to the reset and clock controller peripherals to the secure world and exporting limited access to some resources via SCMI. There is no such support yet for the i.MX and thus some setups may prefer to avoid using the CAAM in OP-TEE to stay safe from normal world inducing glitches.
These setups may still need random numbers in OP-TEE. Therefore, access so have them access the CAAM only once at startup to initialize OP-TEE's PRNG and defer subsequent use of the CAAM to the normal world, whenever CFG_WITH_SOFTWARE_PRNG=y.
Reviewed-by: Clement Faure <clement.faure@nxp.com> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
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| H A D | crypto.mk | 7a5015dd35b93a52fe7c7744aa2b9140a1d031de Wed Jun 28 13:07:27 UTC 2023 Rouven Czerwinski <r.czerwinski@pengutronix.de> drivers: caam: provide plat_rng_init if CFG_WITH_SOFTWARE_PRNG=y
With CFG_NXP_CAAM_RNG_DRV enabled, OP-TEE will use the CAAM to generate random numbers. Normal world access to the RNG is still possible as the CAAM is TrustZone aware and provides multiple separate job rings.
For complete isolation, however, access to CAAM reset and clocks need to be managed as well. This could be done in theory by restricting access to the reset and clock controller peripherals to the secure world and exporting limited access to some resources via SCMI. There is no such support yet for the i.MX and thus some setups may prefer to avoid using the CAAM in OP-TEE to stay safe from normal world inducing glitches.
These setups may still need random numbers in OP-TEE. Therefore, access so have them access the CAAM only once at startup to initialize OP-TEE's PRNG and defer subsequent use of the CAAM to the normal world, whenever CFG_WITH_SOFTWARE_PRNG=y.
Reviewed-by: Clement Faure <clement.faure@nxp.com> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
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