RE: [PATCH] crypto: caam - add a test for the RNG

[Gaurav Jain]

Reviewed-by: Gaurav Jain <gaurav.jain@xxxxxxx>

> -----Original Message-----
> From: Meenakshi Aggarwal <meenakshi.aggarwal@xxxxxxx>
> Sent: Monday, June 12, 2023 1:59 PM
> To: Horia Geanta <horia.geanta@xxxxxxx>; Varun Sethi <V.Sethi@xxxxxxx>;
> Pankaj Gupta <pankaj.gupta@xxxxxxx>; Gaurav Jain <gaurav.jain@xxxxxxx>;
> herbert@xxxxxxxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx; linux-
> crypto@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: Victoria Milhoan (b42089) <vicki.milhoan@xxxxxxxxxxxxx>; Dan Douglass
> <dan.douglass@xxxxxxx>; Vipul Kumar <vipul_kumar@xxxxxxxxxx>;
> Meenakshi Aggarwal <meenakshi.aggarwal@xxxxxxx>
> Subject: [PATCH] crypto: caam - add a test for the RNG
> 
> From: "Victoria Milhoan (b42089)" <vicki.milhoan@xxxxxxxxxxxxx>
> 
> CAAM includes a Random Number Generator.  This change adds a kernel
> configuration option to test the RNG's capabilities via the hw_random
> framework.
> 
> Signed-off-by: Victoria Milhoan <vicki.milhoan@xxxxxxxxxxxxx>
> Signed-off-by: Dan Douglass <dan.douglass@xxxxxxx>
> Signed-off-by: Vipul Kumar <vipul_kumar@xxxxxxxxxx>
> Signed-off-by: Horia Geantă <horia.geanta@xxxxxxx>
> Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@xxxxxxx>
> ---
>  drivers/crypto/caam/Kconfig   |  9 +++++++
>  drivers/crypto/caam/caamrng.c | 48
> +++++++++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig index
> ec6a9e6ad4d2..c631f99e415f 100644
> --- a/drivers/crypto/caam/Kconfig
> +++ b/drivers/crypto/caam/Kconfig
> @@ -162,6 +162,15 @@ config CRYPTO_DEV_FSL_CAAM_PRNG_API  config
> CRYPTO_DEV_FSL_CAAM_BLOB_GEN
>  	bool
> 
> +config CRYPTO_DEV_FSL_CAAM_RNG_TEST
> +	bool "Test caam rng"
> +	select CRYPTO_DEV_FSL_CAAM_RNG_API
> +	help
> +	  Selecting this will enable a self-test to run for the
> +	  caam RNG.
> +	  This test is several minutes long and executes
> +	  just before the RNG is registered with the hw_random API.
> +
>  endif # CRYPTO_DEV_FSL_CAAM_JR
> 
>  endif # CRYPTO_DEV_FSL_CAAM
> diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
> index 50eb55da45c2..b3d14a7f4dd1 100644
> --- a/drivers/crypto/caam/caamrng.c
> +++ b/drivers/crypto/caam/caamrng.c
> @@ -172,6 +172,50 @@ static void caam_cleanup(struct hwrng *rng)
>  	kfifo_free(&ctx->fifo);
>  }
> 
> +#ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_TEST
> +static inline void test_len(struct hwrng *rng, size_t len, bool wait) {
> +	u8 *buf;
> +	int read_len;
> +	struct caam_rng_ctx *ctx = to_caam_rng_ctx(rng);
> +	struct device *dev = ctx->ctrldev;
> +
> +	buf = kcalloc(CAAM_RNG_MAX_FIFO_STORE_SIZE, sizeof(u8),
> GFP_KERNEL);
> +
> +	while (len > 0) {
> +		read_len = rng->read(rng, buf, len, wait);
> +
> +		if (read_len < 0 || (read_len == 0 && wait)) {
> +			dev_err(dev, "RNG Read FAILED received %d bytes\n",
> +				read_len);
> +			kfree(buf);
> +			return;
> +		}
> +
> +		print_hex_dump_debug("random bytes@: ",
> +			DUMP_PREFIX_ADDRESS, 16, 4,
> +			buf, read_len, 1);
> +
> +		len = len - read_len;
> +	}
> +
> +	kfree(buf);
> +}
> +
> +static inline void test_mode_once(struct hwrng *rng, bool wait) {
> +	test_len(rng, 32, wait);
> +	test_len(rng, 64, wait);
> +	test_len(rng, 128, wait);
> +}
> +
> +static void self_test(struct hwrng *rng) {
> +	pr_info("Executing RNG SELF-TEST with wait\n");
> +	test_mode_once(rng, true);
> +}
> +#endif
> +
>  static int caam_init(struct hwrng *rng)  {
>  	struct caam_rng_ctx *ctx = to_caam_rng_ctx(rng); @@ -258,6 +302,10
> @@ int caam_rng_init(struct device *ctrldev)
>  		return ret;
>  	}
> 
> +#ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_TEST
> +	self_test(&ctx->rng);
> +#endif
> +
>  	devres_close_group(ctrldev, caam_rng_init);
>  	return 0;
>  }
> --
> 2.25.1