Re: [PATCH v2 04/10] soc: qcom: ice: support for hardware wrapped keys

[Neil Armstrong <neil.armstrong@linaro.org>]

Hi,

On 19/07/2023 19:04, Gaurav Kashyap wrote:
> Now that HWKM support is added to ICE, extend the ICE
> driver to support hardware wrapped keys programming coming
> in from the storage controllers (ufs and emmc). The patches that follow
> will add ufs and emmc support.
> 
> Derive software secret support is also added by forwarding the
> call the corresponding scm api.
> 
> Signed-off-by: Gaurav Kashyap <quic_gaurkash@quicinc.com>
> ---
>   drivers/soc/qcom/ice.c | 121 +++++++++++++++++++++++++++++++++++++----
>   include/soc/qcom/ice.h |   4 ++
>   2 files changed, 114 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/soc/qcom/ice.c b/drivers/soc/qcom/ice.c
> index 242306d13049..33f67fcfa1bc 100644
> --- a/drivers/soc/qcom/ice.c
> +++ b/drivers/soc/qcom/ice.c
> @@ -25,6 +25,8 @@
>   #define QCOM_ICE_REG_BIST_STATUS		0x0070
>   #define QCOM_ICE_REG_ADVANCED_CONTROL		0x1000
>   #define QCOM_ICE_REG_CONTROL			0x0
> +#define QCOM_ICE_LUT_KEYS_CRYPTOCFG_R16		0x4040
> +
>   /* QCOM ICE HWKM registers */
>   #define QCOM_ICE_REG_HWKM_TZ_KM_CTL		0x1000
>   #define QCOM_ICE_REG_HWKM_TZ_KM_STATUS		0x1004
> @@ -34,6 +36,7 @@
>   #define QCOM_ICE_REG_HWKM_BANK0_BBAC_3		0x500C
>   #define QCOM_ICE_REG_HWKM_BANK0_BBAC_4		0x5010
>   
> +/* QCOM ICE HWKM BIST vals */
>   #define QCOM_ICE_HWKM_BIST_DONE_V1_VAL		0x11
>   #define QCOM_ICE_HWKM_BIST_DONE_V2_VAL		0x287
>   
> @@ -44,6 +47,8 @@
>   #define QCOM_ICE_FORCE_HW_KEY0_SETTING_MASK	0x2
>   #define QCOM_ICE_FORCE_HW_KEY1_SETTING_MASK	0x4
>   
> +#define QCOM_ICE_LUT_KEYS_CRYPTOCFG_OFFSET	0x80
> +
>   #define QCOM_ICE_HWKM_REG_OFFSET	0x8000
>   #define HWKM_OFFSET(reg)		(reg + QCOM_ICE_HWKM_REG_OFFSET)
>   
> @@ -60,6 +65,17 @@ struct qcom_ice {
>   
>   	struct clk *core_clk;
>   	u8 hwkm_version;
> +	bool hwkm_init_complete;
> +};
> +
> +union crypto_cfg {
> +	__le32 regval;
> +	struct {
> +		u8 dusize;
> +		u8 capidx;
> +		u8 reserved;
> +		u8 cfge;
> +	};
>   };
>   
>   static bool qcom_ice_check_supported(struct qcom_ice *ice)
> @@ -218,6 +234,8 @@ static void qcom_ice_hwkm_init(struct qcom_ice *ice)
>   			HWKM_OFFSET(QCOM_ICE_REG_HWKM_BANK0_BBAC_3));
>   	qcom_ice_writel(ice, 0xFFFFFFFF,
>   			HWKM_OFFSET(QCOM_ICE_REG_HWKM_BANK0_BBAC_4));
> +
> +	ice->hwkm_init_complete = true;
>   }
>   
>   int qcom_ice_enable(struct qcom_ice *ice)
> @@ -263,6 +281,52 @@ int qcom_ice_suspend(struct qcom_ice *ice)
>   }
>   EXPORT_SYMBOL_GPL(qcom_ice_suspend);
>   
> +/*
> + * HW dictates the internal mapping between the ICE and HWKM slots,
> + * which are different for different versions, make the translation
> + * here.
> +*/
> +static int translate_hwkm_slot(struct qcom_ice *ice, int slot)
> +{
> +	return (ice->hwkm_version == 1) ?
> +	       (10 + slot * 2) : (slot * 2);
> +}
> +
> +static int qcom_ice_program_wrapped_key(struct qcom_ice *ice,
> +					const struct blk_crypto_key *key,
> +					u8 data_unit_size, int slot)
> +{
> +	int hwkm_slot;
> +	int err;
> +	union crypto_cfg cfg;
> +
> +	hwkm_slot = translate_hwkm_slot(ice, slot);
> +
> +	memset(&cfg, 0, sizeof(cfg));
> +	cfg.dusize = data_unit_size;
> +	cfg.capidx = QCOM_SCM_ICE_CIPHER_AES_256_XTS;
> +	cfg.cfge = 0x80;
> +
> +	/* Clear CFGE */
> +	qcom_ice_writel(ice, 0x0, QCOM_ICE_LUT_KEYS_CRYPTOCFG_R16 +
> +				  QCOM_ICE_LUT_KEYS_CRYPTOCFG_OFFSET * slot);
> +
> +	/* Call trustzone to program the wrapped key using hwkm */
> +	err = qcom_scm_ice_set_key(hwkm_slot, key->raw, key->size,
> +				   QCOM_SCM_ICE_CIPHER_AES_256_XTS, data_unit_size);
> +	if (err) {
> +		pr_err("%s:SCM call Error: 0x%x slot %d\n", __func__, err,
> +		       slot);
> +		return err;
> +	}
> +
> +	/* Enable CFGE after programming key */
> +	qcom_ice_writel(ice, cfg.regval, QCOM_ICE_LUT_KEYS_CRYPTOCFG_R16 +
> +					 QCOM_ICE_LUT_KEYS_CRYPTOCFG_OFFSET * slot);
> +
> +	return err;
> +}
> +
>   int qcom_ice_program_key(struct qcom_ice *ice,
>   			 u8 algorithm_id, u8 key_size,
>   			 const struct blk_crypto_key *bkey,
> @@ -278,24 +342,36 @@ int qcom_ice_program_key(struct qcom_ice *ice,
>   
>   	/* Only AES-256-XTS has been tested so far. */
>   	if (algorithm_id != QCOM_ICE_CRYPTO_ALG_AES_XTS ||
> -	    key_size != QCOM_ICE_CRYPTO_KEY_SIZE_256) {
> +	    key_size != QCOM_ICE_CRYPTO_KEY_SIZE_256 ||
> +	    key_size != QCOM_ICE_CRYPTO_KEY_SIZE_WRAPPED) {

This should be:
	if (algorithm_id != QCOM_ICE_CRYPTO_ALG_AES_XTS ||
	    (key_size != QCOM_ICE_CRYPTO_KEY_SIZE_256 &&
	     key_size != QCOM_ICE_CRYPTO_KEY_SIZE_WRAPPED)) {

Otherwise it would fail on any key_size value.

Neil

>   		dev_err_ratelimited(dev,
>   				    "Unhandled crypto capability; algorithm_id=%d, key_size=%d\n",
>   				    algorithm_id, key_size);
>   		return -EINVAL;
>   	}
>   
> -	memcpy(key.bytes, bkey->raw, AES_256_XTS_KEY_SIZE);
> -
> -	/* The SCM call requires that the key words are encoded in big endian */
> -	for (i = 0; i < ARRAY_SIZE(key.words); i++)
> -		__cpu_to_be32s(&key.words[i]);
> +	if (bkey->crypto_cfg.key_type == BLK_CRYPTO_KEY_TYPE_HW_WRAPPED) {
> +		if (!ice->hwkm_version)
> +			return -EINVAL;
> +		err = qcom_ice_program_wrapped_key(ice, bkey, slot,
> +						   data_unit_size);
> +	} else {
> +		if (bkey->size != QCOM_ICE_CRYPTO_KEY_SIZE_256)
> +			dev_err_ratelimited(dev,
> +				    "Incorrect key size; bkey->size=%d\n",
> +				    algorithm_id);
> +		return -EINVAL;
> +		memcpy(key.bytes, bkey->raw, AES_256_XTS_KEY_SIZE);
>   
> -	err = qcom_scm_ice_set_key(slot, key.bytes, AES_256_XTS_KEY_SIZE,
> -				   QCOM_SCM_ICE_CIPHER_AES_256_XTS,
> -				   data_unit_size);
> +		/* The SCM call requires that the key words are encoded in big endian */
> +		for (i = 0; i < ARRAY_SIZE(key.words); i++)
> +			__cpu_to_be32s(&key.words[i]);
>   
> -	memzero_explicit(&key, sizeof(key));
> +		err = qcom_scm_ice_set_key(slot, key.bytes, AES_256_XTS_KEY_SIZE,
> +					   QCOM_SCM_ICE_CIPHER_AES_256_XTS,
> +					   data_unit_size);
> +		memzero_explicit(&key, sizeof(key));
> +	}
>   
>   	return err;
>   }
> @@ -303,7 +379,21 @@ EXPORT_SYMBOL_GPL(qcom_ice_program_key);
>   
>   int qcom_ice_evict_key(struct qcom_ice *ice, int slot)
>   {
> -	return qcom_scm_ice_invalidate_key(slot);
> +	int hwkm_slot = slot;
> +
> +	if (ice->hwkm_version) {
> +		hwkm_slot = translate_hwkm_slot(ice, slot);
> +	/*
> +	 * Ignore calls to evict key when HWKM is supported and hwkm init
> +	 * is not yet done. This is to avoid the clearing all slots call
> +	 * during a storage reset when ICE is still in legacy mode. HWKM slave
> +	 * in ICE takes care of zeroing out the keytable on reset.
> +	 */
> +		if (!ice->hwkm_init_complete)
> +			return 0;
> +	}
> +
> +	return qcom_scm_ice_invalidate_key(hwkm_slot);
>   }
>   EXPORT_SYMBOL_GPL(qcom_ice_evict_key);
>   
> @@ -313,6 +403,15 @@ bool qcom_ice_hwkm_supported(struct qcom_ice *ice)
>   }
>   EXPORT_SYMBOL_GPL(qcom_ice_hwkm_supported);
>   
> +int qcom_ice_derive_sw_secret(struct qcom_ice *ice, const u8 wrapped_key[],
> +			      unsigned int wrapped_key_size,
> +			      u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE])
> +{
> +	return qcom_scm_derive_sw_secret(wrapped_key, wrapped_key_size,
> +					 sw_secret, BLK_CRYPTO_SW_SECRET_SIZE);
> +}
> +EXPORT_SYMBOL_GPL(qcom_ice_derive_sw_secret);
> +
>   static struct qcom_ice *qcom_ice_create(struct device *dev,
>   					void __iomem *base)
>   {
> diff --git a/include/soc/qcom/ice.h b/include/soc/qcom/ice.h
> index 1f52e82e3e1c..22ab8d1a56de 100644
> --- a/include/soc/qcom/ice.h
> +++ b/include/soc/qcom/ice.h
> @@ -17,6 +17,7 @@ enum qcom_ice_crypto_key_size {
>   	QCOM_ICE_CRYPTO_KEY_SIZE_192		= 0x2,
>   	QCOM_ICE_CRYPTO_KEY_SIZE_256		= 0x3,
>   	QCOM_ICE_CRYPTO_KEY_SIZE_512		= 0x4,
> +	QCOM_ICE_CRYPTO_KEY_SIZE_WRAPPED	= 0x5,
>   };
>   
>   enum qcom_ice_crypto_alg {
> @@ -35,5 +36,8 @@ int qcom_ice_program_key(struct qcom_ice *ice,
>   			 u8 data_unit_size, int slot);
>   int qcom_ice_evict_key(struct qcom_ice *ice, int slot);
>   bool qcom_ice_hwkm_supported(struct qcom_ice *ice);
> +int qcom_ice_derive_sw_secret(struct qcom_ice *ice, const u8 wrapped_key[],
> +			      unsigned int wrapped_key_size,
> +			      u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]);
>   struct qcom_ice *of_qcom_ice_get(struct device *dev);
>   #endif /* __QCOM_ICE_H__ */