diff mbox series

[1/3] rng: add OP-TEE based Random Number Generator

Message ID 20220322150558.1.I2d5fc62b65a61d4e11ce442f3b5572ec03f39cf6@changeid
State Superseded
Delegated to: Tom Rini
Headers show
Series [1/3] rng: add OP-TEE based Random Number Generator | expand

Commit Message

Patrick DELAUNAY March 22, 2022, 2:06 p.m. UTC 
Add driver for OP-TEE based Random Number Generator on ARM SoCs
where hardware entropy sources are not accessible to normal world
and the RNG service is provided by a HWRNG Trusted Application (TA).

This driver is based on the linux driver: char/hw_random/optee-rng.c

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
---

 MAINTAINERS             |   1 +
 drivers/rng/Kconfig     |   8 +++
 drivers/rng/Makefile    |   1 +
 drivers/rng/optee_rng.c | 156 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 166 insertions(+)
 create mode 100644 drivers/rng/optee_rng.c

Comments

Heinrich Schuchardt March 22, 2022, 2:38 p.m. UTC | #1 
On 3/22/22 15:06, Patrick Delaunay wrote:
> Add driver for OP-TEE based Random Number Generator on ARM SoCs
> where hardware entropy sources are not accessible to normal world
> and the RNG service is provided by a HWRNG Trusted Application (TA).
>
> This driver is based on the linux driver: char/hw_random/optee-rng.c
>
> Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
> ---
>
>   MAINTAINERS             |   1 +
>   drivers/rng/Kconfig     |   8 +++
>   drivers/rng/Makefile    |   1 +
>   drivers/rng/optee_rng.c | 156 ++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 166 insertions(+)
>   create mode 100644 drivers/rng/optee_rng.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f25ca7cd00..3356c65dd0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -481,6 +481,7 @@ F:	drivers/power/regulator/stpmic1.c
>   F:	drivers/ram/stm32mp1/
>   F:	drivers/remoteproc/stm32_copro.c
>   F:	drivers/reset/stm32-reset.c
> +F:	drivers/rng/optee_rng.c
>   F:	drivers/rng/stm32mp1_rng.c
>   F:	drivers/rtc/stm32_rtc.c
>   F:	drivers/serial/serial_stm32.*
> diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
> index b1c5ab93d1..a02c585f61 100644
> --- a/drivers/rng/Kconfig
> +++ b/drivers/rng/Kconfig
> @@ -31,6 +31,14 @@ config RNG_MSM
>   	  This driver provides support for the Random Number
>   	  Generator hardware found on Qualcomm SoCs.
>
> +config RNG_OPTEE
> +	bool "OP-TEE based Random Number Generator support"
> +	depends on DM_RNG && OPTEE
> +	help
> +	  This driver provides support for OP-TEE based Random Number
> +	  Generator on ARM SoCs where hardware entropy sources are not
> +	  accessible to normal world.


https://optee.readthedocs.io/en/latest/architecture/porting_guidelines.html
has:

"By default OP-TEE is configured with a software PRNG. The entropy is
added to software PRNG at various places, but unfortunately it is still
quite easy to predict the data added as entropy. As a consequence,
unless the RNG is based on hardware the generated random will be quite
weak."

Having a similiar warning in the long text for the CONFIG_RNG_OPTEE
symbol would be helpful.

> +
>   config RNG_STM32MP1
>   	bool "Enable random number generator for STM32MP1"
>   	depends on ARCH_STM32MP
> diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
> index 39f7ee3f03..435b3b965a 100644
> --- a/drivers/rng/Makefile
> +++ b/drivers/rng/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_DM_RNG) += rng-uclass.o
>   obj-$(CONFIG_RNG_MESON) += meson-rng.o
>   obj-$(CONFIG_RNG_SANDBOX) += sandbox_rng.o
>   obj-$(CONFIG_RNG_MSM) += msm_rng.o
> +obj-$(CONFIG_RNG_OPTEE) += optee_rng.o
>   obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
>   obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o
>   obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
> diff --git a/drivers/rng/optee_rng.c b/drivers/rng/optee_rng.c
> new file mode 100644
> index 0000000000..a0833d0862
> --- /dev/null
> +++ b/drivers/rng/optee_rng.c
> @@ -0,0 +1,156 @@
> +// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
> +/*
> + * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
> + */
> +#define LOG_CATEGORY UCLASS_RNG
> +
> +#include <common.h>
> +
> +#include <rng.h>
> +#include <tee.h>
> +#include <dm/device.h>
> +#include <dm/device_compat.h>
> +#include <linux/sizes.h>
> +
> +#define TEE_ERROR_HEALTH_TEST_FAIL	0x00000001
> +
> +/*
> + * TA_CMD_GET_ENTROPY - Get Entropy from RNG
> + *
> + * param[0] (inout memref) - Entropy buffer memory reference
> + * param[1] unused
> + * param[2] unused
> + * param[3] unused
> + *
> + * Result:
> + * TEE_SUCCESS - Invoke command success
> + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
> + * TEE_ERROR_NOT_SUPPORTED - Requested entropy size greater than size of pool
> + * TEE_ERROR_HEALTH_TEST_FAIL - Continuous health testing failed
> + */
> +#define TA_CMD_GET_ENTROPY		0x0
> +
> +#define MAX_ENTROPY_REQ_SZ		SZ_4K
> +
> +#define TA_HWRNG_UUID { 0xab7a617c, 0xb8e7, 0x4d8f, \
> +			{ 0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64 } }
> +
> +/**
> + * struct optee_rng_priv - OP-TEE Random Number Generator private data
> + * @session_id:		RNG TA session identifier.
> + */
> +struct optee_rng_priv {
> +	u32 session_id;
> +};
> +

Please, provide as Sphinx style function description.

> +static int get_optee_rng_data(struct udevice *dev,
> +			      struct tee_shm *entropy_shm_pool,
> +			      void *buf, size_t *size)
> +{
> +	struct optee_rng_priv *priv = dev_get_priv(dev);
> +	int ret = 0;
> +	struct tee_invoke_arg arg;

Wouldn't it be preferable to use

struct tee_invoke_arg arg = { 0 }; ?

This way the compiler can optimize the initialization and set all 0
initialized variables with a single memset() call.

Best regards

Heinrich

> +	struct tee_param param;
> +
> +	memset(&arg, 0, sizeof(arg));
> +	memset(&param, 0, sizeof(param));
> +
> +	/* Invoke TA_CMD_GET_ENTROPY function of Trusted App */
> +	arg.func = TA_CMD_GET_ENTROPY;
> +	arg.session = priv->session_id;
> +
> +	/* Fill invoke cmd params */
> +	param.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
> +	param.u.memref.shm = entropy_shm_pool;
> +	param.u.memref.size = *size;
> +
> +	ret = tee_invoke_func(dev->parent, &arg, 1, &param);
> +	if (ret || arg.ret) {
> +		if (!ret)
> +			ret = -EPROTO;
> +		dev_err(dev, "TA_CMD_GET_ENTROPY invoke err: %d 0x%x\n", ret, arg.ret);
> +		*size = 0;
> +
> +		return ret;
> +	}
> +
> +	memcpy(buf, param.u.memref.shm->addr, param.u.memref.size);
> +	*size = param.u.memref.size;
> +
> +	return 0;
> +}
> +
> +static int optee_rng_read(struct udevice *dev, void *buf, size_t len)
> +{
> +	size_t read = 0, rng_size = 0;
> +	struct tee_shm *entropy_shm_pool;
> +	u8 *data = buf;
> +	int ret;
> +
> +	ret = tee_shm_alloc(dev->parent, MAX_ENTROPY_REQ_SZ, 0, &entropy_shm_pool);
> +	if (ret) {
> +		dev_err(dev, "tee_shm_alloc failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	while (read < len) {
> +		rng_size = min(len - read, (size_t)MAX_ENTROPY_REQ_SZ);
> +		ret = get_optee_rng_data(dev, entropy_shm_pool, data, &rng_size);
> +		if (ret)
> +			goto shm_free;
> +		data += rng_size;
> +		read += rng_size;
> +	}
> +
> +shm_free:
> +	tee_shm_free(entropy_shm_pool);
> +
> +	return ret;
> +}
> +
> +static int optee_rng_probe(struct udevice *dev)
> +{
> +	const struct tee_optee_ta_uuid uuid = TA_HWRNG_UUID;
> +	struct optee_rng_priv *priv = dev_get_priv(dev);
> +	struct tee_open_session_arg sess_arg;
> +	int ret;
> +
> +	memset(&sess_arg, 0, sizeof(sess_arg));
> +
> +	/* Open session with hwrng Trusted App */
> +	tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
> +	sess_arg.clnt_login = TEE_LOGIN_PUBLIC;
> +
> +	ret = tee_open_session(dev->parent, &sess_arg, 0, NULL);
> +	if (ret || sess_arg.ret) {
> +		if (!ret)
> +			ret = -EIO;
> +		dev_err(dev, "can't open session: %d 0x%x\n", ret, sess_arg.ret);
> +		return ret;
> +	}
> +	priv->session_id = sess_arg.session;
> +
> +	return 0;
> +}
> +
> +static int optee_rng_remove(struct udevice *dev)
> +{
> +	struct optee_rng_priv *priv = dev_get_priv(dev);
> +
> +	tee_close_session(dev->parent, priv->session_id);
> +
> +	return 0;
> +}
> +
> +static const struct dm_rng_ops optee_rng_ops = {
> +	.read = optee_rng_read,
> +};
> +
> +U_BOOT_DRIVER(optee_rng) = {
> +	.name = "optee-rng",
> +	.id = UCLASS_RNG,
> +	.ops = &optee_rng_ops,
> +	.probe = optee_rng_probe,
> +	.remove = optee_rng_remove,
> +	.priv_auto = sizeof(struct optee_rng_priv),
> +};
Patrick DELAUNAY March 24, 2022, 11:03 a.m. UTC | #2 
Hi,

On 3/22/22 15:38, Heinrich Schuchardt wrote:
> On 3/22/22 15:06, Patrick Delaunay wrote:
>> Add driver for OP-TEE based Random Number Generator on ARM SoCs
>> where hardware entropy sources are not accessible to normal world
>> and the RNG service is provided by a HWRNG Trusted Application (TA).
>>
>> This driver is based on the linux driver: char/hw_random/optee-rng.c
>>
>> Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
>> ---
>>
>>   MAINTAINERS             |   1 +
>>   drivers/rng/Kconfig     |   8 +++
>>   drivers/rng/Makefile    |   1 +
>>   drivers/rng/optee_rng.c | 156 ++++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 166 insertions(+)
>>   create mode 100644 drivers/rng/optee_rng.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index f25ca7cd00..3356c65dd0 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -481,6 +481,7 @@ F:    drivers/power/regulator/stpmic1.c
>>   F:    drivers/ram/stm32mp1/
>>   F:    drivers/remoteproc/stm32_copro.c
>>   F:    drivers/reset/stm32-reset.c
>> +F:    drivers/rng/optee_rng.c
>>   F:    drivers/rng/stm32mp1_rng.c
>>   F:    drivers/rtc/stm32_rtc.c
>>   F:    drivers/serial/serial_stm32.*
>> diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
>> index b1c5ab93d1..a02c585f61 100644
>> --- a/drivers/rng/Kconfig
>> +++ b/drivers/rng/Kconfig
>> @@ -31,6 +31,14 @@ config RNG_MSM
>>         This driver provides support for the Random Number
>>         Generator hardware found on Qualcomm SoCs.
>>
>> +config RNG_OPTEE
>> +    bool "OP-TEE based Random Number Generator support"
>> +    depends on DM_RNG && OPTEE
>> +    help
>> +      This driver provides support for OP-TEE based Random Number
>> +      Generator on ARM SoCs where hardware entropy sources are not
>> +      accessible to normal world.
>
>
> https://optee.readthedocs.io/en/latest/architecture/porting_guidelines.html 
>
> has:
>
> "By default OP-TEE is configured with a software PRNG. The entropy is
> added to software PRNG at various places, but unfortunately it is still
> quite easy to predict the data added as entropy. As a consequence,
> unless the RNG is based on hardware the generated random will be quite
> weak."
>
> Having a similiar warning in the long text for the CONFIG_RNG_OPTEE
> symbol would be helpful.
>

I propose something as :


+config RNG_OPTEE
+    bool "OP-TEE based Random Number Generator support"
+    depends on DM_RNG && OPTEE
+    help
+      This driver provides support for OP-TEE based Random Number
+      Generator on ARM SoCs where hardware entropy sources are not
+      accessible to normal world but reserved and used by the OP-TEE

+      to avoid weakness of the software PRNG.


>> +
>>   config RNG_STM32MP1
>>       bool "Enable random number generator for STM32MP1"
>>       depends on ARCH_STM32MP
>> diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
>> index 39f7ee3f03..435b3b965a 100644
>> --- a/drivers/rng/Makefile
>> +++ b/drivers/rng/Makefile
>> @@ -7,6 +7,7 @@ obj-$(CONFIG_DM_RNG) += rng-uclass.o
>>   obj-$(CONFIG_RNG_MESON) += meson-rng.o
>>   obj-$(CONFIG_RNG_SANDBOX) += sandbox_rng.o
>>   obj-$(CONFIG_RNG_MSM) += msm_rng.o
>> +obj-$(CONFIG_RNG_OPTEE) += optee_rng.o
>>   obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
>>   obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o
>>   obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
>> diff --git a/drivers/rng/optee_rng.c b/drivers/rng/optee_rng.c
>> new file mode 100644
>> index 0000000000..a0833d0862
>> --- /dev/null
>> +++ b/drivers/rng/optee_rng.c
>> @@ -0,0 +1,156 @@
>> +// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
>> +/*
>> + * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
>> + */
>> +#define LOG_CATEGORY UCLASS_RNG
>> +
>> +#include <common.h>
>> +
>> +#include <rng.h>
>> +#include <tee.h>
>> +#include <dm/device.h>
>> +#include <dm/device_compat.h>
>> +#include <linux/sizes.h>
>> +
>> +#define TEE_ERROR_HEALTH_TEST_FAIL    0x00000001
>> +
>> +/*
>> + * TA_CMD_GET_ENTROPY - Get Entropy from RNG
>> + *
>> + * param[0] (inout memref) - Entropy buffer memory reference
>> + * param[1] unused
>> + * param[2] unused
>> + * param[3] unused
>> + *
>> + * Result:
>> + * TEE_SUCCESS - Invoke command success
>> + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
>> + * TEE_ERROR_NOT_SUPPORTED - Requested entropy size greater than 
>> size of pool
>> + * TEE_ERROR_HEALTH_TEST_FAIL - Continuous health testing failed
>> + */
>> +#define TA_CMD_GET_ENTROPY        0x0
>> +
>> +#define MAX_ENTROPY_REQ_SZ        SZ_4K
>> +
>> +#define TA_HWRNG_UUID { 0xab7a617c, 0xb8e7, 0x4d8f, \
>> +            { 0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64 } }
>> +
>> +/**
>> + * struct optee_rng_priv - OP-TEE Random Number Generator private data
>> + * @session_id:        RNG TA session identifier.
>> + */
>> +struct optee_rng_priv {
>> +    u32 session_id;
>> +};
>> +
>
> Please, provide as Sphinx style function description.
>

OK


>> +static int get_optee_rng_data(struct udevice *dev,
>> +                  struct tee_shm *entropy_shm_pool,
>> +                  void *buf, size_t *size)
>> +{
>> +    struct optee_rng_priv *priv = dev_get_priv(dev);
>> +    int ret = 0;
>> +    struct tee_invoke_arg arg;
>
> Wouldn't it be preferable to use
>
> struct tee_invoke_arg arg = { 0 }; ?
>
> This way the compiler can optimize the initialization and set all 0
> initialized variables with a single memset() call.
>

I wasn't sure of the portability for struct zero-initialisation.

But I will change it in V2.


> Best regards
>
> Heinrich
>
>> +    struct tee_param param;
>> +
>> +    memset(&arg, 0, sizeof(arg));
>> +    memset(&param, 0, sizeof(param));
>> +
>> +    /* Invoke TA_CMD_GET_ENTROPY function of Trusted App */
>> +    arg.func = TA_CMD_GET_ENTROPY;
>> +    arg.session = priv->session_id;
>> +
>> +    /* Fill invoke cmd params */
>> +    param.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
>> +    param.u.memref.shm = entropy_shm_pool;
>> +    param.u.memref.size = *size;
>> +
>> +    ret = tee_invoke_func(dev->parent, &arg, 1, &param);
>> +    if (ret || arg.ret) {
>> +        if (!ret)
>> +            ret = -EPROTO;
>> +        dev_err(dev, "TA_CMD_GET_ENTROPY invoke err: %d 0x%x\n", 
>> ret, arg.ret);
>> +        *size = 0;
>> +
>> +        return ret;
>> +    }
>> +
>> +    memcpy(buf, param.u.memref.shm->addr, param.u.memref.size);
>> +    *size = param.u.memref.size;
>> +
>> +    return 0;
>> +}
>> + 


(...)

Regards


Patrick
Heinrich Schuchardt March 24, 2022, 12:06 p.m. UTC | #3 
On 3/24/22 12:03, Patrick DELAUNAY wrote:
> Hi,
>
> On 3/22/22 15:38, Heinrich Schuchardt wrote:
>> On 3/22/22 15:06, Patrick Delaunay wrote:
>>> Add driver for OP-TEE based Random Number Generator on ARM SoCs
>>> where hardware entropy sources are not accessible to normal world
>>> and the RNG service is provided by a HWRNG Trusted Application (TA).
>>>
>>> This driver is based on the linux driver: char/hw_random/optee-rng.c
>>>
>>> Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
>>> ---
>>>
>>>   MAINTAINERS             |   1 +
>>>   drivers/rng/Kconfig     |   8 +++
>>>   drivers/rng/Makefile    |   1 +
>>>   drivers/rng/optee_rng.c | 156 ++++++++++++++++++++++++++++++++++++++++
>>>   4 files changed, 166 insertions(+)
>>>   create mode 100644 drivers/rng/optee_rng.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index f25ca7cd00..3356c65dd0 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -481,6 +481,7 @@ F:    drivers/power/regulator/stpmic1.c
>>>   F:    drivers/ram/stm32mp1/
>>>   F:    drivers/remoteproc/stm32_copro.c
>>>   F:    drivers/reset/stm32-reset.c
>>> +F:    drivers/rng/optee_rng.c
>>>   F:    drivers/rng/stm32mp1_rng.c
>>>   F:    drivers/rtc/stm32_rtc.c
>>>   F:    drivers/serial/serial_stm32.*
>>> diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
>>> index b1c5ab93d1..a02c585f61 100644
>>> --- a/drivers/rng/Kconfig
>>> +++ b/drivers/rng/Kconfig
>>> @@ -31,6 +31,14 @@ config RNG_MSM
>>>         This driver provides support for the Random Number
>>>         Generator hardware found on Qualcomm SoCs.
>>>
>>> +config RNG_OPTEE
>>> +    bool "OP-TEE based Random Number Generator support"
>>> +    depends on DM_RNG && OPTEE
>>> +    help
>>> +      This driver provides support for OP-TEE based Random Number
>>> +      Generator on ARM SoCs where hardware entropy sources are not
>>> +      accessible to normal world.
>>
>>
>> https://optee.readthedocs.io/en/latest/architecture/porting_guidelines.html
>>
>> has:
>>
>> "By default OP-TEE is configured with a software PRNG. The entropy is
>> added to software PRNG at various places, but unfortunately it is still
>> quite easy to predict the data added as entropy. As a consequence,
>> unless the RNG is based on hardware the generated random will be quite
>> weak."
>>
>> Having a similiar warning in the long text for the CONFIG_RNG_OPTEE
>> symbol would be helpful.
>>
>
> I propose something as :
>
>
> +config RNG_OPTEE
> +    bool "OP-TEE based Random Number Generator support"
> +    depends on DM_RNG && OPTEE
> +    help
> +      This driver provides support for OP-TEE based Random Number

%s/for/for the/

> +      Generator on ARM SoCs where hardware entropy sources are not
> +      accessible to normal world but reserved and used by the OP-TEE
>

%s/\n//

> +      to avoid weakness of the software PRNG.

%s/avoid weakness of the/avoid the weakness of a/

Looks ok to me.

Best regards

Heinrich

>
>
>>> +
>>>   config RNG_STM32MP1
>>>       bool "Enable random number generator for STM32MP1"
>>>       depends on ARCH_STM32MP
>>> diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
>>> index 39f7ee3f03..435b3b965a 100644
>>> --- a/drivers/rng/Makefile
>>> +++ b/drivers/rng/Makefile
>>> @@ -7,6 +7,7 @@ obj-$(CONFIG_DM_RNG) += rng-uclass.o
>>>   obj-$(CONFIG_RNG_MESON) += meson-rng.o
>>>   obj-$(CONFIG_RNG_SANDBOX) += sandbox_rng.o
>>>   obj-$(CONFIG_RNG_MSM) += msm_rng.o
>>> +obj-$(CONFIG_RNG_OPTEE) += optee_rng.o
>>>   obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
>>>   obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o
>>>   obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
>>> diff --git a/drivers/rng/optee_rng.c b/drivers/rng/optee_rng.c
>>> new file mode 100644
>>> index 0000000000..a0833d0862
>>> --- /dev/null
>>> +++ b/drivers/rng/optee_rng.c
>>> @@ -0,0 +1,156 @@
>>> +// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
>>> +/*
>>> + * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
>>> + */
>>> +#define LOG_CATEGORY UCLASS_RNG
>>> +
>>> +#include <common.h>
>>> +
>>> +#include <rng.h>
>>> +#include <tee.h>
>>> +#include <dm/device.h>
>>> +#include <dm/device_compat.h>
>>> +#include <linux/sizes.h>
>>> +
>>> +#define TEE_ERROR_HEALTH_TEST_FAIL    0x00000001
>>> +
>>> +/*
>>> + * TA_CMD_GET_ENTROPY - Get Entropy from RNG
>>> + *
>>> + * param[0] (inout memref) - Entropy buffer memory reference
>>> + * param[1] unused
>>> + * param[2] unused
>>> + * param[3] unused
>>> + *
>>> + * Result:
>>> + * TEE_SUCCESS - Invoke command success
>>> + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
>>> + * TEE_ERROR_NOT_SUPPORTED - Requested entropy size greater than
>>> size of pool
>>> + * TEE_ERROR_HEALTH_TEST_FAIL - Continuous health testing failed
>>> + */
>>> +#define TA_CMD_GET_ENTROPY        0x0
>>> +
>>> +#define MAX_ENTROPY_REQ_SZ        SZ_4K
>>> +
>>> +#define TA_HWRNG_UUID { 0xab7a617c, 0xb8e7, 0x4d8f, \
>>> +            { 0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64 } }
>>> +
>>> +/**
>>> + * struct optee_rng_priv - OP-TEE Random Number Generator private data
>>> + * @session_id:        RNG TA session identifier.
>>> + */
>>> +struct optee_rng_priv {
>>> +    u32 session_id;
>>> +};
>>> +
>>
>> Please, provide as Sphinx style function description.
>>
>
> OK
>
>
>>> +static int get_optee_rng_data(struct udevice *dev,
>>> +                  struct tee_shm *entropy_shm_pool,
>>> +                  void *buf, size_t *size)
>>> +{
>>> +    struct optee_rng_priv *priv = dev_get_priv(dev);
>>> +    int ret = 0;
>>> +    struct tee_invoke_arg arg;
>>
>> Wouldn't it be preferable to use
>>
>> struct tee_invoke_arg arg = { 0 }; ?
>>
>> This way the compiler can optimize the initialization and set all 0
>> initialized variables with a single memset() call.
>>
>
> I wasn't sure of the portability for struct zero-initialisation.
>
> But I will change it in V2.
>
>
>> Best regards
>>
>> Heinrich
>>
>>> +    struct tee_param param;
>>> +
>>> +    memset(&arg, 0, sizeof(arg));
>>> +    memset(&param, 0, sizeof(param));
>>> +
>>> +    /* Invoke TA_CMD_GET_ENTROPY function of Trusted App */
>>> +    arg.func = TA_CMD_GET_ENTROPY;
>>> +    arg.session = priv->session_id;
>>> +
>>> +    /* Fill invoke cmd params */
>>> +    param.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
>>> +    param.u.memref.shm = entropy_shm_pool;
>>> +    param.u.memref.size = *size;
>>> +
>>> +    ret = tee_invoke_func(dev->parent, &arg, 1, &param);
>>> +    if (ret || arg.ret) {
>>> +        if (!ret)
>>> +            ret = -EPROTO;
>>> +        dev_err(dev, "TA_CMD_GET_ENTROPY invoke err: %d 0x%x\n",
>>> ret, arg.ret);
>>> +        *size = 0;
>>> +
>>> +        return ret;
>>> +    }
>>> +
>>> +    memcpy(buf, param.u.memref.shm->addr, param.u.memref.size);
>>> +    *size = param.u.memref.size;
>>> +
>>> +    return 0;
>>> +}
>>> +
>
>
> (...)
>
> Regards
>
>
> Patrick
>
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index f25ca7cd00..3356c65dd0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -481,6 +481,7 @@  F:	drivers/power/regulator/stpmic1.c
 F:	drivers/ram/stm32mp1/
 F:	drivers/remoteproc/stm32_copro.c
 F:	drivers/reset/stm32-reset.c
+F:	drivers/rng/optee_rng.c
 F:	drivers/rng/stm32mp1_rng.c
 F:	drivers/rtc/stm32_rtc.c
 F:	drivers/serial/serial_stm32.*
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
index b1c5ab93d1..a02c585f61 100644
--- a/drivers/rng/Kconfig
+++ b/drivers/rng/Kconfig
@@ -31,6 +31,14 @@  config RNG_MSM
 	  This driver provides support for the Random Number
 	  Generator hardware found on Qualcomm SoCs.
 
+config RNG_OPTEE
+	bool "OP-TEE based Random Number Generator support"
+	depends on DM_RNG && OPTEE
+	help
+	  This driver provides support for OP-TEE based Random Number
+	  Generator on ARM SoCs where hardware entropy sources are not
+	  accessible to normal world.
+
 config RNG_STM32MP1
 	bool "Enable random number generator for STM32MP1"
 	depends on ARCH_STM32MP
diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
index 39f7ee3f03..435b3b965a 100644
--- a/drivers/rng/Makefile
+++ b/drivers/rng/Makefile
@@ -7,6 +7,7 @@  obj-$(CONFIG_DM_RNG) += rng-uclass.o
 obj-$(CONFIG_RNG_MESON) += meson-rng.o
 obj-$(CONFIG_RNG_SANDBOX) += sandbox_rng.o
 obj-$(CONFIG_RNG_MSM) += msm_rng.o
+obj-$(CONFIG_RNG_OPTEE) += optee_rng.o
 obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
 obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o
 obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
diff --git a/drivers/rng/optee_rng.c b/drivers/rng/optee_rng.c
new file mode 100644
index 0000000000..a0833d0862
--- /dev/null
+++ b/drivers/rng/optee_rng.c
@@ -0,0 +1,156 @@ 
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+/*
+ * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
+ */
+#define LOG_CATEGORY UCLASS_RNG
+
+#include <common.h>
+
+#include <rng.h>
+#include <tee.h>
+#include <dm/device.h>
+#include <dm/device_compat.h>
+#include <linux/sizes.h>
+
+#define TEE_ERROR_HEALTH_TEST_FAIL	0x00000001
+
+/*
+ * TA_CMD_GET_ENTROPY - Get Entropy from RNG
+ *
+ * param[0] (inout memref) - Entropy buffer memory reference
+ * param[1] unused
+ * param[2] unused
+ * param[3] unused
+ *
+ * Result:
+ * TEE_SUCCESS - Invoke command success
+ * TEE_ERROR_BAD_PARAMETERS - Incorrect input param
+ * TEE_ERROR_NOT_SUPPORTED - Requested entropy size greater than size of pool
+ * TEE_ERROR_HEALTH_TEST_FAIL - Continuous health testing failed
+ */
+#define TA_CMD_GET_ENTROPY		0x0
+
+#define MAX_ENTROPY_REQ_SZ		SZ_4K
+
+#define TA_HWRNG_UUID { 0xab7a617c, 0xb8e7, 0x4d8f, \
+			{ 0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64 } }
+
+/**
+ * struct optee_rng_priv - OP-TEE Random Number Generator private data
+ * @session_id:		RNG TA session identifier.
+ */
+struct optee_rng_priv {
+	u32 session_id;
+};
+
+static int get_optee_rng_data(struct udevice *dev,
+			      struct tee_shm *entropy_shm_pool,
+			      void *buf, size_t *size)
+{
+	struct optee_rng_priv *priv = dev_get_priv(dev);
+	int ret = 0;
+	struct tee_invoke_arg arg;
+	struct tee_param param;
+
+	memset(&arg, 0, sizeof(arg));
+	memset(&param, 0, sizeof(param));
+
+	/* Invoke TA_CMD_GET_ENTROPY function of Trusted App */
+	arg.func = TA_CMD_GET_ENTROPY;
+	arg.session = priv->session_id;
+
+	/* Fill invoke cmd params */
+	param.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
+	param.u.memref.shm = entropy_shm_pool;
+	param.u.memref.size = *size;
+
+	ret = tee_invoke_func(dev->parent, &arg, 1, &param);
+	if (ret || arg.ret) {
+		if (!ret)
+			ret = -EPROTO;
+		dev_err(dev, "TA_CMD_GET_ENTROPY invoke err: %d 0x%x\n", ret, arg.ret);
+		*size = 0;
+
+		return ret;
+	}
+
+	memcpy(buf, param.u.memref.shm->addr, param.u.memref.size);
+	*size = param.u.memref.size;
+
+	return 0;
+}
+
+static int optee_rng_read(struct udevice *dev, void *buf, size_t len)
+{
+	size_t read = 0, rng_size = 0;
+	struct tee_shm *entropy_shm_pool;
+	u8 *data = buf;
+	int ret;
+
+	ret = tee_shm_alloc(dev->parent, MAX_ENTROPY_REQ_SZ, 0, &entropy_shm_pool);
+	if (ret) {
+		dev_err(dev, "tee_shm_alloc failed: %d\n", ret);
+		return ret;
+	}
+
+	while (read < len) {
+		rng_size = min(len - read, (size_t)MAX_ENTROPY_REQ_SZ);
+		ret = get_optee_rng_data(dev, entropy_shm_pool, data, &rng_size);
+		if (ret)
+			goto shm_free;
+		data += rng_size;
+		read += rng_size;
+	}
+
+shm_free:
+	tee_shm_free(entropy_shm_pool);
+
+	return ret;
+}
+
+static int optee_rng_probe(struct udevice *dev)
+{
+	const struct tee_optee_ta_uuid uuid = TA_HWRNG_UUID;
+	struct optee_rng_priv *priv = dev_get_priv(dev);
+	struct tee_open_session_arg sess_arg;
+	int ret;
+
+	memset(&sess_arg, 0, sizeof(sess_arg));
+
+	/* Open session with hwrng Trusted App */
+	tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
+	sess_arg.clnt_login = TEE_LOGIN_PUBLIC;
+
+	ret = tee_open_session(dev->parent, &sess_arg, 0, NULL);
+	if (ret || sess_arg.ret) {
+		if (!ret)
+			ret = -EIO;
+		dev_err(dev, "can't open session: %d 0x%x\n", ret, sess_arg.ret);
+		return ret;
+	}
+	priv->session_id = sess_arg.session;
+
+	return 0;
+}
+
+static int optee_rng_remove(struct udevice *dev)
+{
+	struct optee_rng_priv *priv = dev_get_priv(dev);
+
+	tee_close_session(dev->parent, priv->session_id);
+
+	return 0;
+}
+
+static const struct dm_rng_ops optee_rng_ops = {
+	.read = optee_rng_read,
+};
+
+U_BOOT_DRIVER(optee_rng) = {
+	.name = "optee-rng",
+	.id = UCLASS_RNG,
+	.ops = &optee_rng_ops,
+	.probe = optee_rng_probe,
+	.remove = optee_rng_remove,
+	.priv_auto = sizeof(struct optee_rng_priv),
+};