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(¶m, 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, ¶m); + 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