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.delau...@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(¶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;
+}
+
+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),
+};
