On ARM SoC's with TrustZone enabled, peripherals like entropy sources might not be accessible to normal world (linux in this case) and rather accessible to secure world (OP-TEE in this case) only. So this driver aims to provides a generic interface to OP-TEE based random number generator service.
This driver registers on TEE bus to interact with OP-TEE based rng device/service.
Signed-off-by: Sumit Garg sumit.garg@linaro.org --- MAINTAINERS | 5 + drivers/char/hw_random/Kconfig | 15 ++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/optee-rng.c | 272 +++++++++++++++++++++++++++++++++++++ 4 files changed, 293 insertions(+) create mode 100644 drivers/char/hw_random/optee-rng.c
diff --git a/MAINTAINERS b/MAINTAINERS index 32d44447..502733c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -11260,6 +11260,11 @@ M: Jens Wiklander jens.wiklander@linaro.org S: Maintained F: drivers/tee/optee/
+OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER +M: Sumit Garg sumit.garg@linaro.org +S: Maintained +F: drivers/char/hw_random/optee-rng.c + OPA-VNIC DRIVER M: Dennis Dalessandro dennis.dalessandro@intel.com M: Niranjana Vishwanathapura niranjana.vishwanathapura@intel.com diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig index dac895d..25a7d8f 100644 --- a/drivers/char/hw_random/Kconfig +++ b/drivers/char/hw_random/Kconfig @@ -424,6 +424,21 @@ config HW_RANDOM_EXYNOS will be called exynos-trng.
If unsure, say Y. + +config HW_RANDOM_OPTEE + tristate "OP-TEE based Random Number Generator support" + depends on OPTEE + default HW_RANDOM + 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 (Linux). + + To compile this driver as a module, choose M here: the module + will be called optee-rng. + + If unsure, say Y. + endif # HW_RANDOM
config UML_RANDOM diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile index e35ec3c..7c9ef4a 100644 --- a/drivers/char/hw_random/Makefile +++ b/drivers/char/hw_random/Makefile @@ -38,3 +38,4 @@ obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o obj-$(CONFIG_HW_RANDOM_MTK) += mtk-rng.o obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o +obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o diff --git a/drivers/char/hw_random/optee-rng.c b/drivers/char/hw_random/optee-rng.c new file mode 100644 index 0000000..ebfe1f2c --- /dev/null +++ b/drivers/char/hw_random/optee-rng.c @@ -0,0 +1,272 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2018-2019 Linaro Ltd. + */ + +#include <linux/delay.h> +#include <linux/of.h> +#include <linux/hw_random.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/tee_drv.h> +#include <linux/uuid.h> + +#define DRIVER_NAME "optee-rng" + +#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 + +/* + * TA_CMD_GET_RNG_INFO - Get RNG information + * + * param[0] (out value) - value.a: RNG data-rate in bytes per second + * value.b: Quality/Entropy per 1024 bit of data + * param[1] unused + * param[2] unused + * param[3] unused + * + * Result: + * TEE_SUCCESS - Invoke command success + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param + */ +#define TA_CMD_GET_RNG_INFO 0x1 + +#define MAX_ENTROPY_REQ_SZ (4 * 1024) + +static struct tee_context *ctx; +static struct tee_shm *entropy_shm_pool; +static u32 ta_rng_data_rate; +static u32 ta_rng_session_id; + +static size_t get_optee_rng_data(void *buf, size_t req_size) +{ + u32 ret = 0; + u8 *rng_data = NULL; + size_t rng_size = 0; + struct tee_ioctl_invoke_arg inv_arg = {0}; + struct tee_param param[4] = {0}; + + /* Invoke TA_CMD_GET_RNG function of Trusted App */ + inv_arg.func = TA_CMD_GET_ENTROPY; + inv_arg.session = ta_rng_session_id; + inv_arg.num_params = 4; + + /* Fill invoke cmd params */ + param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT; + param[0].u.memref.shm = entropy_shm_pool; + param[0].u.memref.size = req_size; + param[0].u.memref.shm_offs = 0; + + ret = tee_client_invoke_func(ctx, &inv_arg, param); + if ((ret < 0) || (inv_arg.ret != 0)) { + pr_err("TA_CMD_GET_ENTROPY invoke function error: %x\n", + inv_arg.ret); + return 0; + } + + rng_data = tee_shm_get_va(entropy_shm_pool, 0); + if (IS_ERR(rng_data)) { + pr_err("tee_shm_get_va failed\n"); + return 0; + } + + rng_size = param[0].u.memref.size; + memcpy(buf, rng_data, rng_size); + + return rng_size; +} + +static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) +{ + u8 *data = buf; + size_t read = 0, rng_size = 0; + int timeout = 1; + + if (max > MAX_ENTROPY_REQ_SZ) + max = MAX_ENTROPY_REQ_SZ; + + while (read == 0) { + rng_size = get_optee_rng_data(data, (max - read)); + + data += rng_size; + read += rng_size; + + if (wait) { + if (timeout-- == 0) + return read; + msleep((1000 * (max - read)) / ta_rng_data_rate); + } else { + return read; + } + } + + return read; +} + +static int optee_rng_init(struct hwrng *rng) +{ + entropy_shm_pool = tee_shm_alloc(ctx, MAX_ENTROPY_REQ_SZ, + TEE_SHM_MAPPED | TEE_SHM_DMA_BUF); + if (IS_ERR(entropy_shm_pool)) { + pr_err("tee_shm_alloc failed\n"); + return PTR_ERR(entropy_shm_pool); + } + + return 0; +} + +static void optee_rng_cleanup(struct hwrng *rng) +{ + tee_shm_free(entropy_shm_pool); +} + +static struct hwrng optee_rng = { + .name = DRIVER_NAME, + .init = optee_rng_init, + .cleanup = optee_rng_cleanup, + .read = optee_rng_read, +}; + +static int get_optee_rng_info(void) +{ + u32 ret = 0; + struct tee_ioctl_invoke_arg inv_arg = {0}; + struct tee_param param[4] = {0}; + + /* Invoke TA_CMD_GET_RNG function of Trusted App */ + inv_arg.func = TA_CMD_GET_RNG_INFO; + inv_arg.session = ta_rng_session_id; + inv_arg.num_params = 4; + + /* Fill invoke cmd params */ + param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT; + + ret = tee_client_invoke_func(ctx, &inv_arg, param); + if ((ret < 0) || (inv_arg.ret != 0)) { + pr_err("TA_CMD_GET_RNG_INFO invoke function error: %x\n", + inv_arg.ret); + return -EINVAL; + } + + ta_rng_data_rate = param[0].u.value.a; + optee_rng.quality = param[0].u.value.b; + + return 0; +} + +static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data) +{ + if (ver->impl_id == TEE_IMPL_ID_OPTEE) + return 1; + else + return 0; +} + +static int optee_rng_probe(struct device *dev) +{ + struct tee_client_device *rng_device = to_tee_client_device(dev); + int ret = 0, err = -ENODEV; + struct tee_ioctl_open_session_arg sess_arg = {0}; + + /* Open context with TEE driver */ + ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, NULL); + if (IS_ERR(ctx)) + return -ENODEV; + + /* Open session with hwrng Trusted App */ + memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN); + sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC; + sess_arg.num_params = 0; + + ret = tee_client_open_session(ctx, &sess_arg, NULL); + if ((ret < 0) || (sess_arg.ret != 0)) { + pr_err("tee_client_open_session failed, error: %x\n", + sess_arg.ret); + err = -EINVAL; + goto out_ctx; + } + ta_rng_session_id = sess_arg.session; + + err = get_optee_rng_info(); + if (err) + goto out_sess; + + err = hwrng_register(&optee_rng); + if (err) { + pr_err("registering failed (%d)\n", err); + goto out_sess; + } + + return 0; + +out_sess: + tee_client_close_session(ctx, ta_rng_session_id); +out_ctx: + tee_client_close_context(ctx); + + return err; +} + +static int optee_rng_remove(struct device *dev) +{ + tee_client_close_session(ctx, ta_rng_session_id); + tee_client_close_context(ctx); + hwrng_unregister(&optee_rng); + + return 0; +} + +const struct tee_client_device_id optee_rng_id_table[] = { + {UUID_INIT(0xab7a617c, 0xb8e7, 0x4d8f, + 0x83, 0x01, 0xd0, 0x9b, 0x61, 0x03, 0x6b, 0x64)}, + {} +}; + +static struct tee_client_driver optee_rng_driver = { + .id_table = optee_rng_id_table, + .driver = { + .name = DRIVER_NAME, + .bus = &tee_bus_type, + .probe = optee_rng_probe, + .remove = optee_rng_remove, + }, +}; + +static int __init mod_init(void) +{ + int rc; + + rc = driver_register(&optee_rng_driver.driver); + if (rc) + pr_warn("driver registration failed, err: %d", rc); + + return rc; +} + +static void __exit mod_exit(void) +{ + driver_unregister(&optee_rng_driver.driver); +} + +module_init(mod_init); +module_exit(mod_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Sumit Garg sumit.garg@linaro.org"); +MODULE_DESCRIPTION("OP-TEE based random number generator driver");