@@ -11100,6 +11100,11 @@ 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>
@@ -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
@@ -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
new file mode 100644
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 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/tee_drv.h>
+#include <linux/uuid.h>
+
+#define PFX KBUILD_MODNAME ": "
+
+#define TEE_ERROR_HEALTH_TEST_FAIL 0x00000001
+
+/*
+ * TA_CMD_GET_ENTROPY - Get Entropy from RNG using Thermal Sensor
+ *
+ * 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 (4 * 1024)
+
+static struct tee_context *ctx;
+static struct tee_shm *entropy_shm_pool;
+static uuid_t ta_rng_uuid = {0};
+static u32 ta_rng_data_rate;
+static u32 ta_rng_seesion_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_seesion_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(PFX "tee_client_invoke_func failed, 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(PFX "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 = max / MAX_ENTROPY_REQ_SZ + 1;
+
+ /* New random numbers are generated approximately 1byte per 2ms */
+ while (read < max) {
+ if ((max - read) < MAX_ENTROPY_REQ_SZ)
+ rng_size = get_optee_rng_data(data, (max - read));
+ else
+ rng_size = get_optee_rng_data(data, MAX_ENTROPY_REQ_SZ);
+
+ data += rng_size;
+ read += rng_size;
+
+ if (wait) {
+ if (timeout-- == 0)
+ return read;
+ if ((max - read) < MAX_ENTROPY_REQ_SZ)
+ msleep((1000 * (max - read)) /
+ ta_rng_data_rate);
+ else
+ msleep((1000 * MAX_ENTROPY_REQ_SZ) /
+ ta_rng_data_rate);
+ } else {
+ return read;
+ }
+ }
+
+ return read;
+}
+
+static int optee_rng_init(struct hwrng *rng)
+{
+ int ret = 0, err = 0;
+ struct tee_ioctl_open_session_arg sess_arg = {0};
+
+ /* Open session with hwrng Trusted App */
+ memcpy(sess_arg.uuid, ta_rng_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(PFX "tee_client_open_session failed, error: %x\n",
+ sess_arg.ret);
+ err = -EINVAL;
+ goto out_ctx;
+ }
+ ta_rng_seesion_id = sess_arg.session;
+
+ 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(PFX "tee_shm_alloc failed\n");
+ err = PTR_ERR(entropy_shm_pool);
+ goto out_sess;
+ }
+
+ return 0;
+
+out_sess:
+ tee_client_close_session(ctx, ta_rng_seesion_id);
+out_ctx:
+ tee_client_close_context(ctx);
+
+ return err;
+}
+
+static void optee_rng_cleanup(struct hwrng *rng)
+{
+ tee_shm_free(entropy_shm_pool);
+ tee_client_close_session(ctx, ta_rng_seesion_id);
+}
+
+static struct hwrng optee_rng = {
+ .name = "optee-rng",
+ .init = optee_rng_init,
+ .cleanup = optee_rng_cleanup,
+ .read = optee_rng_read,
+};
+
+static int get_optee_hwrng_params(void)
+{
+ struct device_node *np;
+ const char *uuid;
+ u32 quality;
+
+ /* Node is supposed to be below /firmware/optee */
+ np = of_find_node_by_path("/firmware/optee/hw-rng");
+ if (!np)
+ return -ENODEV;
+
+ if (of_property_read_string(np, "uuid", &uuid)) {
+ pr_warn(PFX "missing \"uuid\" property\n");
+ return -ENXIO;
+ }
+
+ if (uuid_parse(uuid, &ta_rng_uuid)) {
+ pr_warn(PFX "incorrect rng ta uuid\n");
+ return -EINVAL;
+ }
+
+ if (of_property_read_u32(np, "data-rate", &ta_rng_data_rate)) {
+ pr_warn(PFX "missing \"data-rate\" property\n");
+ return -ENXIO;
+ }
+
+ if (!of_property_read_u32(np, "quality", &quality))
+ optee_rng.quality = quality;
+
+ return 0;
+}
+
+static int tee_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 __init mod_init(void)
+{
+ int err = -ENODEV;
+
+ err = get_optee_hwrng_params();
+ if (err)
+ return err;
+
+ /* Open context with TEE driver */
+ ctx = tee_client_open_context(NULL, tee_match, NULL, NULL);
+ if (IS_ERR(ctx))
+ return -ENODEV;
+
+ err = hwrng_register(&optee_rng);
+ if (err) {
+ pr_err(PFX " registering failed (%d)\n", err);
+ return err;
+ }
+
+ return 0;
+}
+
+static void __exit mod_exit(void)
+{
+ tee_client_close_context(ctx);
+ hwrng_unregister(&optee_rng);
+}
+
+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");
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. 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 | 236 +++++++++++++++++++++++++++++++++++++ 4 files changed, 257 insertions(+) create mode 100644 drivers/char/hw_random/optee-rng.c -- 2.7.4