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@xxxxxxxxxx>
---
MAINTAINERS | 5 +
drivers/char/hw_random/Kconfig | 15 ++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/optee-rng.c | 273 +++++++++++++++++++++++++++++++++++++
4 files changed, 294 insertions(+)
create mode 100644 drivers/char/hw_random/optee-rng.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 0767f1d..fe0fb74 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11100,6 +11100,11 @@ M: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
S: Maintained
F: drivers/tee/optee/
+OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER
+M: Sumit Garg <sumit.garg@xxxxxxxxxx>
+S: Maintained
+F: drivers/char/hw_random/optee-rng.c
+
OPA-VNIC DRIVER
M: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>
M: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
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..8c63730
--- /dev/null
+++ b/drivers/char/hw_random/optee-rng.c
@@ -0,0 +1,273 @@
+// 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 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_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("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 = "optee-rng",
+ .init = optee_rng_init,
+ .cleanup = optee_rng_cleanup,
+ .read = optee_rng_read,
+};
+
+static const struct of_device_id optee_match[] = {
+ { .compatible = "linaro,optee-tz" },
+ {},
+};
+
+static int get_optee_rng_uuid(uuid_t *ta_rng_uuid)
+{
+ struct device_node *fw_np;
+ struct device_node *np;
+ const char *uuid;
+
+ /* Node is supposed to be below /firmware */
+ fw_np = of_find_node_by_name(NULL, "firmware");
+ if (!fw_np)
+ return -ENODEV;
+
+ np = of_find_matching_node(fw_np, optee_match);
+ if (!np || !of_device_is_available(np))
+ return -ENODEV;
+
+ if (of_property_read_string(np, "rng-uuid", &uuid)) {
+ pr_warn("missing \"uuid\" property\n");
+ return -ENXIO;
+ }
+
+ if (uuid_parse(uuid, ta_rng_uuid)) {
+ pr_warn("incorrect rng ta uuid\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+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_seesion_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 __init mod_init(void)
+{
+ int ret = 0, err = -ENODEV;
+ struct tee_ioctl_open_session_arg sess_arg = {0};
+ uuid_t ta_rng_uuid = {0};
+
+ err = get_optee_rng_uuid(&ta_rng_uuid);
+ if (err)
+ return err;
+
+ /* 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, 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("tee_client_open_session failed, error: %x\n",
+ sess_arg.ret);
+ err = -EINVAL;
+ goto out_ctx;
+ }
+ ta_rng_seesion_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_seesion_id);
+out_ctx:
+ tee_client_close_context(ctx);
+
+ return err;
+}
+
+static void __exit mod_exit(void)
+{
+ tee_client_close_session(ctx, ta_rng_seesion_id);
+ 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@xxxxxxxxxx>");
+MODULE_DESCRIPTION("OP-TEE based random number generator driver");
+MODULE_SOFTDEP("pre: optee");
--
2.7.4
