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hwrng: add OP-TEE based rng 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.

This driver registers on TEE bus to interact with OP-TEE based rng
device/service.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
This commit is contained in:
Sumit Garg 2019-01-29 11:19:38 +05:30 committed by Jens Wiklander
parent c3fa24af92
commit 5fe8b1cc6a
4 changed files with 319 additions and 0 deletions
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5
MAINTAINERS
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@ -11262,6 +11262,11 @@ 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>

15
drivers/char/hw_random/Kconfig
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@ -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

1
drivers/char/hw_random/Makefile
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@ -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

298
drivers/char/hw_random/optee-rng.c Normal file
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@ -0,0 +1,298 @@
// 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)
/**
* struct optee_rng_private - OP-TEE Random Number Generator private data
* @dev: OP-TEE based RNG device.
* @ctx: OP-TEE context handler.
* @session_id: RNG TA session identifier.
* @data_rate: RNG data rate.
* @entropy_shm_pool: Memory pool shared with RNG device.
* @optee_rng: OP-TEE RNG driver structure.
*/
struct optee_rng_private {
struct device *dev;
struct tee_context *ctx;
u32 session_id;
u32 data_rate;
struct tee_shm *entropy_shm_pool;
struct hwrng optee_rng;
};
#define to_optee_rng_private(r) \
container_of(r, struct optee_rng_private, optee_rng)
static size_t get_optee_rng_data(struct optee_rng_private *pvt_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_ENTROPY function of Trusted App */
inv_arg.func = TA_CMD_GET_ENTROPY;
inv_arg.session = pvt_data->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 = pvt_data->entropy_shm_pool;
param[0].u.memref.size = req_size;
param[0].u.memref.shm_offs = 0;
ret = tee_client_invoke_func(pvt_data->ctx, &inv_arg, param);
if ((ret < 0) || (inv_arg.ret != 0)) {
dev_err(pvt_data->dev, "TA_CMD_GET_ENTROPY invoke err: %x\n",
inv_arg.ret);
return 0;
}
rng_data = tee_shm_get_va(pvt_data->entropy_shm_pool, 0);
if (IS_ERR(rng_data)) {
dev_err(pvt_data->dev, "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)
{
struct optee_rng_private *pvt_data = to_optee_rng_private(rng);
size_t read = 0, rng_size = 0;
int timeout = 1;
u8 *data = buf;
if (max > MAX_ENTROPY_REQ_SZ)
max = MAX_ENTROPY_REQ_SZ;
while (read == 0) {
rng_size = get_optee_rng_data(pvt_data, data, (max - read));
data += rng_size;
read += rng_size;
if (wait) {
if (timeout-- == 0)
return read;
msleep((1000 * (max - read)) / pvt_data->data_rate);
} else {
return read;
}
}
return read;
}
static int optee_rng_init(struct hwrng *rng)
{
struct optee_rng_private *pvt_data = to_optee_rng_private(rng);
struct tee_shm *entropy_shm_pool = NULL;
entropy_shm_pool = tee_shm_alloc(pvt_data->ctx, MAX_ENTROPY_REQ_SZ,
TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
if (IS_ERR(entropy_shm_pool)) {
dev_err(pvt_data->dev, "tee_shm_alloc failed\n");
return PTR_ERR(entropy_shm_pool);
}
pvt_data->entropy_shm_pool = entropy_shm_pool;
return 0;
}
static void optee_rng_cleanup(struct hwrng *rng)
{
struct optee_rng_private *pvt_data = to_optee_rng_private(rng);
tee_shm_free(pvt_data->entropy_shm_pool);
}
static struct optee_rng_private pvt_data = {
.optee_rng = {
.name = DRIVER_NAME,
.init = optee_rng_init,
.cleanup = optee_rng_cleanup,
.read = optee_rng_read,
}
};
static int get_optee_rng_info(struct device *dev)
{
u32 ret = 0;
struct tee_ioctl_invoke_arg inv_arg = {0};
struct tee_param param[4] = {0};
/* Invoke TA_CMD_GET_RNG_INFO function of Trusted App */
inv_arg.func = TA_CMD_GET_RNG_INFO;
inv_arg.session = pvt_data.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(pvt_data.ctx, &inv_arg, param);
if ((ret < 0) || (inv_arg.ret != 0)) {
dev_err(dev, "TA_CMD_GET_RNG_INFO invoke err: %x\n",
inv_arg.ret);
return -EINVAL;
}
pvt_data.data_rate = param[0].u.value.a;
pvt_data.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 */
pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
NULL);
if (IS_ERR(pvt_data.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(pvt_data.ctx, &sess_arg, NULL);
if ((ret < 0) || (sess_arg.ret != 0)) {
dev_err(dev, "tee_client_open_session failed, err: %x\n",
sess_arg.ret);
err = -EINVAL;
goto out_ctx;
}
pvt_data.session_id = sess_arg.session;
err = get_optee_rng_info(dev);
if (err)
goto out_sess;
err = hwrng_register(&pvt_data.optee_rng);
if (err) {
dev_err(dev, "hwrng registration failed (%d)\n", err);
goto out_sess;
}
pvt_data.dev = dev;
return 0;
out_sess:
tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
out_ctx:
tee_client_close_context(pvt_data.ctx);
return err;
}
static int optee_rng_remove(struct device *dev)
{
hwrng_unregister(&pvt_data.optee_rng);
tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
tee_client_close_context(pvt_data.ctx);
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)},
{}
};
MODULE_DEVICE_TABLE(tee, optee_rng_id_table);
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 optee_rng_mod_init(void)
{
return driver_register(&optee_rng_driver.driver);
}
static void __exit optee_rng_mod_exit(void)
{
driver_unregister(&optee_rng_driver.driver);
}
module_init(optee_rng_mod_init);
module_exit(optee_rng_mod_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Sumit Garg <sumit.garg@linaro.org>");
MODULE_DESCRIPTION("OP-TEE based random number generator driver");