linux/drivers/char/hw_random/optee-rng.c

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// 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)
{
int ret = 0;
u8 *rng_data = NULL;
size_t rng_size = 0;
struct tee_ioctl_invoke_arg inv_arg;
struct tee_param param[4];
memset(&inv_arg, 0, sizeof(inv_arg));
memset(&param, 0, sizeof(param));
/* 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)
{
int ret = 0;
struct tee_ioctl_invoke_arg inv_arg;
struct tee_param param[4];
memset(&inv_arg, 0, sizeof(inv_arg));
memset(&param, 0, sizeof(param));
/* 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;
memset(&sess_arg, 0, sizeof(sess_arg));
/* 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;
}
static 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");