On Thu, 27 Dec 2018 at 12:08, Sumit Garg <sumit.g...@linaro.org> wrote:
>
> 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.g...@linaro.org>
> ---
> 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
>
Hi Sumit,
I am having some trouble with this driver. Even though the firmware
manages to invoke the pseudo-TA, the kernel driver responds with
[ 73.915971] tee_client_open_session failed, error: ffff0008
(note that I need to run teesupplicant or the insmod just hangs)
Also, I have some concerns about the DT dependency (see my comment on
the previous patch)
I will cc you on some patches I have to expose OP-TEE via ACPI (as
well as DT) as a platform device. I'd prefer it if we could do the
same for this driver in one way or the other.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0767f1d..fe0fb74 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11100,6 +11100,11 @@ M: Jens Wiklander <jens.wiklan...@linaro.org>
> S: Maintained
> F: drivers/tee/optee/
>
> +OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER
> +M: Sumit Garg <sumit.g...@linaro.org>
> +S: Maintained
> +F: drivers/char/hw_random/optee-rng.c
> +
> OPA-VNIC DRIVER
> M: Dennis Dalessandro <dennis.dalessan...@intel.com>
> M: Niranjana Vishwanathapura <niranjana.vishwanathap...@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..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;
session not seesion
> +
> +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;
> + }
> +
So, duplicating all of this is really not a good idea.
> + 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.g...@linaro.org>");
> +MODULE_DESCRIPTION("OP-TEE based random number generator driver");
> +MODULE_SOFTDEP("pre: optee");
This is also an indicator that the API design needs some work. If the
OP-TEE driver becomes a 'bus' driver of some sort, the child RNG
device (which is what this driver should bind to) will only exist if
a) the OP-TEE driver is loaded, and b) it has actually bound to the
/firmware/optee node.
> --
> 2.7.4
>
