Return-Path: Received: from mail-wm1-f66.google.com ([209.85.128.66]:35121 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727768AbfAJO1X (ORCPT ); Thu, 10 Jan 2019 09:27:23 -0500 Received: by mail-wm1-f66.google.com with SMTP id t200so12347360wmt.0 for ; Thu, 10 Jan 2019 06:27:21 -0800 (PST) Date: Thu, 10 Jan 2019 14:27:17 +0000 From: Daniel Thompson To: Sumit Garg Cc: linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, jens.wiklander@linaro.org, mpm@selenic.com, herbert@gondor.apana.org.au, robh+dt@kernel.org, mark.rutland@arm.com, arnd@arndb.de, gregkh@linuxfoundation.org, ard.biesheuvel@linaro.org, bhsharma@redhat.com, tee-dev@lists.linaro.org Subject: Re: [PATCH v2 4/4] hwrng: add OP-TEE based rng driver Message-ID: <20190110142717.ecktwvxp6qbr55be@holly.lan> References: <1547123097-16431-1-git-send-email-sumit.garg@linaro.org> <1547123097-16431-5-git-send-email-sumit.garg@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1547123097-16431-5-git-send-email-sumit.garg@linaro.org> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, Jan 10, 2019 at 05:54:57PM +0530, Sumit Garg 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. > > This driver registers on TEE bus to interact with OP-TEE based rng > device/service. > > Signed-off-by: Sumit Garg > --- > MAINTAINERS | 5 + > drivers/char/hw_random/Kconfig | 15 ++ > drivers/char/hw_random/Makefile | 1 + > drivers/char/hw_random/optee-rng.c | 272 +++++++++++++++++++++++++++++++++++++ > 4 files changed, 293 insertions(+) > create mode 100644 drivers/char/hw_random/optee-rng.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 32d44447..502733c 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -11260,6 +11260,11 @@ M: Jens Wiklander > S: Maintained > F: drivers/tee/optee/ > > +OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER > +M: Sumit Garg > +S: Maintained > +F: drivers/char/hw_random/optee-rng.c > + > OPA-VNIC DRIVER > M: Dennis Dalessandro > M: Niranjana Vishwanathapura > 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..ebfe1f2c > --- /dev/null > +++ b/drivers/char/hw_random/optee-rng.c > @@ -0,0 +1,272 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2018-2019 Linaro Ltd. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#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) > + > +static struct tee_context *ctx; > +static struct tee_shm *entropy_shm_pool; > +static u32 ta_rng_data_rate; > +static u32 ta_rng_session_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_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 = 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); You have a real device now! Almost all of the pr_xxx functions can become dev_xxx instead. > + 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 = DRIVER_NAME, > + .init = optee_rng_init, > + .cleanup = optee_rng_cleanup, > + .read = optee_rng_read, > +}; > + > +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_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(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 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 */ > + 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, 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(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_session_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_session_id); > +out_ctx: > + tee_client_close_context(ctx); > + > + return err; > +} > + > +static int optee_rng_remove(struct device *dev) > +{ > + tee_client_close_session(ctx, ta_rng_session_id); > + tee_client_close_context(ctx); > + hwrng_unregister(&optee_rng); > + > + 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)}, > + {} > +}; > + > +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 mod_init(void) Not required for correctness but for grepability I'd prefer optee_rng_init . Daniel. > +{ > + int rc; > + > + rc = driver_register(&optee_rng_driver.driver); > + if (rc) > + pr_warn("driver registration failed, err: %d", rc); > + > + return rc; > +} > + > +static void __exit mod_exit(void) > +{ > + driver_unregister(&optee_rng_driver.driver); > +} > + > +module_init(mod_init); > +module_exit(mod_exit); > + > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Sumit Garg "); > +MODULE_DESCRIPTION("OP-TEE based random number generator driver"); > -- > 2.7.4 >