Return-Path: Received: from mail-it1-f193.google.com ([209.85.166.193]:50375 "EHLO mail-it1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730497AbeL1KiY (ORCPT ); Fri, 28 Dec 2018 05:38:24 -0500 Received: by mail-it1-f193.google.com with SMTP id z7so27877330iti.0 for ; Fri, 28 Dec 2018 02:38:23 -0800 (PST) MIME-Version: 1.0 References: <1545908831-25910-1-git-send-email-sumit.garg@linaro.org> <1545908831-25910-3-git-send-email-sumit.garg@linaro.org> In-Reply-To: From: Ard Biesheuvel Date: Fri, 28 Dec 2018 11:38:10 +0100 Message-ID: Subject: Re: [PATCH v1 2/2] hwrng: add OP-TEE based rng driver To: Sumit Garg Cc: "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , Devicetree List , mpm@selenic.com, Herbert Xu , Rob Herring , Mark Rutland , Arnd Bergmann , Greg Kroah-Hartman , Jens Wiklander , Daniel Thompson , Bhupesh Sharma , tee-dev@lists.linaro.org Content-Type: text/plain; charset="UTF-8" Sender: linux-crypto-owner@vger.kernel.org List-ID: On Fri, 28 Dec 2018 at 10:58, Sumit Garg wrote: > > Thanks Ard for your comments. > > On Thu, 27 Dec 2018 at 23:58, Ard Biesheuvel wrote: > > > > On Thu, 27 Dec 2018 at 12:08, 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. > > > > > > 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 | 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 > > > > Please double check UUID in device tree (probably via dtc dump). > I have added this to the DT: --- a/Silicon/Socionext/SynQuacer/DeviceTree/SynQuacer.dtsi +++ b/Silicon/Socionext/SynQuacer/DeviceTree/SynQuacer.dtsi @@ -583,6 +583,7 @@ compatible = "linaro,optee-tz"; method = "smc"; status = "disabled"; + rng-uuid = "ab7a617c-b8e7-4d8f-8301-d09b61036b64"; }; }; }; > > (note that I need to run teesupplicant or the insmod just hangs) > > > > Actually OP-TEE tries to find TA in following order: > > 1. early/pseudo TAs (resident). > 2. Dynamic TAs (loaded at runtime). > > So if it doesn't find early/pseudo TAs then it tries to load dynamic > TAs via tee-supplicant. It seems that its probably stuck in > "optee_supp_thrd_req" (drivers/tee/optee/supp.c +85) where it waits > for supplicant to fulfil the request. > > I think this should be resolved via TEE bus driver approach that I > have proposed in previous patch. > It would be useful if we could detect the absence of teesupplicant rather than wait indefinitely. Currenty, we cannot make the RNG driver a builtin due to this, so please add 'depends on m' as a dependency if we don't resolve this in the short term. > > 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. > > > > Probably via TEE bus driver approach we may get rid of DT or ACPI > dependency. BTW, I will switch to platform device as it looks more > appropriate. > The bus driver approach only makes sense if we can enumerate the available TAs, rather than describe them via the DT or ACPI tables. But a child node with its own compatible string is an improvement in any case, and you can let the driver core instantiate the platform device for you. > > > diff --git a/MAINTAINERS b/MAINTAINERS > > > index 0767f1d..fe0fb74 100644 > > > --- a/MAINTAINERS > > > +++ b/MAINTAINERS > > > @@ -11100,6 +11100,11 @@ 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..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 > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > + > > > +#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 > > > > Will fix. > > > > + > > > +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. > > > > Yeah, we may not need this in case we go via TEE bus driver approach. > > > > + 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 "); > > > +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. > > > > Agree. > > > > -- > > > 2.7.4 > > >