This patch adds support for a software-only implementation of a TPM running in TEE.
There is extensive documentation of the design here: https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/ . As well as reference code for the firmware available here: https://github.com/Microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM Signed-off-by: Thirupathaiah Annapureddy <thir...@microsoft.com> Signed-off-by: Sasha Levin <sas...@kernel.org> --- drivers/char/tpm/Kconfig | 5 + drivers/char/tpm/Makefile | 1 + drivers/char/tpm/tpm_ftpm_tee.c | 353 ++++++++++++++++++++++++++++++++ drivers/char/tpm/tpm_ftpm_tee.h | 61 ++++++ 4 files changed, 420 insertions(+) create mode 100644 drivers/char/tpm/tpm_ftpm_tee.c create mode 100644 drivers/char/tpm/tpm_ftpm_tee.h diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig index 536e55d3919f..5638726641eb 100644 --- a/drivers/char/tpm/Kconfig +++ b/drivers/char/tpm/Kconfig @@ -164,6 +164,11 @@ config TCG_VTPM_PROXY /dev/vtpmX and a server-side file descriptor on which the vTPM can receive commands. +config TCG_FTPM_TEE + tristate "TEE based fTPM Interface" + depends on TEE + ---help--- + This driver proxies for fTPM running in TEE source "drivers/char/tpm/st33zp24/Kconfig" endif # TCG_TPM diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile index a01c4cab902a..c354cdff9c62 100644 --- a/drivers/char/tpm/Makefile +++ b/drivers/char/tpm/Makefile @@ -33,3 +33,4 @@ obj-$(CONFIG_TCG_TIS_ST33ZP24) += st33zp24/ obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o obj-$(CONFIG_TCG_CRB) += tpm_crb.o obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o +obj-$(CONFIG_TCG_FTPM_TEE) += tpm_ftpm_tee.o diff --git a/drivers/char/tpm/tpm_ftpm_tee.c b/drivers/char/tpm/tpm_ftpm_tee.c new file mode 100644 index 000000000000..fdca9093a7bf --- /dev/null +++ b/drivers/char/tpm/tpm_ftpm_tee.c @@ -0,0 +1,353 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation + */ + +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/acpi.h> +#include <linux/platform_device.h> +#include <linux/tee_drv.h> +#include <linux/uuid.h> +#include <linux/tpm.h> + +#include "tpm.h" +#include "tpm_ftpm_tee.h" + +#define DRIVER_NAME "ftpm-tee" + +/* + * Note: ftpm_tee_tpm_op_recv and ftpm_tee_tpm_op_send are called from the + * same routine tpm_try_transmit in tpm-interface.c. These calls are protected + * by chip->tpm_mutex => There is no need for protecting any data shared + * between these routines ex: struct ftpm_tee_private + */ + +/* + * ftpm_tee_tpm_op_recv retrieve fTPM response. + * @param: chip, the tpm_chip description as specified in driver/char/tpm/tpm.h. + * @param: buf, the buffer to store data. + * @param: count, the number of bytes to read. + * @return: In case of success the number of bytes received. + * In other case, a < 0 value describing the issue. + */ +static int ftpm_tee_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count) +{ + struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent); + size_t len; + + len = pvt_data->resp_len; + dev_dbg(&chip->dev, "%s:len=%zd, resp_len=%zd\n", __func__, + count, len); + if (count < len) { + dev_err(&chip->dev, + "%s:Invalid size in recv: count=%zd, resp_len=%zd\n", + __func__, count, len); + return -EIO; + } + + memcpy(buf, pvt_data->resp_buf, len); + pvt_data->resp_len = 0; + + return len; +} + +/* + * ftpm_tee_tpm_op_send send TPM commands through the TEE shared memory. + * + * @param: chip, the tpm_chip description as specified in driver/char/tpm/tpm.h + * @param: buf, the buffer to send. + * @param: len, the number of bytes to send. + * @return: In case of success the number of bytes sent. + * In other case, a < 0 value describing the issue. + */ +static int ftpm_tee_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t len) +{ + struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent); + size_t resp_len; + int rc; + u8 *temp_buf; + struct tpm_header *resp_header; + struct tee_ioctl_invoke_arg transceive_args; + struct tee_param command_params[4]; + struct tee_shm *shm = pvt_data->shm; + + dev_dbg(&chip->dev, "%s:len=%zd\n", __func__, len); + + if (len > MAX_COMMAND_SIZE) { + dev_err(&chip->dev, + "%s:len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n", + __func__, len); + return -EIO; + } + + memset(&transceive_args, 0, sizeof(transceive_args)); + memset(command_params, 0, sizeof(command_params)); + pvt_data->resp_len = 0; + + /* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */ + transceive_args = (struct tee_ioctl_invoke_arg) { + .func = FTPM_OPTEE_TA_SUBMIT_COMMAND, + .session = pvt_data->session, + .num_params = 4, + }; + + /* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */ + command_params[0] = (struct tee_param) { + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT, + .u.memref = { + .shm = shm, + .size = len, + .shm_offs = 0, + }, + }; + + temp_buf = tee_shm_get_va(shm, 0); + if (IS_ERR(temp_buf)) { + dev_err(&chip->dev, "%s:tee_shm_get_va failed for transmit\n", + __func__); + return PTR_ERR(temp_buf); + } + memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE)); + + memcpy(temp_buf, buf, len); + + command_params[1] = (struct tee_param) { + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT, + .u.memref = { + .shm = shm, + .size = MAX_RESPONSE_SIZE, + .shm_offs = MAX_COMMAND_SIZE, + }, + }; + + rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args, + command_params); + if ((rc < 0) || (transceive_args.ret != 0)) { + dev_err(&chip->dev, "%s:SUBMIT_COMMAND invoke error: 0x%x\n", + __func__, transceive_args.ret); + return (rc < 0) ? rc : transceive_args.ret; + } + + temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs); + if (IS_ERR(temp_buf)) { + dev_err(&chip->dev, "%s:tee_shm_get_va failed for receive\n", + __func__); + return PTR_ERR(temp_buf); + } + + resp_header = (struct tpm_header *)temp_buf; + resp_len = be32_to_cpu(resp_header->length); + + /* sanity check resp_len */ + if (resp_len < TPM_HEADER_SIZE) { + dev_err(&chip->dev, "%s:tpm response header too small\n", + __func__); + return -EIO; + } + if (resp_len > MAX_RESPONSE_SIZE) { + dev_err(&chip->dev, + "%s:resp_len=%zd exceeds MAX_RESPONSE_SIZE\n", + __func__, resp_len); + return -EIO; + } + + /* sanity checks look good, cache the response */ + memcpy(pvt_data->resp_buf, temp_buf, resp_len); + pvt_data->resp_len = resp_len; + + return len; +} + +static void ftpm_tee_tpm_op_cancel(struct tpm_chip *chip) +{ + /* not supported */ +} + +static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip) +{ + return 0; +} + +static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status) +{ + return 0; +} + +static const struct tpm_class_ops ftpm_tee_tpm_ops = { + .flags = 0, + .recv = ftpm_tee_tpm_op_recv, + .send = ftpm_tee_tpm_op_send, + .cancel = ftpm_tee_tpm_op_cancel, + .status = ftpm_tee_tpm_op_status, + .req_complete_mask = 0, + .req_complete_val = 0, + .req_canceled = ftpm_tee_tpm_req_canceled, +}; + +/* + * Check whether this driver supports the fTPM TA in the TEE instance + * represented by the params (ver/data) to this function. + */ +static int ftpm_tee_match(struct tee_ioctl_version_data *ver, const void *data) +{ + pr_debug("%s:vers->gen_caps =0x%x\n", __func__, ver->gen_caps); + + /* + * Currently this driver only support GP Complaint OPTEE based fTPM TA + */ + if ((ver->impl_id == TEE_IMPL_ID_OPTEE) && + (ver->gen_caps & TEE_GEN_CAP_GP)) + return 1; + else + return 0; +} + +/* + * Undo what has been done in ftpm_tee_probe + */ +static void ftpm_tee_deinit(struct ftpm_tee_private *pvt_data) +{ + /* Release the chip */ + if (pvt_data->state & STATE_REGISTERED_FLAG) + tpm_chip_unregister(pvt_data->chip); + + if (pvt_data->ctx != NULL) { + + /* Free the shared memory pool */ + if (pvt_data->state & STATE_TEE_SHMALLOC_FLAG) + tee_shm_free(pvt_data->shm); + + /* close the existing session with fTPM TA*/ + if (pvt_data->state & STATE_TEE_OPENED_FLAG) + tee_client_close_session(pvt_data->ctx, + pvt_data->session); + + /* close the context with TEE driver */ + tee_client_close_context(pvt_data->ctx); + } + + /* memory allocated with devm_kzalloc() is freed automatically */ +} + +/* + * ftpm_tee_probe initialize the fTPM + * @param: pdev, the platform_device description. + * @return: 0 in case of success. + * or a negative value describing the error. + */ +static int ftpm_tee_probe(struct platform_device *pdev) +{ + int rc; + struct tpm_chip *chip; + struct device *dev = &pdev->dev; + struct ftpm_tee_private *pvt_data = NULL; + struct tee_ioctl_open_session_arg sess_arg; + + dev_dbg(dev, "%s++\n", __func__); + + pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private), + GFP_KERNEL); + if (!pvt_data) + return -ENOMEM; + + dev_set_drvdata(dev, pvt_data); + + /* Open context with TEE driver */ + pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL, + NULL); + if (IS_ERR(pvt_data->ctx)) { + dev_err(dev, "%s:tee_client_open_context failed\n", __func__); + return -EPROBE_DEFER; + } + + /* Open a session with fTPM TA*/ + memset(&sess_arg, 0, sizeof(sess_arg)); + memcpy(sess_arg.uuid, ftpm_ta_uuid.b, TEE_IOCTL_UUID_LEN); + sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC; + sess_arg.num_params = 0; + + rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL); + if ((rc < 0) || (sess_arg.ret != 0)) { + dev_err(dev, "%s:tee_client_open_session failed, err=%x\n", + __func__, sess_arg.ret); + rc = -EINVAL; + goto out; + } + pvt_data->session = sess_arg.session; + pvt_data->state |= STATE_TEE_OPENED_FLAG; + + /* Allocate dynamic shared memory with fTPM TA */ + pvt_data->shm = tee_shm_alloc(pvt_data->ctx, + (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE), + TEE_SHM_MAPPED | TEE_SHM_DMA_BUF); + if (IS_ERR(pvt_data->shm)) { + dev_err(dev, "%s:tee_shm_alloc failed\n", __func__); + rc = -ENOMEM; + goto out; + } + pvt_data->state |= STATE_TEE_SHMALLOC_FLAG; + + /* Allocate new struct tpm_chip instance */ + chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops); + if (IS_ERR(chip)) { + dev_err(dev, "%s:tpm_chip_alloc failed\n", __func__); + rc = PTR_ERR(chip); + goto out; + } + + pvt_data->chip = chip; + pvt_data->chip->flags |= TPM_CHIP_FLAG_TPM2; + + /* Create a character device for the fTPM */ + rc = tpm_chip_register(pvt_data->chip); + if (rc) { + dev_err(dev, "%s:tpm_chip_register failed with rc=%d\n", + __func__, rc); + goto out; + } + pvt_data->state |= STATE_REGISTERED_FLAG; + +out: + if (rc) + ftpm_tee_deinit(pvt_data); + + dev_dbg(dev, "%s-- rc = %d\n", __func__, rc); + + return rc; +} + +/* + * ftpm_tee_remove remove the TPM device + * @param: pdev, the platform_device description. + * @return: 0 in case of success. + */ +static int ftpm_tee_remove(struct platform_device *pdev) +{ + struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev); + + ftpm_tee_deinit(pvt_data); + + return 0; +} + +static const struct of_device_id of_ftpm_tee_ids[] = { + { .compatible = "microsoft,ftpm" }, + { } +}; +MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids); + +static struct platform_driver ftpm_tee_driver = { + .driver = { + .name = DRIVER_NAME, + .of_match_table = of_match_ptr(of_ftpm_tee_ids), + }, + .probe = ftpm_tee_probe, + .remove = ftpm_tee_remove, +}; + +module_platform_driver(ftpm_tee_driver); + +MODULE_AUTHOR("Thirupathaiah Annapureddy <thir...@microsoft.com>"); +MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE"); +MODULE_LICENSE("GPL v2"); diff --git a/drivers/char/tpm/tpm_ftpm_tee.h b/drivers/char/tpm/tpm_ftpm_tee.h new file mode 100644 index 000000000000..ea1a12c183ee --- /dev/null +++ b/drivers/char/tpm/tpm_ftpm_tee.h @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) Microsoft Corporation + */ + +#ifndef __TPM_FTPM_TEE_H__ +#define __TPM_FTPM_TEE_H__ + +#include <linux/tee_drv.h> +#include <linux/uuid.h> +#include <linux/tpm.h> + +/* The TAFs ID implemented in this TA */ +#define FTPM_OPTEE_TA_SUBMIT_COMMAND (0) +#define FTPM_OPTEE_TA_EMULATE_PPI (1) + +/* max. buffer size supported by fTPM */ +#define MAX_COMMAND_SIZE 4096 +#define MAX_RESPONSE_SIZE 4096 + +/* internal state flags borrowed from drivers/char/tpm/tpm_vtpm_proxy.c */ +#define STATE_OPENED_FLAG BIT(0) +#define STATE_WAIT_RESPONSE_FLAG BIT(1) /* waiting for emulator response */ +#define STATE_REGISTERED_FLAG BIT(2) +#define STATE_DRIVER_COMMAND BIT(3) /* sending a driver specific command */ +#define STATE_TEE_OPENED_FLAG BIT(4) /* TEE Session opened */ +#define STATE_TEE_SHMALLOC_FLAG BIT(5) /* TEE Shared memory is allocated */ + +/* + * struct ftpm_tee_private - fTPM's private data + * @chip: struct tpm_chip instance registered with tpm framework. + * @state: internal state + * @session: fTPM TA session identifier. + * @resp_len: cached response buffer length. + * @resp_buf: cached response buffer. + * @ctx: TEE context handler. + * @shm: Memory pool shared with fTPM TA in TEE. + */ +struct ftpm_tee_private { + struct tpm_chip *chip; + long state; + u32 session; + size_t resp_len; + u8 resp_buf[MAX_RESPONSE_SIZE]; + struct tee_context *ctx; + struct tee_shm *shm; +}; + +/* + * Note: ftpm_tee_tpm_op_recv and ftpm_tee_tpm_op_send are called from the + * same routine tpm_try_transmit in tpm-interface.c. These calls are protected + * by chip->tpm_mutex => There is no need for protecting any data shared + * between these routines ex: struct ftpm_tee_private + */ + +/* TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896 */ +static const uuid_t ftpm_ta_uuid = + UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4, + 0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96); + +#endif /* __TPM_FTPM_TEE_H__ */ -- 2.19.1
