// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) Microsoft Corporation
*
* Implements a firmware TPM as described here:
* https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
*
* A reference implementation is available here:
* https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
*/
#include <linux/acpi.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/tee_drv.h>
#include <linux/tpm.h>
#include <linux/uuid.h>
#include "tpm.h"
#include "tpm_ftpm_tee.h"
/*
* TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896
*
* Randomly generated, and must correspond to the GUID on the TA side.
* Defined here in the reference implementation:
* https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42
*/
static const uuid_t ftpm_ta_uuid =
UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);
/**
* ftpm_tee_tpm_op_recv() - retrieve fTPM response.
* @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h.
* @buf: the buffer to store data.
* @count: the number of bytes to read.
*
* Return:
* In case of success the number of bytes received.
* On failure, -errno.
*/
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;
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.
* @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h
* @buf: the buffer to send.
* @len: the number of bytes to send.
*
* Return:
* In case of success, returns 0.
* On failure, -errno
*/
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;
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 0;
}
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 false;
}
static const struct tpm_class_ops ftpm_tee_tpm_ops = {
.flags = TPM_OPS_AUTO_STARTUP,
.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)
{
/*
* 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;
}
/**
* ftpm_tee_probe() - initialize the fTPM
* @dev: the device description.
*
* Return:
* On success, 0. On failure, -errno.
*/
static int ftpm_tee_probe(struct device *dev)
{
int rc;
struct tpm_chip *chip;
struct ftpm_tee_private *pvt_data = NULL;
struct tee_ioctl_open_session_arg sess_arg;
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)) {
if (PTR_ERR(pvt_data->ctx) == -ENOENT)
return -EPROBE_DEFER;
dev_err(dev, "%s: tee_client_open_context failed\n", __func__);
return PTR_ERR(pvt_data->ctx);
}
/* Open a session with fTPM TA */
memset(&sess_arg, 0, sizeof(sess_arg));
export_uuid(sess_arg.uuid, &ftpm_ta_uuid);
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_tee_session;
}
pvt_data->session = sess_arg.session;
/* Allocate dynamic shared memory with fTPM TA */
pvt_data->shm = tee_shm_alloc_kernel_buf(pvt_data->ctx,
MAX_COMMAND_SIZE +
MAX_RESPONSE_SIZE);
if (IS_ERR(pvt_data->shm)) {
dev_err(dev, "%s: tee_shm_alloc_kernel_buf failed\n", __func__);
rc = -ENOMEM;
goto out_shm_alloc;
}
/* 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_chip_alloc;
}
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_chip;
}
return 0;
out_chip:
put_device(&pvt_data->chip->dev);
out_chip_alloc:
tee_shm_free(pvt_data->shm);
out_shm_alloc:
tee_client_close_session(pvt_data->ctx, pvt_data->session);
out_tee_session:
tee_client_close_context(pvt_data->ctx);
return rc;
}
static int ftpm_plat_tee_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
return ftpm_tee_probe(dev);
}
/**
* ftpm_tee_remove() - remove the TPM device
* @dev: the device description.
*
* Return:
* 0 always.
*/
static int ftpm_tee_remove(struct device *dev)
{
struct ftpm_tee_private *pvt_data = dev_get_drvdata(dev);
/* Release the chip */
tpm_chip_unregister(pvt_data->chip);
/* frees chip */
put_device(&pvt_data->chip->dev);
/* Free the shared memory pool */
tee_shm_free(pvt_data->shm);
/* close the existing session with fTPM TA*/
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 */
return 0;
}
static void ftpm_plat_tee_remove(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
ftpm_tee_remove(dev);
}
/**
* ftpm_plat_tee_shutdown() - shutdown the TPM device
* @pdev: the platform_device description.
*/
static void ftpm_plat_tee_shutdown(struct platform_device *pdev)
{
struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev);
tee_shm_free(pvt_data->shm);
tee_client_close_session(pvt_data->ctx, pvt_data->session);
tee_client_close_context(pvt_data->ctx);
}
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_plat_driver = {
.driver = {
.name = "ftpm-tee",
.of_match_table = of_match_ptr(of_ftpm_tee_ids),
},
.shutdown = ftpm_plat_tee_shutdown,
.probe = ftpm_plat_tee_probe,
.remove_new = ftpm_plat_tee_remove,
};
/* UUID of the fTPM TA */
static const struct tee_client_device_id optee_ftpm_id_table[] = {
{UUID_INIT(0xbc50d971, 0xd4c9, 0x42c4,
0x82, 0xcb, 0x34, 0x3f, 0xb7, 0xf3, 0x78, 0x96)},
{}
};
MODULE_DEVICE_TABLE(tee, optee_ftpm_id_table);
static struct tee_client_driver ftpm_tee_driver = {
.id_table = optee_ftpm_id_table,
.driver = {
.name = "optee-ftpm",
.bus = &tee_bus_type,
.probe = ftpm_tee_probe,
.remove = ftpm_tee_remove,
},
};
static int __init ftpm_mod_init(void)
{
int rc;
rc = platform_driver_register(&ftpm_tee_plat_driver);
if (rc)
return rc;
rc = driver_register(&ftpm_tee_driver.driver);
if (rc) {
platform_driver_unregister(&ftpm_tee_plat_driver);
return rc;
}
return 0;
}
static void __exit ftpm_mod_exit(void)
{
platform_driver_unregister(&ftpm_tee_plat_driver);
driver_unregister(&ftpm_tee_driver.driver);
}
module_init(ftpm_mod_init);
module_exit(ftpm_mod_exit);
MODULE_AUTHOR("Thirupathaiah Annapureddy <[email protected]>");
MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE");
MODULE_LICENSE("GPL v2");
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