[PATCH] tpm2: ftpm: A driver for firmware TPM running inside TEE
Thirupathaiah Annapureddy
thiruan at linux.microsoft.com
Tue Feb 4 18:08:28 CET 2020
Hi All,
May I know what are the next steps in making forward progress on this?
Best Regards,
Thiru
On 1/12/2020 11:34 PM, Thirupathaiah Annapureddy wrote:
> Add a driver for a firmware TPM running inside TEE.
>
> Documentation of the firmware TPM:
> https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
>
> Implementation of the firmware TPM:
> https://github.com/Microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM
>
> Signed-off-by: Thirupathaiah Annapureddy <thiruan at linux.microsoft.com>
> ---
> drivers/tpm/Kconfig | 6 +
> drivers/tpm/Makefile | 1 +
> drivers/tpm/tpm2_ftpm_tee.c | 250 ++++++++++++++++++++++++++++++++++++
> drivers/tpm/tpm2_ftpm_tee.h | 35 +++++
> 4 files changed, 292 insertions(+)
> create mode 100644 drivers/tpm/tpm2_ftpm_tee.c
> create mode 100644 drivers/tpm/tpm2_ftpm_tee.h
>
> diff --git a/drivers/tpm/Kconfig b/drivers/tpm/Kconfig
> index 94629dffd2..81bbffc50d 100644
> --- a/drivers/tpm/Kconfig
> +++ b/drivers/tpm/Kconfig
> @@ -145,6 +145,12 @@ config TPM2_TIS_SPI
> to the device using the standard TPM Interface Specification (TIS)
> protocol.
>
> +config TPM2_FTPM_TEE
> + bool "TEE based fTPM Interface"
> + depends on TEE && OPTEE && TPM_V2
> + help
> + This driver supports firmware TPM running in TEE.
> +
> endif # TPM_V2
>
> endmenu
> diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
> index 94c337b8ed..b1be3feac8 100644
> --- a/drivers/tpm/Makefile
> +++ b/drivers/tpm/Makefile
> @@ -12,3 +12,4 @@ obj-$(CONFIG_TPM_ST33ZP24_SPI) += tpm_tis_st33zp24_spi.o
>
> obj-$(CONFIG_TPM2_TIS_SANDBOX) += tpm2_tis_sandbox.o
> obj-$(CONFIG_TPM2_TIS_SPI) += tpm2_tis_spi.o
> +obj-$(CONFIG_TPM2_FTPM_TEE) += tpm2_ftpm_tee.o
> diff --git a/drivers/tpm/tpm2_ftpm_tee.c b/drivers/tpm/tpm2_ftpm_tee.c
> new file mode 100644
> index 0000000000..4b79d4ada0
> --- /dev/null
> +++ b/drivers/tpm/tpm2_ftpm_tee.c
> @@ -0,0 +1,250 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) Microsoft Corporation
> + *
> + * Authors:
> + * Thirupathaiah Annapureddy <thiruan at microsoft.com>
> + *
> + * Description:
> + * Device Driver for 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 <common.h>
> +#include <dm.h>
> +#include <tpm-v2.h>
> +#include <tee.h>
> +
> +#include "tpm_tis.h"
> +#include "tpm2_ftpm_tee.h"
> +
> +/**
> + * ftpm_tee_transceive() - send fTPM commands and retrieve fTPM response.
> + * @sendbuf - address of the data to send, byte by byte
> + * @send_size - length of the data to send
> + * @recvbuf - address where to read the response, byte by byte.
> + * @recv_len - pointer to the size of buffer
> + *
> + * Return:
> + * In case of success, returns 0.
> + * On failure, -errno
> + */
> +static int ftpm_tee_transceive(struct udevice *dev, const u8 *sendbuf,
> + size_t send_size, u8 *recvbuf,
> + size_t *recv_len)
> +{
> + struct ftpm_tee_private *context = dev_get_priv(dev);
> + int rc = 0;
> + size_t resp_len;
> + u8 *resp_buf;
> + struct tpm_output_header *resp_header;
> + struct tee_invoke_arg transceive_args;
> + struct tee_param command_params[4];
> + struct tee_shm *shm;
> +
> + if (send_size > MAX_COMMAND_SIZE) {
> + debug("%s:send_size=%zd exceeds MAX_COMMAND_SIZE\n",
> + __func__, send_size);
> + return -EIO;
> + }
> +
> + shm = context->shm;
> + memset(&transceive_args, 0, sizeof(transceive_args));
> + memset(command_params, 0, sizeof(command_params));
> +
> + /* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
> + transceive_args = (struct tee_invoke_arg) {
> + .func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
> + .session = context->session,
> + };
> +
> + /* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
> + /* request */
> + command_params[0] = (struct tee_param) {
> + .attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
> + .u.memref = {
> + .shm = shm,
> + .size = send_size,
> + .shm_offs = 0,
> + },
> + };
> + memset(command_params[0].u.memref.shm->addr, 0,
> + (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
> + memcpy(command_params[0].u.memref.shm->addr, sendbuf, send_size);
> +
> + /* response */
> + command_params[1] = (struct tee_param) {
> + .attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT,
> + .u.memref = {
> + .shm = shm,
> + .size = MAX_RESPONSE_SIZE,
> + .shm_offs = MAX_COMMAND_SIZE,
> + },
> + };
> +
> + rc = tee_invoke_func(context->tee_dev, &transceive_args, 4,
> + command_params);
> + if ((rc < 0) || (transceive_args.ret != 0)) {
> + debug("%s:SUBMIT_COMMAND invoke error: 0x%x\n",
> + __func__, transceive_args.ret);
> + return (rc < 0) ? rc : transceive_args.ret;
> + }
> +
> + resp_buf = command_params[1].u.memref.shm->addr +
> + command_params[1].u.memref.shm_offs;
> + resp_header = (struct tpm_output_header *)resp_buf;
> + resp_len = be32_to_cpu(resp_header->length);
> +
> + /* sanity check resp_len*/
> + if (resp_len < TPM_HEADER_SIZE) {
> + debug("%s:tpm response header too small\n", __func__);
> + return -EIO;
> + }
> + if (resp_len > MAX_RESPONSE_SIZE) {
> + debug("%s:resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
> + __func__, resp_len);
> + return -EIO;
> + }
> + if (resp_len > *recv_len) {
> + debug("%s:response length is bigger than receive buffer\n",
> + __func__);
> + return -EIO;
> + }
> +
> + /* sanity checks look good, copy the response */
> + memcpy(recvbuf, resp_buf, resp_len);
> + *recv_len = resp_len;
> +
> + return 0;
> +}
> +
> +static int ftpm_tee_open(struct udevice *dev)
> +{
> + struct ftpm_tee_private *context = dev_get_priv(dev);
> +
> + if (context->is_open)
> + return -EBUSY;
> +
> + context->is_open = 1;
> +
> + return 0;
> +}
> +
> +static int ftpm_tee_close(struct udevice *dev)
> +{
> + struct ftpm_tee_private *context = dev_get_priv(dev);
> +
> + if (context->is_open)
> + context->is_open = 0;
> +
> + return 0;
> +}
> +
> +static int ftpm_tee_desc(struct udevice *dev, char *buf, int size)
> +{
> + if (size < 32)
> + return -ENOSPC;
> +
> + return snprintf(buf, size, "Microsoft OP-TEE fTPM");
> +}
> +
> +static int ftpm_tee_match(struct tee_version_data *vers, const void *data)
> +{
> + debug("%s:vers->gen_caps =0x%x\n", __func__, vers->gen_caps);
> +
> + /*
> + * Currently this driver only support GP Complaint OPTEE based fTPM TA
> + */
> + return vers->gen_caps & TEE_GEN_CAP_GP;
> +}
> +
> +static int ftpm_tee_probe(struct udevice *dev)
> +{
> + int rc;
> + struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
> + struct ftpm_tee_private *context = dev_get_priv(dev);
> + struct tee_open_session_arg sess_arg;
> + const struct tee_optee_ta_uuid uuid = TA_FTPM_UUID;
> +
> + memset(context, 0, sizeof(*context));
> +
> + /* Use the TPM v2 stack */
> + priv->version = TPM_V2;
> + priv->pcr_count = 24;
> + priv->pcr_select_min = 3;
> +
> + /* Find TEE device */
> + context->tee_dev = tee_find_device(NULL, ftpm_tee_match, NULL, NULL);
> + if (!context->tee_dev) {
> + debug("%s:tee_find_device failed\n", __func__);
> + return -ENODEV;
> + }
> +
> + /* Open a session with the fTPM TA */
> + memset(&sess_arg, 0, sizeof(sess_arg));
> + tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
> +
> + rc = tee_open_session(context->tee_dev, &sess_arg, 0, NULL);
> + if ((rc < 0) || (sess_arg.ret != 0)) {
> + debug("%s:tee_open_session failed, err=%x\n",
> + __func__, sess_arg.ret);
> + return -EIO;
> + }
> + context->session = sess_arg.session;
> +
> + /* Allocate dynamic shared memory with fTPM TA */
> + rc = tee_shm_alloc(context->tee_dev,
> + MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
> + 0, &context->shm);
> + if (rc) {
> + debug("%s:tee_shm_alloc failed with rc = %d\n", __func__, rc);
> + goto out_shm_alloc;
> + }
> +
> + return 0;
> +
> +out_shm_alloc:
> + tee_close_session(context->tee_dev, context->session);
> +
> + return rc;
> +}
> +
> +static int ftpm_tee_remove(struct udevice *dev)
> +{
> + struct ftpm_tee_private *context = dev_get_priv(dev);
> + int rc;
> +
> + /* tee_pre_remove frees any leftover TEE shared memory */
> +
> + /* close the existing session with fTPM TA*/
> + rc = tee_close_session(context->tee_dev, context->session);
> + debug("%s: tee_close_session - rc =%d\n", __func__, rc);
> +
> + return 0;
> +}
> +
> +static const struct tpm_ops ftpm_tee_ops = {
> + .open = ftpm_tee_open,
> + .close = ftpm_tee_close,
> + .get_desc = ftpm_tee_desc,
> + .xfer = ftpm_tee_transceive,
> +};
> +
> +static const struct udevice_id ftpm_tee_ids[] = {
> + { .compatible = "microsoft,ftpm" },
> + { }
> +};
> +
> +U_BOOT_DRIVER(ftpm_tee) = {
> + .name = "ftpm_tee",
> + .id = UCLASS_TPM,
> + .of_match = ftpm_tee_ids,
> + .ops = &ftpm_tee_ops,
> + .probe = ftpm_tee_probe,
> + .remove = ftpm_tee_remove,
> + .flags = DM_FLAG_OS_PREPARE,
> + .priv_auto_alloc_size = sizeof(struct ftpm_tee_private),
> +};
> diff --git a/drivers/tpm/tpm2_ftpm_tee.h b/drivers/tpm/tpm2_ftpm_tee.h
> new file mode 100644
> index 0000000000..44f9598c28
> --- /dev/null
> +++ b/drivers/tpm/tpm2_ftpm_tee.h
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) Microsoft Corporation
> + */
> +
> +#ifndef __TPM2_FTPM_TEE_H__
> +#define __TPM2_FTPM_TEE_H__
> +
> +/* This UUID is generated with uuidgen */
> +#define TA_FTPM_UUID { 0xBC50D971, 0xD4C9, 0x42C4, \
> + {0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96} }
> +
> +/* 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
> +
> +/**
> + * struct ftpm_tee_private - fTPM's private context
> + * @tee_dev: struct udevice for TEE.
> + * @session: fTPM TA session identifier.
> + * @is_open: Indicates whether the driver is already opened by client or not.
> + * @shm: Memory pool shared with fTPM TA in TEE.
> + */
> +struct ftpm_tee_private {
> + struct udevice *tee_dev;
> + u32 session;
> + int is_open;
> + struct tee_shm *shm;
> +};
> +
> +#endif /* __TPM2_FTPM_TEE_H__ */
>
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