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![Thirupathaiah Annapureddy](/assets/img/avatar_default.png)
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@linux.microsoft.com>
251 lines
6.2 KiB
C
251 lines
6.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) Microsoft Corporation
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*
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* Authors:
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* Thirupathaiah Annapureddy <thiruan@microsoft.com>
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*
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* Description:
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* Device Driver for a firmware TPM as described here:
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* https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
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*
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* A reference implementation is available here:
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* https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
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*/
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#include <common.h>
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#include <dm.h>
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#include <tpm-v2.h>
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#include <tee.h>
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#include "tpm_tis.h"
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#include "tpm2_ftpm_tee.h"
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/**
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* ftpm_tee_transceive() - send fTPM commands and retrieve fTPM response.
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* @sendbuf - address of the data to send, byte by byte
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* @send_size - length of the data to send
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* @recvbuf - address where to read the response, byte by byte.
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* @recv_len - pointer to the size of buffer
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*
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* Return:
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* In case of success, returns 0.
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* On failure, -errno
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*/
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static int ftpm_tee_transceive(struct udevice *dev, const u8 *sendbuf,
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size_t send_size, u8 *recvbuf,
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size_t *recv_len)
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{
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struct ftpm_tee_private *context = dev_get_priv(dev);
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int rc = 0;
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size_t resp_len;
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u8 *resp_buf;
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struct tpm_output_header *resp_header;
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struct tee_invoke_arg transceive_args;
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struct tee_param command_params[4];
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struct tee_shm *shm;
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if (send_size > MAX_COMMAND_SIZE) {
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debug("%s:send_size=%zd exceeds MAX_COMMAND_SIZE\n",
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__func__, send_size);
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return -EIO;
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}
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shm = context->shm;
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memset(&transceive_args, 0, sizeof(transceive_args));
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memset(command_params, 0, sizeof(command_params));
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/* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
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transceive_args = (struct tee_invoke_arg) {
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.func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
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.session = context->session,
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};
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/* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
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/* request */
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command_params[0] = (struct tee_param) {
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.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
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.u.memref = {
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.shm = shm,
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.size = send_size,
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.shm_offs = 0,
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},
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};
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memset(command_params[0].u.memref.shm->addr, 0,
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(MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
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memcpy(command_params[0].u.memref.shm->addr, sendbuf, send_size);
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/* response */
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command_params[1] = (struct tee_param) {
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.attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT,
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.u.memref = {
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.shm = shm,
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.size = MAX_RESPONSE_SIZE,
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.shm_offs = MAX_COMMAND_SIZE,
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},
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};
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rc = tee_invoke_func(context->tee_dev, &transceive_args, 4,
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command_params);
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if ((rc < 0) || (transceive_args.ret != 0)) {
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debug("%s:SUBMIT_COMMAND invoke error: 0x%x\n",
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__func__, transceive_args.ret);
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return (rc < 0) ? rc : transceive_args.ret;
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}
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resp_buf = command_params[1].u.memref.shm->addr +
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command_params[1].u.memref.shm_offs;
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resp_header = (struct tpm_output_header *)resp_buf;
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resp_len = be32_to_cpu(resp_header->length);
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/* sanity check resp_len*/
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if (resp_len < TPM_HEADER_SIZE) {
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debug("%s:tpm response header too small\n", __func__);
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return -EIO;
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}
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if (resp_len > MAX_RESPONSE_SIZE) {
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debug("%s:resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
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__func__, resp_len);
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return -EIO;
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}
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if (resp_len > *recv_len) {
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debug("%s:response length is bigger than receive buffer\n",
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__func__);
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return -EIO;
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}
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/* sanity checks look good, copy the response */
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memcpy(recvbuf, resp_buf, resp_len);
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*recv_len = resp_len;
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return 0;
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}
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static int ftpm_tee_open(struct udevice *dev)
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{
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struct ftpm_tee_private *context = dev_get_priv(dev);
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if (context->is_open)
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return -EBUSY;
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context->is_open = 1;
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return 0;
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}
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static int ftpm_tee_close(struct udevice *dev)
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{
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struct ftpm_tee_private *context = dev_get_priv(dev);
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if (context->is_open)
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context->is_open = 0;
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return 0;
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}
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static int ftpm_tee_desc(struct udevice *dev, char *buf, int size)
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{
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if (size < 32)
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return -ENOSPC;
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return snprintf(buf, size, "Microsoft OP-TEE fTPM");
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}
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static int ftpm_tee_match(struct tee_version_data *vers, const void *data)
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{
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debug("%s:vers->gen_caps =0x%x\n", __func__, vers->gen_caps);
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/*
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* Currently this driver only support GP Complaint OPTEE based fTPM TA
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*/
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return vers->gen_caps & TEE_GEN_CAP_GP;
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}
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static int ftpm_tee_probe(struct udevice *dev)
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{
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int rc;
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struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
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struct ftpm_tee_private *context = dev_get_priv(dev);
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struct tee_open_session_arg sess_arg;
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const struct tee_optee_ta_uuid uuid = TA_FTPM_UUID;
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memset(context, 0, sizeof(*context));
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/* Use the TPM v2 stack */
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priv->version = TPM_V2;
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priv->pcr_count = 24;
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priv->pcr_select_min = 3;
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/* Find TEE device */
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context->tee_dev = tee_find_device(NULL, ftpm_tee_match, NULL, NULL);
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if (!context->tee_dev) {
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debug("%s:tee_find_device failed\n", __func__);
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return -ENODEV;
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}
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/* Open a session with the fTPM TA */
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memset(&sess_arg, 0, sizeof(sess_arg));
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tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
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rc = tee_open_session(context->tee_dev, &sess_arg, 0, NULL);
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if ((rc < 0) || (sess_arg.ret != 0)) {
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debug("%s:tee_open_session failed, err=%x\n",
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__func__, sess_arg.ret);
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return -EIO;
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}
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context->session = sess_arg.session;
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/* Allocate dynamic shared memory with fTPM TA */
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rc = tee_shm_alloc(context->tee_dev,
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MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
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0, &context->shm);
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if (rc) {
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debug("%s:tee_shm_alloc failed with rc = %d\n", __func__, rc);
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goto out_shm_alloc;
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}
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return 0;
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out_shm_alloc:
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tee_close_session(context->tee_dev, context->session);
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return rc;
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}
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static int ftpm_tee_remove(struct udevice *dev)
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{
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struct ftpm_tee_private *context = dev_get_priv(dev);
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int rc;
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/* tee_pre_remove frees any leftover TEE shared memory */
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/* close the existing session with fTPM TA*/
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rc = tee_close_session(context->tee_dev, context->session);
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debug("%s: tee_close_session - rc =%d\n", __func__, rc);
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return 0;
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}
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static const struct tpm_ops ftpm_tee_ops = {
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.open = ftpm_tee_open,
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.close = ftpm_tee_close,
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.get_desc = ftpm_tee_desc,
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.xfer = ftpm_tee_transceive,
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};
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static const struct udevice_id ftpm_tee_ids[] = {
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{ .compatible = "microsoft,ftpm" },
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{ }
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};
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U_BOOT_DRIVER(ftpm_tee) = {
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.name = "ftpm_tee",
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.id = UCLASS_TPM,
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.of_match = ftpm_tee_ids,
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.ops = &ftpm_tee_ops,
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.probe = ftpm_tee_probe,
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.remove = ftpm_tee_remove,
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.flags = DM_FLAG_OS_PREPARE,
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.priv_auto_alloc_size = sizeof(struct ftpm_tee_private),
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};
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