drivers/tpm/tpm2_ftpm_tee.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) Microsoft Corporation
   4  *
   5  * Authors:
   6  * Thirupathaiah Annapureddy <thiruan@microsoft.com>
   7  *
   8  * Description:
   9  * Device Driver for a firmware TPM as described here:
  10  * https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
  11  *
  12  * A reference implementation is available here:
  13  * https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
  14  */
  15
  16 #include <common.h>
  17 #include <dm.h>
  18 #include <tpm-v2.h>
  19 #include <tee.h>
  20
  21 #include "tpm_tis.h"
  22 #include "tpm2_ftpm_tee.h"
  23
  24 /**
  25  * ftpm_tee_transceive() - send fTPM commands and retrieve fTPM response.
  26  * @sendbuf - address of the data to send, byte by byte
  27  * @send_size - length of the data to send
  28  * @recvbuf - address where to read the response, byte by byte.
  29  * @recv_len - pointer to the size of buffer
  30  *
  31  * Return:
  32  *      In case of success, returns 0.
  33  *      On failure, -errno
  34  */
  35 static int ftpm_tee_transceive(struct udevice *dev, const u8 *sendbuf,
  36                                 size_t send_size, u8 *recvbuf,
  37                                 size_t *recv_len)
  38 {
  39         struct ftpm_tee_private *context = dev_get_priv(dev);
  40         int rc = 0;
  41         size_t resp_len;
  42         u8 *resp_buf;
  43         struct tpm_output_header *resp_header;
  44         struct tee_invoke_arg transceive_args;
  45         struct tee_param command_params[4];
  46         struct tee_shm *shm;
  47
  48         if (send_size > MAX_COMMAND_SIZE) {
  49                 debug("%s:send_size=%zd exceeds MAX_COMMAND_SIZE\n",
  50                         __func__, send_size);
  51                 return -EIO;
  52         }
  53
  54         shm = context->shm;
  55         memset(&transceive_args, 0, sizeof(transceive_args));
  56         memset(command_params, 0, sizeof(command_params));
  57
  58         /* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
  59         transceive_args = (struct tee_invoke_arg) {
  60                 .func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
  61                 .session = context->session,
  62         };
  63
  64         /* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
  65         /* request */
  66         command_params[0] = (struct tee_param) {
  67                 .attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
  68                 .u.memref = {
  69                         .shm = shm,
  70                         .size = send_size,
  71                         .shm_offs = 0,
  72                 },
  73         };
  74         memset(command_params[0].u.memref.shm->addr, 0,
  75                 (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
  76         memcpy(command_params[0].u.memref.shm->addr, sendbuf, send_size);
  77
  78         /* response */
  79         command_params[1] = (struct tee_param) {
  80                 .attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT,
  81                 .u.memref = {
  82                         .shm = shm,
  83                         .size = MAX_RESPONSE_SIZE,
  84                         .shm_offs = MAX_COMMAND_SIZE,
  85                 },
  86         };
  87
  88         rc = tee_invoke_func(context->tee_dev, &transceive_args, 4,
  89                                 command_params);
  90         if ((rc < 0) || (transceive_args.ret != 0)) {
  91                 debug("%s:SUBMIT_COMMAND invoke error: 0x%x\n",
  92                         __func__, transceive_args.ret);
  93                 return (rc < 0) ? rc : transceive_args.ret;
  94         }
  95
  96         resp_buf = command_params[1].u.memref.shm->addr +
  97                 command_params[1].u.memref.shm_offs;
  98         resp_header = (struct tpm_output_header *)resp_buf;
  99         resp_len = be32_to_cpu(resp_header->length);
 100
 101         /* sanity check resp_len*/
 102         if (resp_len < TPM_HEADER_SIZE) {
 103                 debug("%s:tpm response header too small\n", __func__);
 104                 return -EIO;
 105         }
 106         if (resp_len > MAX_RESPONSE_SIZE) {
 107                 debug("%s:resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
 108                         __func__, resp_len);
 109                 return -EIO;
 110         }
 111         if (resp_len > *recv_len) {
 112                 debug("%s:response length is bigger than receive buffer\n",
 113                         __func__);
 114                 return -EIO;
 115         }
 116
 117         /* sanity checks look good, copy the response */
 118         memcpy(recvbuf,  resp_buf,  resp_len);
 119         *recv_len  = resp_len;
 120
 121         return 0;
 122 }
 123
 124 static int ftpm_tee_open(struct udevice *dev)
 125 {
 126         struct ftpm_tee_private *context = dev_get_priv(dev);
 127
 128         if (context->is_open)
 129                 return -EBUSY;
 130
 131         context->is_open = 1;
 132
 133         return 0;
 134 }
 135
 136 static int ftpm_tee_close(struct udevice *dev)
 137 {
 138         struct ftpm_tee_private *context = dev_get_priv(dev);
 139
 140         if (context->is_open)
 141                 context->is_open = 0;
 142
 143         return 0;
 144 }
 145
 146 static int ftpm_tee_desc(struct udevice *dev, char *buf, int size)
 147 {
 148         if (size < 32)
 149                 return -ENOSPC;
 150
 151         return snprintf(buf, size, "Microsoft OP-TEE fTPM");
 152 }
 153
 154 static int ftpm_tee_match(struct tee_version_data *vers, const void *data)
 155 {
 156         debug("%s:vers->gen_caps =0x%x\n", __func__, vers->gen_caps);
 157
 158         /*
 159          * Currently this driver only support GP Complaint OPTEE based fTPM TA
 160          */
 161         return vers->gen_caps & TEE_GEN_CAP_GP;
 162 }
 163
 164 static int ftpm_tee_probe(struct udevice *dev)
 165 {
 166         int rc;
 167         struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
 168         struct ftpm_tee_private *context = dev_get_priv(dev);
 169         struct tee_open_session_arg sess_arg;
 170         const struct tee_optee_ta_uuid uuid = TA_FTPM_UUID;
 171
 172         memset(context, 0, sizeof(*context));
 173
 174         /* Use the TPM v2 stack */
 175         priv->version = TPM_V2;
 176         priv->pcr_count = 24;
 177         priv->pcr_select_min = 3;
 178
 179         /* Find TEE device */
 180         context->tee_dev = tee_find_device(NULL, ftpm_tee_match, NULL, NULL);
 181         if (!context->tee_dev) {
 182                 debug("%s:tee_find_device failed\n", __func__);
 183                 return -ENODEV;
 184         }
 185
 186         /* Open a session with the fTPM TA */
 187         memset(&sess_arg, 0, sizeof(sess_arg));
 188         tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
 189
 190         rc = tee_open_session(context->tee_dev, &sess_arg, 0, NULL);
 191         if ((rc < 0) || (sess_arg.ret != 0)) {
 192                 debug("%s:tee_open_session failed, err=%x\n",
 193                         __func__, sess_arg.ret);
 194                 return -EIO;
 195         }
 196         context->session = sess_arg.session;
 197
 198         /* Allocate dynamic shared memory with fTPM TA */
 199         rc = tee_shm_alloc(context->tee_dev,
 200                         MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
 201                         0, &context->shm);
 202         if (rc) {
 203                 debug("%s:tee_shm_alloc failed with rc = %d\n", __func__, rc);
 204                 goto out_shm_alloc;
 205         }
 206
 207         return 0;
 208
 209 out_shm_alloc:
 210         tee_close_session(context->tee_dev, context->session);
 211
 212         return rc;
 213 }
 214
 215 static int ftpm_tee_remove(struct udevice *dev)
 216 {
 217         struct ftpm_tee_private *context = dev_get_priv(dev);
 218         int rc;
 219
 220         /* tee_pre_remove frees any leftover TEE shared memory */
 221
 222         /* close the existing session with fTPM TA*/
 223         rc = tee_close_session(context->tee_dev, context->session);
 224         debug("%s: tee_close_session - rc =%d\n", __func__, rc);
 225
 226         return 0;
 227 }
 228
 229 static const struct tpm_ops ftpm_tee_ops = {
 230         .open           = ftpm_tee_open,
 231         .close          = ftpm_tee_close,
 232         .get_desc       = ftpm_tee_desc,
 233         .xfer           = ftpm_tee_transceive,
 234 };
 235
 236 static const struct udevice_id ftpm_tee_ids[] = {
 237         { .compatible = "microsoft,ftpm" },
 238         { }
 239 };
 240
 241 U_BOOT_DRIVER(ftpm_tee) = {
 242         .name   = "ftpm_tee",
 243         .id     = UCLASS_TPM,
 244         .of_match = ftpm_tee_ids,
 245         .ops    = &ftpm_tee_ops,
 246         .probe  = ftpm_tee_probe,
 247         .remove = ftpm_tee_remove,
 248         .flags  = DM_FLAG_OS_PREPARE,
 249         .priv_auto_alloc_size = sizeof(struct ftpm_tee_private),
 250 };