1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) Microsoft Corporation 4 * 5 * Implements a firmware TPM as described here: 6 * https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/ 7 * 8 * A reference implementation is available here: 9 * https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM 10 */ 11 12 #include <linux/acpi.h> 13 #include <linux/of.h> 14 #include <linux/of_platform.h> 15 #include <linux/platform_device.h> 16 #include <linux/tee_drv.h> 17 #include <linux/tpm.h> 18 #include <linux/uuid.h> 19 20 #include "tpm.h" 21 #include "tpm_ftpm_tee.h" 22 23 /* 24 * TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896 25 * 26 * Randomly generated, and must correspond to the GUID on the TA side. 27 * Defined here in the reference implementation: 28 * https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42 29 */ 30 static const uuid_t ftpm_ta_uuid = 31 UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4, 32 0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96); 33 34 /** 35 * ftpm_tee_tpm_op_recv() - retrieve fTPM response. 36 * @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h. 37 * @buf: the buffer to store data. 38 * @count: the number of bytes to read. 39 * 40 * Return: 41 * In case of success the number of bytes received. 42 * On failure, -errno. 43 */ 44 static int ftpm_tee_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count) 45 { 46 struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent); 47 size_t len; 48 49 len = pvt_data->resp_len; 50 if (count < len) { 51 dev_err(&chip->dev, 52 "%s: Invalid size in recv: count=%zd, resp_len=%zd\n", 53 __func__, count, len); 54 return -EIO; 55 } 56 57 memcpy(buf, pvt_data->resp_buf, len); 58 pvt_data->resp_len = 0; 59 60 return len; 61 } 62 63 /** 64 * ftpm_tee_tpm_op_send() - send TPM commands through the TEE shared memory. 65 * @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h 66 * @buf: the buffer to send. 67 * @len: the number of bytes to send. 68 * 69 * Return: 70 * In case of success, returns 0. 71 * On failure, -errno 72 */ 73 static int ftpm_tee_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t len) 74 { 75 struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent); 76 size_t resp_len; 77 int rc; 78 u8 *temp_buf; 79 struct tpm_header *resp_header; 80 struct tee_ioctl_invoke_arg transceive_args; 81 struct tee_param command_params[4]; 82 struct tee_shm *shm = pvt_data->shm; 83 84 if (len > MAX_COMMAND_SIZE) { 85 dev_err(&chip->dev, 86 "%s: len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n", 87 __func__, len); 88 return -EIO; 89 } 90 91 memset(&transceive_args, 0, sizeof(transceive_args)); 92 memset(command_params, 0, sizeof(command_params)); 93 pvt_data->resp_len = 0; 94 95 /* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */ 96 transceive_args = (struct tee_ioctl_invoke_arg) { 97 .func = FTPM_OPTEE_TA_SUBMIT_COMMAND, 98 .session = pvt_data->session, 99 .num_params = 4, 100 }; 101 102 /* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */ 103 command_params[0] = (struct tee_param) { 104 .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT, 105 .u.memref = { 106 .shm = shm, 107 .size = len, 108 .shm_offs = 0, 109 }, 110 }; 111 112 temp_buf = tee_shm_get_va(shm, 0); 113 if (IS_ERR(temp_buf)) { 114 dev_err(&chip->dev, "%s: tee_shm_get_va failed for transmit\n", 115 __func__); 116 return PTR_ERR(temp_buf); 117 } 118 memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE)); 119 memcpy(temp_buf, buf, len); 120 121 command_params[1] = (struct tee_param) { 122 .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT, 123 .u.memref = { 124 .shm = shm, 125 .size = MAX_RESPONSE_SIZE, 126 .shm_offs = MAX_COMMAND_SIZE, 127 }, 128 }; 129 130 rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args, 131 command_params); 132 if ((rc < 0) || (transceive_args.ret != 0)) { 133 dev_err(&chip->dev, "%s: SUBMIT_COMMAND invoke error: 0x%x\n", 134 __func__, transceive_args.ret); 135 return (rc < 0) ? rc : transceive_args.ret; 136 } 137 138 temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs); 139 if (IS_ERR(temp_buf)) { 140 dev_err(&chip->dev, "%s: tee_shm_get_va failed for receive\n", 141 __func__); 142 return PTR_ERR(temp_buf); 143 } 144 145 resp_header = (struct tpm_header *)temp_buf; 146 resp_len = be32_to_cpu(resp_header->length); 147 148 /* sanity check resp_len */ 149 if (resp_len < TPM_HEADER_SIZE) { 150 dev_err(&chip->dev, "%s: tpm response header too small\n", 151 __func__); 152 return -EIO; 153 } 154 if (resp_len > MAX_RESPONSE_SIZE) { 155 dev_err(&chip->dev, 156 "%s: resp_len=%zd exceeds MAX_RESPONSE_SIZE\n", 157 __func__, resp_len); 158 return -EIO; 159 } 160 161 /* sanity checks look good, cache the response */ 162 memcpy(pvt_data->resp_buf, temp_buf, resp_len); 163 pvt_data->resp_len = resp_len; 164 165 return 0; 166 } 167 168 static void ftpm_tee_tpm_op_cancel(struct tpm_chip *chip) 169 { 170 /* not supported */ 171 } 172 173 static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip) 174 { 175 return 0; 176 } 177 178 static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status) 179 { 180 return 0; 181 } 182 183 static const struct tpm_class_ops ftpm_tee_tpm_ops = { 184 .flags = TPM_OPS_AUTO_STARTUP, 185 .recv = ftpm_tee_tpm_op_recv, 186 .send = ftpm_tee_tpm_op_send, 187 .cancel = ftpm_tee_tpm_op_cancel, 188 .status = ftpm_tee_tpm_op_status, 189 .req_complete_mask = 0, 190 .req_complete_val = 0, 191 .req_canceled = ftpm_tee_tpm_req_canceled, 192 }; 193 194 /* 195 * Check whether this driver supports the fTPM TA in the TEE instance 196 * represented by the params (ver/data) to this function. 197 */ 198 static int ftpm_tee_match(struct tee_ioctl_version_data *ver, const void *data) 199 { 200 /* 201 * Currently this driver only support GP Complaint OPTEE based fTPM TA 202 */ 203 if ((ver->impl_id == TEE_IMPL_ID_OPTEE) && 204 (ver->gen_caps & TEE_GEN_CAP_GP)) 205 return 1; 206 else 207 return 0; 208 } 209 210 /** 211 * ftpm_tee_probe() - initialize the fTPM 212 * @pdev: the platform_device description. 213 * 214 * Return: 215 * On success, 0. On failure, -errno. 216 */ 217 static int ftpm_tee_probe(struct platform_device *pdev) 218 { 219 int rc; 220 struct tpm_chip *chip; 221 struct device *dev = &pdev->dev; 222 struct ftpm_tee_private *pvt_data = NULL; 223 struct tee_ioctl_open_session_arg sess_arg; 224 225 pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private), 226 GFP_KERNEL); 227 if (!pvt_data) 228 return -ENOMEM; 229 230 dev_set_drvdata(dev, pvt_data); 231 232 /* Open context with TEE driver */ 233 pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL, 234 NULL); 235 if (IS_ERR(pvt_data->ctx)) { 236 if (PTR_ERR(pvt_data->ctx) == -ENOENT) 237 return -EPROBE_DEFER; 238 dev_err(dev, "%s: tee_client_open_context failed\n", __func__); 239 return PTR_ERR(pvt_data->ctx); 240 } 241 242 /* Open a session with fTPM TA */ 243 memset(&sess_arg, 0, sizeof(sess_arg)); 244 memcpy(sess_arg.uuid, ftpm_ta_uuid.b, TEE_IOCTL_UUID_LEN); 245 sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC; 246 sess_arg.num_params = 0; 247 248 rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL); 249 if ((rc < 0) || (sess_arg.ret != 0)) { 250 dev_err(dev, "%s: tee_client_open_session failed, err=%x\n", 251 __func__, sess_arg.ret); 252 rc = -EINVAL; 253 goto out_tee_session; 254 } 255 pvt_data->session = sess_arg.session; 256 257 /* Allocate dynamic shared memory with fTPM TA */ 258 pvt_data->shm = tee_shm_alloc(pvt_data->ctx, 259 MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE, 260 TEE_SHM_MAPPED | TEE_SHM_DMA_BUF); 261 if (IS_ERR(pvt_data->shm)) { 262 dev_err(dev, "%s: tee_shm_alloc failed\n", __func__); 263 rc = -ENOMEM; 264 goto out_shm_alloc; 265 } 266 267 /* Allocate new struct tpm_chip instance */ 268 chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops); 269 if (IS_ERR(chip)) { 270 dev_err(dev, "%s: tpm_chip_alloc failed\n", __func__); 271 rc = PTR_ERR(chip); 272 goto out_chip_alloc; 273 } 274 275 pvt_data->chip = chip; 276 pvt_data->chip->flags |= TPM_CHIP_FLAG_TPM2; 277 278 /* Create a character device for the fTPM */ 279 rc = tpm_chip_register(pvt_data->chip); 280 if (rc) { 281 dev_err(dev, "%s: tpm_chip_register failed with rc=%d\n", 282 __func__, rc); 283 goto out_chip; 284 } 285 286 return 0; 287 288 out_chip: 289 put_device(&pvt_data->chip->dev); 290 out_chip_alloc: 291 tee_shm_free(pvt_data->shm); 292 out_shm_alloc: 293 tee_client_close_session(pvt_data->ctx, pvt_data->session); 294 out_tee_session: 295 tee_client_close_context(pvt_data->ctx); 296 297 return rc; 298 } 299 300 /** 301 * ftpm_tee_remove() - remove the TPM device 302 * @pdev: the platform_device description. 303 * 304 * Return: 305 * 0 always. 306 */ 307 static int ftpm_tee_remove(struct platform_device *pdev) 308 { 309 struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev); 310 311 /* Release the chip */ 312 tpm_chip_unregister(pvt_data->chip); 313 314 /* frees chip */ 315 put_device(&pvt_data->chip->dev); 316 317 /* Free the shared memory pool */ 318 tee_shm_free(pvt_data->shm); 319 320 /* close the existing session with fTPM TA*/ 321 tee_client_close_session(pvt_data->ctx, pvt_data->session); 322 323 /* close the context with TEE driver */ 324 tee_client_close_context(pvt_data->ctx); 325 326 /* memory allocated with devm_kzalloc() is freed automatically */ 327 328 return 0; 329 } 330 331 /** 332 * ftpm_tee_shutdown() - shutdown the TPM device 333 * @pdev: the platform_device description. 334 */ 335 static void ftpm_tee_shutdown(struct platform_device *pdev) 336 { 337 struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev); 338 339 tee_shm_free(pvt_data->shm); 340 tee_client_close_session(pvt_data->ctx, pvt_data->session); 341 tee_client_close_context(pvt_data->ctx); 342 } 343 344 static const struct of_device_id of_ftpm_tee_ids[] = { 345 { .compatible = "microsoft,ftpm" }, 346 { } 347 }; 348 MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids); 349 350 static struct platform_driver ftpm_tee_driver = { 351 .driver = { 352 .name = "ftpm-tee", 353 .of_match_table = of_match_ptr(of_ftpm_tee_ids), 354 }, 355 .probe = ftpm_tee_probe, 356 .remove = ftpm_tee_remove, 357 .shutdown = ftpm_tee_shutdown, 358 }; 359 360 module_platform_driver(ftpm_tee_driver); 361 362 MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>"); 363 MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE"); 364 MODULE_LICENSE("GPL v2"); 365