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/platform_device.h> 15 #include <linux/tee_drv.h> 16 #include <linux/tpm.h> 17 #include <linux/uuid.h> 18 19 #include "tpm.h" 20 #include "tpm_ftpm_tee.h" 21 22 /* 23 * TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896 24 * 25 * Randomly generated, and must correspond to the GUID on the TA side. 26 * Defined here in the reference implementation: 27 * https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42 28 */ 29 static const uuid_t ftpm_ta_uuid = 30 UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4, 31 0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96); 32 33 /** 34 * ftpm_tee_tpm_op_recv() - retrieve fTPM response. 35 * @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h. 36 * @buf: the buffer to store data. 37 * @count: the number of bytes to read. 38 * 39 * Return: 40 * In case of success the number of bytes received. 41 * On failure, -errno. 42 */ 43 static int ftpm_tee_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count) 44 { 45 struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent); 46 size_t len; 47 48 len = pvt_data->resp_len; 49 if (count < len) { 50 dev_err(&chip->dev, 51 "%s: Invalid size in recv: count=%zd, resp_len=%zd\n", 52 __func__, count, len); 53 return -EIO; 54 } 55 56 memcpy(buf, pvt_data->resp_buf, len); 57 pvt_data->resp_len = 0; 58 59 return len; 60 } 61 62 /** 63 * ftpm_tee_tpm_op_send() - send TPM commands through the TEE shared memory. 64 * @chip: the tpm_chip description as specified in driver/char/tpm/tpm.h 65 * @buf: the buffer to send. 66 * @len: the number of bytes to send. 67 * 68 * Return: 69 * In case of success, returns 0. 70 * On failure, -errno 71 */ 72 static int ftpm_tee_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t len) 73 { 74 struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent); 75 size_t resp_len; 76 int rc; 77 u8 *temp_buf; 78 struct tpm_header *resp_header; 79 struct tee_ioctl_invoke_arg transceive_args; 80 struct tee_param command_params[4]; 81 struct tee_shm *shm = pvt_data->shm; 82 83 if (len > MAX_COMMAND_SIZE) { 84 dev_err(&chip->dev, 85 "%s: len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n", 86 __func__, len); 87 return -EIO; 88 } 89 90 memset(&transceive_args, 0, sizeof(transceive_args)); 91 memset(command_params, 0, sizeof(command_params)); 92 pvt_data->resp_len = 0; 93 94 /* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */ 95 transceive_args = (struct tee_ioctl_invoke_arg) { 96 .func = FTPM_OPTEE_TA_SUBMIT_COMMAND, 97 .session = pvt_data->session, 98 .num_params = 4, 99 }; 100 101 /* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */ 102 command_params[0] = (struct tee_param) { 103 .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT, 104 .u.memref = { 105 .shm = shm, 106 .size = len, 107 .shm_offs = 0, 108 }, 109 }; 110 111 temp_buf = tee_shm_get_va(shm, 0); 112 if (IS_ERR(temp_buf)) { 113 dev_err(&chip->dev, "%s: tee_shm_get_va failed for transmit\n", 114 __func__); 115 return PTR_ERR(temp_buf); 116 } 117 memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE)); 118 memcpy(temp_buf, buf, len); 119 120 command_params[1] = (struct tee_param) { 121 .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT, 122 .u.memref = { 123 .shm = shm, 124 .size = MAX_RESPONSE_SIZE, 125 .shm_offs = MAX_COMMAND_SIZE, 126 }, 127 }; 128 129 rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args, 130 command_params); 131 if ((rc < 0) || (transceive_args.ret != 0)) { 132 dev_err(&chip->dev, "%s: SUBMIT_COMMAND invoke error: 0x%x\n", 133 __func__, transceive_args.ret); 134 return (rc < 0) ? rc : transceive_args.ret; 135 } 136 137 temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs); 138 if (IS_ERR(temp_buf)) { 139 dev_err(&chip->dev, "%s: tee_shm_get_va failed for receive\n", 140 __func__); 141 return PTR_ERR(temp_buf); 142 } 143 144 resp_header = (struct tpm_header *)temp_buf; 145 resp_len = be32_to_cpu(resp_header->length); 146 147 /* sanity check resp_len */ 148 if (resp_len < TPM_HEADER_SIZE) { 149 dev_err(&chip->dev, "%s: tpm response header too small\n", 150 __func__); 151 return -EIO; 152 } 153 if (resp_len > MAX_RESPONSE_SIZE) { 154 dev_err(&chip->dev, 155 "%s: resp_len=%zd exceeds MAX_RESPONSE_SIZE\n", 156 __func__, resp_len); 157 return -EIO; 158 } 159 160 /* sanity checks look good, cache the response */ 161 memcpy(pvt_data->resp_buf, temp_buf, resp_len); 162 pvt_data->resp_len = resp_len; 163 164 return 0; 165 } 166 167 static const struct tpm_class_ops ftpm_tee_tpm_ops = { 168 .flags = TPM_OPS_AUTO_STARTUP, 169 .recv = ftpm_tee_tpm_op_recv, 170 .send = ftpm_tee_tpm_op_send, 171 }; 172 173 /* 174 * Check whether this driver supports the fTPM TA in the TEE instance 175 * represented by the params (ver/data) to this function. 176 */ 177 static int ftpm_tee_match(struct tee_ioctl_version_data *ver, const void *data) 178 { 179 /* 180 * Currently this driver only support GP Complaint OPTEE based fTPM TA 181 */ 182 if ((ver->impl_id == TEE_IMPL_ID_OPTEE) && 183 (ver->gen_caps & TEE_GEN_CAP_GP)) 184 return 1; 185 else 186 return 0; 187 } 188 189 /** 190 * ftpm_tee_probe() - initialize the fTPM 191 * @dev: the device description. 192 * 193 * Return: 194 * On success, 0. On failure, -errno. 195 */ 196 static int ftpm_tee_probe(struct device *dev) 197 { 198 int rc; 199 struct tpm_chip *chip; 200 struct ftpm_tee_private *pvt_data = NULL; 201 struct tee_ioctl_open_session_arg sess_arg; 202 203 pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private), 204 GFP_KERNEL); 205 if (!pvt_data) 206 return -ENOMEM; 207 208 dev_set_drvdata(dev, pvt_data); 209 210 /* Open context with TEE driver */ 211 pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL, 212 NULL); 213 if (IS_ERR(pvt_data->ctx)) { 214 if (PTR_ERR(pvt_data->ctx) == -ENOENT) 215 return -EPROBE_DEFER; 216 dev_err(dev, "%s: tee_client_open_context failed\n", __func__); 217 return PTR_ERR(pvt_data->ctx); 218 } 219 220 /* Open a session with fTPM TA */ 221 memset(&sess_arg, 0, sizeof(sess_arg)); 222 export_uuid(sess_arg.uuid, &ftpm_ta_uuid); 223 sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC; 224 sess_arg.num_params = 0; 225 226 rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL); 227 if ((rc < 0) || (sess_arg.ret != 0)) { 228 dev_err(dev, "%s: tee_client_open_session failed, err=%x\n", 229 __func__, sess_arg.ret); 230 rc = -EINVAL; 231 goto out_tee_session; 232 } 233 pvt_data->session = sess_arg.session; 234 235 /* Allocate dynamic shared memory with fTPM TA */ 236 pvt_data->shm = tee_shm_alloc_kernel_buf(pvt_data->ctx, 237 MAX_COMMAND_SIZE + 238 MAX_RESPONSE_SIZE); 239 if (IS_ERR(pvt_data->shm)) { 240 dev_err(dev, "%s: tee_shm_alloc_kernel_buf failed\n", __func__); 241 rc = -ENOMEM; 242 goto out_shm_alloc; 243 } 244 245 /* Allocate new struct tpm_chip instance */ 246 chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops); 247 if (IS_ERR(chip)) { 248 dev_err(dev, "%s: tpm_chip_alloc failed\n", __func__); 249 rc = PTR_ERR(chip); 250 goto out_chip_alloc; 251 } 252 253 pvt_data->chip = chip; 254 pvt_data->chip->flags |= TPM_CHIP_FLAG_TPM2; 255 256 /* Create a character device for the fTPM */ 257 rc = tpm_chip_register(pvt_data->chip); 258 if (rc) { 259 dev_err(dev, "%s: tpm_chip_register failed with rc=%d\n", 260 __func__, rc); 261 goto out_chip; 262 } 263 264 return 0; 265 266 out_chip: 267 put_device(&pvt_data->chip->dev); 268 out_chip_alloc: 269 tee_shm_free(pvt_data->shm); 270 out_shm_alloc: 271 tee_client_close_session(pvt_data->ctx, pvt_data->session); 272 out_tee_session: 273 tee_client_close_context(pvt_data->ctx); 274 275 return rc; 276 } 277 278 static int ftpm_plat_tee_probe(struct platform_device *pdev) 279 { 280 struct device *dev = &pdev->dev; 281 282 return ftpm_tee_probe(dev); 283 } 284 285 /** 286 * ftpm_tee_remove() - remove the TPM device 287 * @dev: the device description. 288 * 289 * Return: 290 * 0 always. 291 */ 292 static int ftpm_tee_remove(struct device *dev) 293 { 294 struct ftpm_tee_private *pvt_data = dev_get_drvdata(dev); 295 296 /* Release the chip */ 297 tpm_chip_unregister(pvt_data->chip); 298 299 /* frees chip */ 300 put_device(&pvt_data->chip->dev); 301 302 /* Free the shared memory pool */ 303 tee_shm_free(pvt_data->shm); 304 305 /* close the existing session with fTPM TA*/ 306 tee_client_close_session(pvt_data->ctx, pvt_data->session); 307 308 /* close the context with TEE driver */ 309 tee_client_close_context(pvt_data->ctx); 310 311 /* memory allocated with devm_kzalloc() is freed automatically */ 312 313 return 0; 314 } 315 316 static void ftpm_plat_tee_remove(struct platform_device *pdev) 317 { 318 struct device *dev = &pdev->dev; 319 320 ftpm_tee_remove(dev); 321 } 322 323 /** 324 * ftpm_plat_tee_shutdown() - shutdown the TPM device 325 * @pdev: the platform_device description. 326 */ 327 static void ftpm_plat_tee_shutdown(struct platform_device *pdev) 328 { 329 struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev); 330 331 tee_shm_free(pvt_data->shm); 332 tee_client_close_session(pvt_data->ctx, pvt_data->session); 333 tee_client_close_context(pvt_data->ctx); 334 } 335 336 static const struct of_device_id of_ftpm_tee_ids[] = { 337 { .compatible = "microsoft,ftpm" }, 338 { } 339 }; 340 MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids); 341 342 static struct platform_driver ftpm_tee_plat_driver = { 343 .driver = { 344 .name = "ftpm-tee", 345 .of_match_table = of_ftpm_tee_ids, 346 }, 347 .shutdown = ftpm_plat_tee_shutdown, 348 .probe = ftpm_plat_tee_probe, 349 .remove = ftpm_plat_tee_remove, 350 }; 351 352 /* UUID of the fTPM TA */ 353 static const struct tee_client_device_id optee_ftpm_id_table[] = { 354 {UUID_INIT(0xbc50d971, 0xd4c9, 0x42c4, 355 0x82, 0xcb, 0x34, 0x3f, 0xb7, 0xf3, 0x78, 0x96)}, 356 {} 357 }; 358 359 MODULE_DEVICE_TABLE(tee, optee_ftpm_id_table); 360 361 static struct tee_client_driver ftpm_tee_driver = { 362 .id_table = optee_ftpm_id_table, 363 .driver = { 364 .name = "optee-ftpm", 365 .bus = &tee_bus_type, 366 .probe = ftpm_tee_probe, 367 .remove = ftpm_tee_remove, 368 }, 369 }; 370 371 static int __init ftpm_mod_init(void) 372 { 373 int rc; 374 375 rc = platform_driver_register(&ftpm_tee_plat_driver); 376 if (rc) 377 return rc; 378 379 rc = driver_register(&ftpm_tee_driver.driver); 380 if (rc) { 381 platform_driver_unregister(&ftpm_tee_plat_driver); 382 return rc; 383 } 384 385 return 0; 386 } 387 388 static void __exit ftpm_mod_exit(void) 389 { 390 platform_driver_unregister(&ftpm_tee_plat_driver); 391 driver_unregister(&ftpm_tee_driver.driver); 392 } 393 394 module_init(ftpm_mod_init); 395 module_exit(ftpm_mod_exit); 396 397 MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>"); 398 MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE"); 399 MODULE_LICENSE("GPL v2"); 400