drivers/char/tpm/tpm-chip.c

   1 /*
   2  * Copyright (C) 2004 IBM Corporation
   3  * Copyright (C) 2014 Intel Corporation
   4  *
   5  * Authors:
   6  * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
   7  * Leendert van Doorn <leendert@watson.ibm.com>
   8  * Dave Safford <safford@watson.ibm.com>
   9  * Reiner Sailer <sailer@watson.ibm.com>
  10  * Kylene Hall <kjhall@us.ibm.com>
  11  *
  12  * Maintained by: <tpmdd-devel@lists.sourceforge.net>
  13  *
  14  * TPM chip management routines.
  15  *
  16  * This program is free software; you can redistribute it and/or
  17  * modify it under the terms of the GNU General Public License as
  18  * published by the Free Software Foundation, version 2 of the
  19  * License.
  20  *
  21  */
  22
  23 #include <linux/poll.h>
  24 #include <linux/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/freezer.h>
  28 #include <linux/major.h>
  29 #include "tpm.h"
  30 #include "tpm_eventlog.h"
  31
  32 DEFINE_IDR(dev_nums_idr);
  33 static DEFINE_MUTEX(idr_lock);
  34
  35 struct class *tpm_class;
  36 dev_t tpm_devt;
  37
  38 /**
  39  * tpm_try_get_ops() - Get a ref to the tpm_chip
  40  * @chip: Chip to ref
  41  *
  42  * The caller must already have some kind of locking to ensure that chip is
  43  * valid. This function will lock the chip so that the ops member can be
  44  * accessed safely. The locking prevents tpm_chip_unregister from
  45  * completing, so it should not be held for long periods.
  46  *
  47  * Returns -ERRNO if the chip could not be got.
  48  */
  49 int tpm_try_get_ops(struct tpm_chip *chip)
  50 {
  51         int rc = -EIO;
  52
  53         get_device(&chip->dev);
  54
  55         down_read(&chip->ops_sem);
  56         if (!chip->ops)
  57                 goto out_lock;
  58
  59         return 0;
  60 out_lock:
  61         up_read(&chip->ops_sem);
  62         put_device(&chip->dev);
  63         return rc;
  64 }
  65 EXPORT_SYMBOL_GPL(tpm_try_get_ops);
  66
  67 /**
  68  * tpm_put_ops() - Release a ref to the tpm_chip
  69  * @chip: Chip to put
  70  *
  71  * This is the opposite pair to tpm_try_get_ops(). After this returns chip may
  72  * be kfree'd.
  73  */
  74 void tpm_put_ops(struct tpm_chip *chip)
  75 {
  76         up_read(&chip->ops_sem);
  77         put_device(&chip->dev);
  78 }
  79 EXPORT_SYMBOL_GPL(tpm_put_ops);
  80
  81 /**
  82  * tpm_chip_find_get() - return tpm_chip for a given chip number
  83  * @chip_num: id to find
  84  *
  85  * The return'd chip has been tpm_try_get_ops'd and must be released via
  86  * tpm_put_ops
  87  */
  88 struct tpm_chip *tpm_chip_find_get(int chip_num)
  89 {
  90         struct tpm_chip *chip, *res = NULL;
  91         int chip_prev;
  92
  93         mutex_lock(&idr_lock);
  94
  95         if (chip_num == TPM_ANY_NUM) {
  96                 chip_num = 0;
  97                 do {
  98                         chip_prev = chip_num;
  99                         chip = idr_get_next(&dev_nums_idr, &chip_num);
 100                         if (chip && !tpm_try_get_ops(chip)) {
 101                                 res = chip;
 102                                 break;
 103                         }
 104                 } while (chip_prev != chip_num);
 105         } else {
 106                 chip = idr_find(&dev_nums_idr, chip_num);
 107                 if (chip && !tpm_try_get_ops(chip))
 108                         res = chip;
 109         }
 110
 111         mutex_unlock(&idr_lock);
 112
 113         return res;
 114 }
 115
 116 /**
 117  * tpm_dev_release() - free chip memory and the device number
 118  * @dev: the character device for the TPM chip
 119  *
 120  * This is used as the release function for the character device.
 121  */
 122 static void tpm_dev_release(struct device *dev)
 123 {
 124         struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
 125
 126         mutex_lock(&idr_lock);
 127         idr_remove(&dev_nums_idr, chip->dev_num);
 128         mutex_unlock(&idr_lock);
 129
 130         kfree(chip->log.bios_event_log);
 131         kfree(chip);
 132 }
 133
 134 /**
 135  * tpm_chip_alloc() - allocate a new struct tpm_chip instance
 136  * @pdev: device to which the chip is associated
 137  *        At this point pdev mst be initialized, but does not have to
 138  *        be registered
 139  * @ops: struct tpm_class_ops instance
 140  *
 141  * Allocates a new struct tpm_chip instance and assigns a free
 142  * device number for it. Must be paired with put_device(&chip->dev).
 143  */
 144 struct tpm_chip *tpm_chip_alloc(struct device *dev,
 145                                 const struct tpm_class_ops *ops)
 146 {
 147         struct tpm_chip *chip;
 148         int rc;
 149
 150         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 151         if (chip == NULL)
 152                 return ERR_PTR(-ENOMEM);
 153
 154         mutex_init(&chip->tpm_mutex);
 155         init_rwsem(&chip->ops_sem);
 156
 157         chip->ops = ops;
 158
 159         mutex_lock(&idr_lock);
 160         rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
 161         mutex_unlock(&idr_lock);
 162         if (rc < 0) {
 163                 dev_err(dev, "No available tpm device numbers\n");
 164                 kfree(chip);
 165                 return ERR_PTR(rc);
 166         }
 167         chip->dev_num = rc;
 168
 169         device_initialize(&chip->dev);
 170
 171         chip->dev.class = tpm_class;
 172         chip->dev.release = tpm_dev_release;
 173         chip->dev.parent = dev;
 174         chip->dev.groups = chip->groups;
 175
 176         if (chip->dev_num == 0)
 177                 chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
 178         else
 179                 chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
 180
 181         rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num);
 182         if (rc)
 183                 goto out;
 184
 185         if (!dev)
 186                 chip->flags |= TPM_CHIP_FLAG_VIRTUAL;
 187
 188         cdev_init(&chip->cdev, &tpm_fops);
 189         chip->cdev.owner = THIS_MODULE;
 190         chip->cdev.kobj.parent = &chip->dev.kobj;
 191
 192         return chip;
 193
 194 out:
 195         put_device(&chip->dev);
 196         return ERR_PTR(rc);
 197 }
 198 EXPORT_SYMBOL_GPL(tpm_chip_alloc);
 199
 200 /**
 201  * tpmm_chip_alloc() - allocate a new struct tpm_chip instance
 202  * @pdev: parent device to which the chip is associated
 203  * @ops: struct tpm_class_ops instance
 204  *
 205  * Same as tpm_chip_alloc except devm is used to do the put_device
 206  */
 207 struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
 208                                  const struct tpm_class_ops *ops)
 209 {
 210         struct tpm_chip *chip;
 211         int rc;
 212
 213         chip = tpm_chip_alloc(pdev, ops);
 214         if (IS_ERR(chip))
 215                 return chip;
 216
 217         rc = devm_add_action_or_reset(pdev,
 218                                       (void (*)(void *)) put_device,
 219                                       &chip->dev);
 220         if (rc)
 221                 return ERR_PTR(rc);
 222
 223         dev_set_drvdata(pdev, chip);
 224
 225         return chip;
 226 }
 227 EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
 228
 229 static int tpm_add_char_device(struct tpm_chip *chip)
 230 {
 231         int rc;
 232
 233         rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
 234         if (rc) {
 235                 dev_err(&chip->dev,
 236                         "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
 237                         dev_name(&chip->dev), MAJOR(chip->dev.devt),
 238                         MINOR(chip->dev.devt), rc);
 239
 240                 return rc;
 241         }
 242
 243         rc = device_add(&chip->dev);
 244         if (rc) {
 245                 dev_err(&chip->dev,
 246                         "unable to device_register() %s, major %d, minor %d, err=%d\n",
 247                         dev_name(&chip->dev), MAJOR(chip->dev.devt),
 248                         MINOR(chip->dev.devt), rc);
 249
 250                 cdev_del(&chip->cdev);
 251                 return rc;
 252         }
 253
 254         /* Make the chip available. */
 255         mutex_lock(&idr_lock);
 256         idr_replace(&dev_nums_idr, chip, chip->dev_num);
 257         mutex_unlock(&idr_lock);
 258
 259         return rc;
 260 }
 261
 262 static void tpm_del_char_device(struct tpm_chip *chip)
 263 {
 264         cdev_del(&chip->cdev);
 265         device_del(&chip->dev);
 266
 267         /* Make the chip unavailable. */
 268         mutex_lock(&idr_lock);
 269         idr_replace(&dev_nums_idr, NULL, chip->dev_num);
 270         mutex_unlock(&idr_lock);
 271
 272         /* Make the driver uncallable. */
 273         down_write(&chip->ops_sem);
 274         if (chip->flags & TPM_CHIP_FLAG_TPM2)
 275                 tpm2_shutdown(chip, TPM2_SU_CLEAR);
 276         chip->ops = NULL;
 277         up_write(&chip->ops_sem);
 278 }
 279
 280 static void tpm_del_legacy_sysfs(struct tpm_chip *chip)
 281 {
 282         struct attribute **i;
 283
 284         if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
 285                 return;
 286
 287         sysfs_remove_link(&chip->dev.parent->kobj, "ppi");
 288
 289         for (i = chip->groups[0]->attrs; *i != NULL; ++i)
 290                 sysfs_remove_link(&chip->dev.parent->kobj, (*i)->name);
 291 }
 292
 293 /* For compatibility with legacy sysfs paths we provide symlinks from the
 294  * parent dev directory to selected names within the tpm chip directory. Old
 295  * kernel versions created these files directly under the parent.
 296  */
 297 static int tpm_add_legacy_sysfs(struct tpm_chip *chip)
 298 {
 299         struct attribute **i;
 300         int rc;
 301
 302         if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
 303                 return 0;
 304
 305         rc = __compat_only_sysfs_link_entry_to_kobj(
 306                     &chip->dev.parent->kobj, &chip->dev.kobj, "ppi");
 307         if (rc && rc != -ENOENT)
 308                 return rc;
 309
 310         /* All the names from tpm-sysfs */
 311         for (i = chip->groups[0]->attrs; *i != NULL; ++i) {
 312                 rc = __compat_only_sysfs_link_entry_to_kobj(
 313                     &chip->dev.parent->kobj, &chip->dev.kobj, (*i)->name);
 314                 if (rc) {
 315                         tpm_del_legacy_sysfs(chip);
 316                         return rc;
 317                 }
 318         }
 319
 320         return 0;
 321 }
 322 /*
 323  * tpm_chip_register() - create a character device for the TPM chip
 324  * @chip: TPM chip to use.
 325  *
 326  * Creates a character device for the TPM chip and adds sysfs attributes for
 327  * the device. As the last step this function adds the chip to the list of TPM
 328  * chips available for in-kernel use.
 329  *
 330  * This function should be only called after the chip initialization is
 331  * complete.
 332  */
 333 int tpm_chip_register(struct tpm_chip *chip)
 334 {
 335         int rc;
 336
 337         if (chip->ops->flags & TPM_OPS_AUTO_STARTUP) {
 338                 if (chip->flags & TPM_CHIP_FLAG_TPM2)
 339                         rc = tpm2_auto_startup(chip);
 340                 else
 341                         rc = tpm1_auto_startup(chip);
 342                 if (rc)
 343                         return rc;
 344         }
 345
 346         tpm_sysfs_add_device(chip);
 347
 348         rc = tpm_bios_log_setup(chip);
 349         if (rc != 0 && rc != -ENODEV)
 350                 return rc;
 351
 352         tpm_add_ppi(chip);
 353
 354         rc = tpm_add_char_device(chip);
 355         if (rc) {
 356                 tpm_bios_log_teardown(chip);
 357                 return rc;
 358         }
 359
 360         rc = tpm_add_legacy_sysfs(chip);
 361         if (rc) {
 362                 tpm_chip_unregister(chip);
 363                 return rc;
 364         }
 365
 366         return 0;
 367 }
 368 EXPORT_SYMBOL_GPL(tpm_chip_register);
 369
 370 /*
 371  * tpm_chip_unregister() - release the TPM driver
 372  * @chip: TPM chip to use.
 373  *
 374  * Takes the chip first away from the list of available TPM chips and then
 375  * cleans up all the resources reserved by tpm_chip_register().
 376  *
 377  * Once this function returns the driver call backs in 'op's will not be
 378  * running and will no longer start.
 379  *
 380  * NOTE: This function should be only called before deinitializing chip
 381  * resources.
 382  */
 383 void tpm_chip_unregister(struct tpm_chip *chip)
 384 {
 385         tpm_del_legacy_sysfs(chip);
 386         tpm_bios_log_teardown(chip);
 387         tpm_del_char_device(chip);
 388 }
 389 EXPORT_SYMBOL_GPL(tpm_chip_unregister);