drivers/nvdimm/security.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright(c) 2018 Intel Corporation. All rights reserved. */
   3
   4 #include <linux/module.h>
   5 #include <linux/device.h>
   6 #include <linux/ndctl.h>
   7 #include <linux/slab.h>
   8 #include <linux/io.h>
   9 #include <linux/mm.h>
  10 #include <linux/cred.h>
  11 #include <linux/key.h>
  12 #include <linux/key-type.h>
  13 #include <keys/user-type.h>
  14 #include <keys/encrypted-type.h>
  15 #include "nd-core.h"
  16 #include "nd.h"
  17
  18 #define NVDIMM_BASE_KEY         0
  19 #define NVDIMM_NEW_KEY          1
  20
  21 static bool key_revalidate = true;
  22 module_param(key_revalidate, bool, 0444);
  23 MODULE_PARM_DESC(key_revalidate, "Require key validation at init.");
  24
  25 static const char zero_key[NVDIMM_PASSPHRASE_LEN];
  26
  27 static void *key_data(struct key *key)
  28 {
  29         struct encrypted_key_payload *epayload = dereference_key_locked(key);
  30
  31         lockdep_assert_held_read(&key->sem);
  32
  33         return epayload->decrypted_data;
  34 }
  35
  36 static void nvdimm_put_key(struct key *key)
  37 {
  38         if (!key)
  39                 return;
  40
  41         up_read(&key->sem);
  42         key_put(key);
  43 }
  44
  45 /*
  46  * Retrieve kernel key for DIMM and request from user space if
  47  * necessary. Returns a key held for read and must be put by
  48  * nvdimm_put_key() before the usage goes out of scope.
  49  */
  50 static struct key *nvdimm_request_key(struct nvdimm *nvdimm)
  51 {
  52         struct key *key = NULL;
  53         static const char NVDIMM_PREFIX[] = "nvdimm:";
  54         char desc[NVDIMM_KEY_DESC_LEN + sizeof(NVDIMM_PREFIX)];
  55         struct device *dev = &nvdimm->dev;
  56
  57         sprintf(desc, "%s%s", NVDIMM_PREFIX, nvdimm->dimm_id);
  58         key = request_key(&key_type_encrypted, desc, "");
  59         if (IS_ERR(key)) {
  60                 if (PTR_ERR(key) == -ENOKEY)
  61                         dev_dbg(dev, "request_key() found no key\n");
  62                 else
  63                         dev_dbg(dev, "request_key() upcall failed\n");
  64                 key = NULL;
  65         } else {
  66                 struct encrypted_key_payload *epayload;
  67
  68                 down_read(&key->sem);
  69                 epayload = dereference_key_locked(key);
  70                 if (epayload->decrypted_datalen != NVDIMM_PASSPHRASE_LEN) {
  71                         up_read(&key->sem);
  72                         key_put(key);
  73                         key = NULL;
  74                 }
  75         }
  76
  77         return key;
  78 }
  79
  80 static const void *nvdimm_get_key_payload(struct nvdimm *nvdimm,
  81                 struct key **key)
  82 {
  83         *key = nvdimm_request_key(nvdimm);
  84         if (!*key)
  85                 return zero_key;
  86
  87         return key_data(*key);
  88 }
  89
  90 static struct key *nvdimm_lookup_user_key(struct nvdimm *nvdimm,
  91                 key_serial_t id, int subclass)
  92 {
  93         key_ref_t keyref;
  94         struct key *key;
  95         struct encrypted_key_payload *epayload;
  96         struct device *dev = &nvdimm->dev;
  97
  98         keyref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
  99         if (IS_ERR(keyref))
 100                 return NULL;
 101
 102         key = key_ref_to_ptr(keyref);
 103         if (key->type != &key_type_encrypted) {
 104                 key_put(key);
 105                 return NULL;
 106         }
 107
 108         dev_dbg(dev, "%s: key found: %#x\n", __func__, key_serial(key));
 109
 110         down_read_nested(&key->sem, subclass);
 111         epayload = dereference_key_locked(key);
 112         if (epayload->decrypted_datalen != NVDIMM_PASSPHRASE_LEN) {
 113                 up_read(&key->sem);
 114                 key_put(key);
 115                 key = NULL;
 116         }
 117         return key;
 118 }
 119
 120 static const void *nvdimm_get_user_key_payload(struct nvdimm *nvdimm,
 121                 key_serial_t id, int subclass, struct key **key)
 122 {
 123         *key = NULL;
 124         if (id == 0) {
 125                 if (subclass == NVDIMM_BASE_KEY)
 126                         return zero_key;
 127                 else
 128                         return NULL;
 129         }
 130
 131         *key = nvdimm_lookup_user_key(nvdimm, id, subclass);
 132         if (!*key)
 133                 return NULL;
 134
 135         return key_data(*key);
 136 }
 137
 138
 139 static int nvdimm_key_revalidate(struct nvdimm *nvdimm)
 140 {
 141         struct key *key;
 142         int rc;
 143         const void *data;
 144
 145         if (!nvdimm->sec.ops->change_key)
 146                 return -EOPNOTSUPP;
 147
 148         data = nvdimm_get_key_payload(nvdimm, &key);
 149
 150         /*
 151          * Send the same key to the hardware as new and old key to
 152          * verify that the key is good.
 153          */
 154         rc = nvdimm->sec.ops->change_key(nvdimm, data, data, NVDIMM_USER);
 155         if (rc < 0) {
 156                 nvdimm_put_key(key);
 157                 return rc;
 158         }
 159
 160         nvdimm_put_key(key);
 161         nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 162         return 0;
 163 }
 164
 165 static int __nvdimm_security_unlock(struct nvdimm *nvdimm)
 166 {
 167         struct device *dev = &nvdimm->dev;
 168         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
 169         struct key *key;
 170         const void *data;
 171         int rc;
 172
 173         /* The bus lock should be held at the top level of the call stack */
 174         lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
 175
 176         if (!nvdimm->sec.ops || !nvdimm->sec.ops->unlock
 177                         || !nvdimm->sec.flags)
 178                 return -EIO;
 179
 180         /* No need to go further if security is disabled */
 181         if (test_bit(NVDIMM_SECURITY_DISABLED, &nvdimm->sec.flags))
 182                 return 0;
 183
 184         if (test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags)) {
 185                 dev_dbg(dev, "Security operation in progress.\n");
 186                 return -EBUSY;
 187         }
 188
 189         /*
 190          * If the pre-OS has unlocked the DIMM, attempt to send the key
 191          * from request_key() to the hardware for verification.  Failure
 192          * to revalidate the key against the hardware results in a
 193          * freeze of the security configuration. I.e. if the OS does not
 194          * have the key, security is being managed pre-OS.
 195          */
 196         if (test_bit(NVDIMM_SECURITY_UNLOCKED, &nvdimm->sec.flags)) {
 197                 if (!key_revalidate)
 198                         return 0;
 199
 200                 return nvdimm_key_revalidate(nvdimm);
 201         } else
 202                 data = nvdimm_get_key_payload(nvdimm, &key);
 203
 204         rc = nvdimm->sec.ops->unlock(nvdimm, data);
 205         dev_dbg(dev, "key: %d unlock: %s\n", key_serial(key),
 206                         rc == 0 ? "success" : "fail");
 207
 208         nvdimm_put_key(key);
 209         nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 210         return rc;
 211 }
 212
 213 int nvdimm_security_unlock(struct device *dev)
 214 {
 215         struct nvdimm *nvdimm = to_nvdimm(dev);
 216         int rc;
 217
 218         nvdimm_bus_lock(dev);
 219         rc = __nvdimm_security_unlock(nvdimm);
 220         nvdimm_bus_unlock(dev);
 221         return rc;
 222 }
 223
 224 static int check_security_state(struct nvdimm *nvdimm)
 225 {
 226         struct device *dev = &nvdimm->dev;
 227
 228         if (test_bit(NVDIMM_SECURITY_FROZEN, &nvdimm->sec.flags)) {
 229                 dev_dbg(dev, "Incorrect security state: %#lx\n",
 230                                 nvdimm->sec.flags);
 231                 return -EIO;
 232         }
 233
 234         if (test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags)) {
 235                 dev_dbg(dev, "Security operation in progress.\n");
 236                 return -EBUSY;
 237         }
 238
 239         return 0;
 240 }
 241
 242 static int security_disable(struct nvdimm *nvdimm, unsigned int keyid)
 243 {
 244         struct device *dev = &nvdimm->dev;
 245         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
 246         struct key *key;
 247         int rc;
 248         const void *data;
 249
 250         /* The bus lock should be held at the top level of the call stack */
 251         lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
 252
 253         if (!nvdimm->sec.ops || !nvdimm->sec.ops->disable
 254                         || !nvdimm->sec.flags)
 255                 return -EOPNOTSUPP;
 256
 257         rc = check_security_state(nvdimm);
 258         if (rc)
 259                 return rc;
 260
 261         data = nvdimm_get_user_key_payload(nvdimm, keyid,
 262                         NVDIMM_BASE_KEY, &key);
 263         if (!data)
 264                 return -ENOKEY;
 265
 266         rc = nvdimm->sec.ops->disable(nvdimm, data);
 267         dev_dbg(dev, "key: %d disable: %s\n", key_serial(key),
 268                         rc == 0 ? "success" : "fail");
 269
 270         nvdimm_put_key(key);
 271         nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 272         return rc;
 273 }
 274
 275 static int security_update(struct nvdimm *nvdimm, unsigned int keyid,
 276                 unsigned int new_keyid,
 277                 enum nvdimm_passphrase_type pass_type)
 278 {
 279         struct device *dev = &nvdimm->dev;
 280         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
 281         struct key *key, *newkey;
 282         int rc;
 283         const void *data, *newdata;
 284
 285         /* The bus lock should be held at the top level of the call stack */
 286         lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
 287
 288         if (!nvdimm->sec.ops || !nvdimm->sec.ops->change_key
 289                         || !nvdimm->sec.flags)
 290                 return -EOPNOTSUPP;
 291
 292         rc = check_security_state(nvdimm);
 293         if (rc)
 294                 return rc;
 295
 296         data = nvdimm_get_user_key_payload(nvdimm, keyid,
 297                         NVDIMM_BASE_KEY, &key);
 298         if (!data)
 299                 return -ENOKEY;
 300
 301         newdata = nvdimm_get_user_key_payload(nvdimm, new_keyid,
 302                         NVDIMM_NEW_KEY, &newkey);
 303         if (!newdata) {
 304                 nvdimm_put_key(key);
 305                 return -ENOKEY;
 306         }
 307
 308         rc = nvdimm->sec.ops->change_key(nvdimm, data, newdata, pass_type);
 309         dev_dbg(dev, "key: %d %d update%s: %s\n",
 310                         key_serial(key), key_serial(newkey),
 311                         pass_type == NVDIMM_MASTER ? "(master)" : "(user)",
 312                         rc == 0 ? "success" : "fail");
 313
 314         nvdimm_put_key(newkey);
 315         nvdimm_put_key(key);
 316         if (pass_type == NVDIMM_MASTER)
 317                 nvdimm->sec.ext_flags = nvdimm_security_flags(nvdimm,
 318                                 NVDIMM_MASTER);
 319         else
 320                 nvdimm->sec.flags = nvdimm_security_flags(nvdimm,
 321                                 NVDIMM_USER);
 322         return rc;
 323 }
 324
 325 static int security_erase(struct nvdimm *nvdimm, unsigned int keyid,
 326                 enum nvdimm_passphrase_type pass_type)
 327 {
 328         struct device *dev = &nvdimm->dev;
 329         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
 330         struct key *key = NULL;
 331         int rc;
 332         const void *data;
 333
 334         /* The bus lock should be held at the top level of the call stack */
 335         lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
 336
 337         if (!nvdimm->sec.ops || !nvdimm->sec.ops->erase
 338                         || !nvdimm->sec.flags)
 339                 return -EOPNOTSUPP;
 340
 341         rc = check_security_state(nvdimm);
 342         if (rc)
 343                 return rc;
 344
 345         if (!test_bit(NVDIMM_SECURITY_UNLOCKED, &nvdimm->sec.ext_flags)
 346                         && pass_type == NVDIMM_MASTER) {
 347                 dev_dbg(dev,
 348                         "Attempt to secure erase in wrong master state.\n");
 349                 return -EOPNOTSUPP;
 350         }
 351
 352         data = nvdimm_get_user_key_payload(nvdimm, keyid,
 353                         NVDIMM_BASE_KEY, &key);
 354         if (!data)
 355                 return -ENOKEY;
 356
 357         rc = nvdimm->sec.ops->erase(nvdimm, data, pass_type);
 358         dev_dbg(dev, "key: %d erase%s: %s\n", key_serial(key),
 359                         pass_type == NVDIMM_MASTER ? "(master)" : "(user)",
 360                         rc == 0 ? "success" : "fail");
 361
 362         nvdimm_put_key(key);
 363         nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 364         return rc;
 365 }
 366
 367 static int security_overwrite(struct nvdimm *nvdimm, unsigned int keyid)
 368 {
 369         struct device *dev = &nvdimm->dev;
 370         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
 371         struct key *key = NULL;
 372         int rc;
 373         const void *data;
 374
 375         /* The bus lock should be held at the top level of the call stack */
 376         lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
 377
 378         if (!nvdimm->sec.ops || !nvdimm->sec.ops->overwrite
 379                         || !nvdimm->sec.flags)
 380                 return -EOPNOTSUPP;
 381
 382         rc = check_security_state(nvdimm);
 383         if (rc)
 384                 return rc;
 385
 386         data = nvdimm_get_user_key_payload(nvdimm, keyid,
 387                         NVDIMM_BASE_KEY, &key);
 388         if (!data)
 389                 return -ENOKEY;
 390
 391         rc = nvdimm->sec.ops->overwrite(nvdimm, data);
 392         dev_dbg(dev, "key: %d overwrite submission: %s\n", key_serial(key),
 393                         rc == 0 ? "success" : "fail");
 394
 395         nvdimm_put_key(key);
 396         if (rc == 0) {
 397                 set_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
 398                 set_bit(NDD_WORK_PENDING, &nvdimm->flags);
 399                 set_bit(NVDIMM_SECURITY_OVERWRITE, &nvdimm->sec.flags);
 400                 /*
 401                  * Make sure we don't lose device while doing overwrite
 402                  * query.
 403                  */
 404                 get_device(dev);
 405                 queue_delayed_work(system_wq, &nvdimm->dwork, 0);
 406         }
 407
 408         return rc;
 409 }
 410
 411 void __nvdimm_security_overwrite_query(struct nvdimm *nvdimm)
 412 {
 413         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nvdimm->dev);
 414         int rc;
 415         unsigned int tmo;
 416
 417         /* The bus lock should be held at the top level of the call stack */
 418         lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
 419
 420         /*
 421          * Abort and release device if we no longer have the overwrite
 422          * flag set. It means the work has been canceled.
 423          */
 424         if (!test_bit(NDD_WORK_PENDING, &nvdimm->flags))
 425                 return;
 426
 427         tmo = nvdimm->sec.overwrite_tmo;
 428
 429         if (!nvdimm->sec.ops || !nvdimm->sec.ops->query_overwrite
 430                         || !nvdimm->sec.flags)
 431                 return;
 432
 433         rc = nvdimm->sec.ops->query_overwrite(nvdimm);
 434         if (rc == -EBUSY) {
 435
 436                 /* setup delayed work again */
 437                 tmo += 10;
 438                 queue_delayed_work(system_wq, &nvdimm->dwork, tmo * HZ);
 439                 nvdimm->sec.overwrite_tmo = min(15U * 60U, tmo);
 440                 return;
 441         }
 442
 443         if (rc < 0)
 444                 dev_dbg(&nvdimm->dev, "overwrite failed\n");
 445         else
 446                 dev_dbg(&nvdimm->dev, "overwrite completed\n");
 447
 448         /*
 449          * Mark the overwrite work done and update dimm security flags,
 450          * then send a sysfs event notification to wake up userspace
 451          * poll threads to picked up the changed state.
 452          */
 453         nvdimm->sec.overwrite_tmo = 0;
 454         clear_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
 455         clear_bit(NDD_WORK_PENDING, &nvdimm->flags);
 456         nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 457         nvdimm->sec.ext_flags = nvdimm_security_flags(nvdimm, NVDIMM_MASTER);
 458         if (nvdimm->sec.overwrite_state)
 459                 sysfs_notify_dirent(nvdimm->sec.overwrite_state);
 460         put_device(&nvdimm->dev);
 461 }
 462
 463 void nvdimm_security_overwrite_query(struct work_struct *work)
 464 {
 465         struct nvdimm *nvdimm =
 466                 container_of(work, typeof(*nvdimm), dwork.work);
 467
 468         nvdimm_bus_lock(&nvdimm->dev);
 469         __nvdimm_security_overwrite_query(nvdimm);
 470         nvdimm_bus_unlock(&nvdimm->dev);
 471 }
 472
 473 #define OPS                                                     \
 474         C( OP_FREEZE,           "freeze",               1),     \
 475         C( OP_DISABLE,          "disable",              2),     \
 476         C( OP_UPDATE,           "update",               3),     \
 477         C( OP_ERASE,            "erase",                2),     \
 478         C( OP_OVERWRITE,        "overwrite",            2),     \
 479         C( OP_MASTER_UPDATE,    "master_update",        3),     \
 480         C( OP_MASTER_ERASE,     "master_erase",         2)
 481 #undef C
 482 #define C(a, b, c) a
 483 enum nvdimmsec_op_ids { OPS };
 484 #undef C
 485 #define C(a, b, c) { b, c }
 486 static struct {
 487         const char *name;
 488         int args;
 489 } ops[] = { OPS };
 490 #undef C
 491
 492 #define SEC_CMD_SIZE 32
 493 #define KEY_ID_SIZE 10
 494
 495 ssize_t nvdimm_security_store(struct device *dev, const char *buf, size_t len)
 496 {
 497         struct nvdimm *nvdimm = to_nvdimm(dev);
 498         ssize_t rc;
 499         char cmd[SEC_CMD_SIZE+1], keystr[KEY_ID_SIZE+1],
 500                 nkeystr[KEY_ID_SIZE+1];
 501         unsigned int key, newkey;
 502         int i;
 503
 504         rc = sscanf(buf, "%"__stringify(SEC_CMD_SIZE)"s"
 505                         " %"__stringify(KEY_ID_SIZE)"s"
 506                         " %"__stringify(KEY_ID_SIZE)"s",
 507                         cmd, keystr, nkeystr);
 508         if (rc < 1)
 509                 return -EINVAL;
 510         for (i = 0; i < ARRAY_SIZE(ops); i++)
 511                 if (sysfs_streq(cmd, ops[i].name))
 512                         break;
 513         if (i >= ARRAY_SIZE(ops))
 514                 return -EINVAL;
 515         if (ops[i].args > 1)
 516                 rc = kstrtouint(keystr, 0, &key);
 517         if (rc >= 0 && ops[i].args > 2)
 518                 rc = kstrtouint(nkeystr, 0, &newkey);
 519         if (rc < 0)
 520                 return rc;
 521
 522         if (i == OP_FREEZE) {
 523                 dev_dbg(dev, "freeze\n");
 524                 rc = nvdimm_security_freeze(nvdimm);
 525         } else if (i == OP_DISABLE) {
 526                 dev_dbg(dev, "disable %u\n", key);
 527                 rc = security_disable(nvdimm, key);
 528         } else if (i == OP_UPDATE || i == OP_MASTER_UPDATE) {
 529                 dev_dbg(dev, "%s %u %u\n", ops[i].name, key, newkey);
 530                 rc = security_update(nvdimm, key, newkey, i == OP_UPDATE
 531                                 ? NVDIMM_USER : NVDIMM_MASTER);
 532         } else if (i == OP_ERASE || i == OP_MASTER_ERASE) {
 533                 dev_dbg(dev, "%s %u\n", ops[i].name, key);
 534                 if (atomic_read(&nvdimm->busy)) {
 535                         dev_dbg(dev, "Unable to secure erase while DIMM active.\n");
 536                         return -EBUSY;
 537                 }
 538                 rc = security_erase(nvdimm, key, i == OP_ERASE
 539                                 ? NVDIMM_USER : NVDIMM_MASTER);
 540         } else if (i == OP_OVERWRITE) {
 541                 dev_dbg(dev, "overwrite %u\n", key);
 542                 if (atomic_read(&nvdimm->busy)) {
 543                         dev_dbg(dev, "Unable to overwrite while DIMM active.\n");
 544                         return -EBUSY;
 545                 }
 546                 rc = security_overwrite(nvdimm, key);
 547         } else
 548                 return -EINVAL;
 549
 550         if (rc == 0)
 551                 rc = len;
 552         return rc;
 553 }