drivers/firmware/efivars.c

   1 /*
   2  * EFI Variables - efivars.c
   3  *
   4  * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
   5  * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
   6  *
   7  * This code takes all variables accessible from EFI runtime and
   8  *  exports them via sysfs
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or
  13  *  (at your option) any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful,
  16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *  GNU General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License
  21  *  along with this program; if not, write to the Free Software
  22  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  *
  24  * Changelog:
  25  *
  26  *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
  27  *   remove check for efi_enabled in exit
  28  *   add MODULE_VERSION
  29  *
  30  *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
  31  *   minor bug fixes
  32  *
  33  *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
  34  *   converted driver to export variable information via sysfs
  35  *   and moved to drivers/firmware directory
  36  *   bumped revision number to v0.07 to reflect conversion & move
  37  *
  38  *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
  39  *   fix locking per Peter Chubb's findings
  40  *
  41  *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
  42  *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
  43  *
  44  *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
  45  *   use list_for_each_safe when deleting vars.
  46  *   remove ifdef CONFIG_SMP around include <linux/smp.h>
  47  *   v0.04 release to linux-ia64@linuxia64.org
  48  *
  49  *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
  50  *   Moved vars from /proc/efi to /proc/efi/vars, and made
  51  *   efi.c own the /proc/efi directory.
  52  *   v0.03 release to linux-ia64@linuxia64.org
  53  *
  54  *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
  55  *   At the request of Stephane, moved ownership of /proc/efi
  56  *   to efi.c, and now efivars lives under /proc/efi/vars.
  57  *
  58  *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
  59  *   Feedback received from Stephane Eranian incorporated.
  60  *   efivar_write() checks copy_from_user() return value.
  61  *   efivar_read/write() returns proper errno.
  62  *   v0.02 release to linux-ia64@linuxia64.org
  63  *
  64  *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
  65  *   v0.01 release to linux-ia64@linuxia64.org
  66  */
  67
  68 #include <linux/capability.h>
  69 #include <linux/types.h>
  70 #include <linux/errno.h>
  71 #include <linux/init.h>
  72 #include <linux/mm.h>
  73 #include <linux/module.h>
  74 #include <linux/string.h>
  75 #include <linux/smp.h>
  76 #include <linux/efi.h>
  77 #include <linux/sysfs.h>
  78 #include <linux/kobject.h>
  79 #include <linux/device.h>
  80 #include <linux/slab.h>
  81 #include <linux/pstore.h>
  82
  83 #include <asm/uaccess.h>
  84
  85 #define EFIVARS_VERSION "0.08"
  86 #define EFIVARS_DATE "2004-May-17"
  87
  88 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
  89 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
  90 MODULE_LICENSE("GPL");
  91 MODULE_VERSION(EFIVARS_VERSION);
  92
  93 #define DUMP_NAME_LEN 52
  94
  95 /*
  96  * The maximum size of VariableName + Data = 1024
  97  * Therefore, it's reasonable to save that much
  98  * space in each part of the structure,
  99  * and we use a page for reading/writing.
 100  */
 101
 102 struct efi_variable {
 103         efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
 104         efi_guid_t    VendorGuid;
 105         unsigned long DataSize;
 106         __u8          Data[1024];
 107         efi_status_t  Status;
 108         __u32         Attributes;
 109 } __attribute__((packed));
 110
 111
 112 struct efivar_entry {
 113         struct efivars *efivars;
 114         struct efi_variable var;
 115         struct list_head list;
 116         struct kobject kobj;
 117 };
 118
 119 struct efivar_attribute {
 120         struct attribute attr;
 121         ssize_t (*show) (struct efivar_entry *entry, char *buf);
 122         ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
 123 };
 124
 125 #define PSTORE_EFI_ATTRIBUTES \
 126         (EFI_VARIABLE_NON_VOLATILE | \
 127          EFI_VARIABLE_BOOTSERVICE_ACCESS | \
 128          EFI_VARIABLE_RUNTIME_ACCESS)
 129
 130 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
 131 struct efivar_attribute efivar_attr_##_name = { \
 132         .attr = {.name = __stringify(_name), .mode = _mode}, \
 133         .show = _show, \
 134         .store = _store, \
 135 };
 136
 137 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
 138 #define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)
 139
 140 /*
 141  * Prototype for sysfs creation function
 142  */
 143 static int
 144 efivar_create_sysfs_entry(struct efivars *efivars,
 145                           unsigned long variable_name_size,
 146                           efi_char16_t *variable_name,
 147                           efi_guid_t *vendor_guid);
 148
 149 /* Return the number of unicode characters in data */
 150 static unsigned long
 151 utf16_strnlen(efi_char16_t *s, size_t maxlength)
 152 {
 153         unsigned long length = 0;
 154
 155         while (*s++ != 0 && length < maxlength)
 156                 length++;
 157         return length;
 158 }
 159
 160 static inline unsigned long
 161 utf16_strlen(efi_char16_t *s)
 162 {
 163         return utf16_strnlen(s, ~0UL);
 164 }
 165
 166 /*
 167  * Return the number of bytes is the length of this string
 168  * Note: this is NOT the same as the number of unicode characters
 169  */
 170 static inline unsigned long
 171 utf16_strsize(efi_char16_t *data, unsigned long maxlength)
 172 {
 173         return utf16_strnlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
 174 }
 175
 176 static inline int
 177 utf16_strncmp(const efi_char16_t *a, const efi_char16_t *b, size_t len)
 178 {
 179         while (1) {
 180                 if (len == 0)
 181                         return 0;
 182                 if (*a < *b)
 183                         return -1;
 184                 if (*a > *b)
 185                         return 1;
 186                 if (*a == 0) /* implies *b == 0 */
 187                         return 0;
 188                 a++;
 189                 b++;
 190                 len--;
 191         }
 192 }
 193
 194 static bool
 195 validate_device_path(struct efi_variable *var, int match, u8 *buffer,
 196                      unsigned long len)
 197 {
 198         struct efi_generic_dev_path *node;
 199         int offset = 0;
 200
 201         node = (struct efi_generic_dev_path *)buffer;
 202
 203         if (len < sizeof(*node))
 204                 return false;
 205
 206         while (offset <= len - sizeof(*node) &&
 207                node->length >= sizeof(*node) &&
 208                 node->length <= len - offset) {
 209                 offset += node->length;
 210
 211                 if ((node->type == EFI_DEV_END_PATH ||
 212                      node->type == EFI_DEV_END_PATH2) &&
 213                     node->sub_type == EFI_DEV_END_ENTIRE)
 214                         return true;
 215
 216                 node = (struct efi_generic_dev_path *)(buffer + offset);
 217         }
 218
 219         /*
 220          * If we're here then either node->length pointed past the end
 221          * of the buffer or we reached the end of the buffer without
 222          * finding a device path end node.
 223          */
 224         return false;
 225 }
 226
 227 static bool
 228 validate_boot_order(struct efi_variable *var, int match, u8 *buffer,
 229                     unsigned long len)
 230 {
 231         /* An array of 16-bit integers */
 232         if ((len % 2) != 0)
 233                 return false;
 234
 235         return true;
 236 }
 237
 238 static bool
 239 validate_load_option(struct efi_variable *var, int match, u8 *buffer,
 240                      unsigned long len)
 241 {
 242         u16 filepathlength;
 243         int i, desclength = 0, namelen;
 244
 245         namelen = utf16_strnlen(var->VariableName, sizeof(var->VariableName));
 246
 247         /* Either "Boot" or "Driver" followed by four digits of hex */
 248         for (i = match; i < match+4; i++) {
 249                 if (var->VariableName[i] > 127 ||
 250                     hex_to_bin(var->VariableName[i] & 0xff) < 0)
 251                         return true;
 252         }
 253
 254         /* Reject it if there's 4 digits of hex and then further content */
 255         if (namelen > match + 4)
 256                 return false;
 257
 258         /* A valid entry must be at least 8 bytes */
 259         if (len < 8)
 260                 return false;
 261
 262         filepathlength = buffer[4] | buffer[5] << 8;
 263
 264         /*
 265          * There's no stored length for the description, so it has to be
 266          * found by hand
 267          */
 268         desclength = utf16_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
 269
 270         /* Each boot entry must have a descriptor */
 271         if (!desclength)
 272                 return false;
 273
 274         /*
 275          * If the sum of the length of the description, the claimed filepath
 276          * length and the original header are greater than the length of the
 277          * variable, it's malformed
 278          */
 279         if ((desclength + filepathlength + 6) > len)
 280                 return false;
 281
 282         /*
 283          * And, finally, check the filepath
 284          */
 285         return validate_device_path(var, match, buffer + desclength + 6,
 286                                     filepathlength);
 287 }
 288
 289 static bool
 290 validate_uint16(struct efi_variable *var, int match, u8 *buffer,
 291                 unsigned long len)
 292 {
 293         /* A single 16-bit integer */
 294         if (len != 2)
 295                 return false;
 296
 297         return true;
 298 }
 299
 300 static bool
 301 validate_ascii_string(struct efi_variable *var, int match, u8 *buffer,
 302                       unsigned long len)
 303 {
 304         int i;
 305
 306         for (i = 0; i < len; i++) {
 307                 if (buffer[i] > 127)
 308                         return false;
 309
 310                 if (buffer[i] == 0)
 311                         return true;
 312         }
 313
 314         return false;
 315 }
 316
 317 struct variable_validate {
 318         char *name;
 319         bool (*validate)(struct efi_variable *var, int match, u8 *data,
 320                          unsigned long len);
 321 };
 322
 323 static const struct variable_validate variable_validate[] = {
 324         { "BootNext", validate_uint16 },
 325         { "BootOrder", validate_boot_order },
 326         { "DriverOrder", validate_boot_order },
 327         { "Boot*", validate_load_option },
 328         { "Driver*", validate_load_option },
 329         { "ConIn", validate_device_path },
 330         { "ConInDev", validate_device_path },
 331         { "ConOut", validate_device_path },
 332         { "ConOutDev", validate_device_path },
 333         { "ErrOut", validate_device_path },
 334         { "ErrOutDev", validate_device_path },
 335         { "Timeout", validate_uint16 },
 336         { "Lang", validate_ascii_string },
 337         { "PlatformLang", validate_ascii_string },
 338         { "", NULL },
 339 };
 340
 341 static bool
 342 validate_var(struct efi_variable *var, u8 *data, unsigned long len)
 343 {
 344         int i;
 345         u16 *unicode_name = var->VariableName;
 346
 347         for (i = 0; variable_validate[i].validate != NULL; i++) {
 348                 const char *name = variable_validate[i].name;
 349                 int match;
 350
 351                 for (match = 0; ; match++) {
 352                         char c = name[match];
 353                         u16 u = unicode_name[match];
 354
 355                         /* All special variables are plain ascii */
 356                         if (u > 127)
 357                                 return true;
 358
 359                         /* Wildcard in the matching name means we've matched */
 360                         if (c == '*')
 361                                 return variable_validate[i].validate(var,
 362                                                              match, data, len);
 363
 364                         /* Case sensitive match */
 365                         if (c != u)
 366                                 break;
 367
 368                         /* Reached the end of the string while matching */
 369                         if (!c)
 370                                 return variable_validate[i].validate(var,
 371                                                              match, data, len);
 372                 }
 373         }
 374
 375         return true;
 376 }
 377
 378 static efi_status_t
 379 get_var_data_locked(struct efivars *efivars, struct efi_variable *var)
 380 {
 381         efi_status_t status;
 382
 383         var->DataSize = 1024;
 384         status = efivars->ops->get_variable(var->VariableName,
 385                                             &var->VendorGuid,
 386                                             &var->Attributes,
 387                                             &var->DataSize,
 388                                             var->Data);
 389         return status;
 390 }
 391
 392 static efi_status_t
 393 get_var_data(struct efivars *efivars, struct efi_variable *var)
 394 {
 395         efi_status_t status;
 396
 397         spin_lock(&efivars->lock);
 398         status = get_var_data_locked(efivars, var);
 399         spin_unlock(&efivars->lock);
 400
 401         if (status != EFI_SUCCESS) {
 402                 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
 403                         status);
 404         }
 405         return status;
 406 }
 407
 408 static ssize_t
 409 efivar_guid_read(struct efivar_entry *entry, char *buf)
 410 {
 411         struct efi_variable *var = &entry->var;
 412         char *str = buf;
 413
 414         if (!entry || !buf)
 415                 return 0;
 416
 417         efi_guid_unparse(&var->VendorGuid, str);
 418         str += strlen(str);
 419         str += sprintf(str, "\n");
 420
 421         return str - buf;
 422 }
 423
 424 static ssize_t
 425 efivar_attr_read(struct efivar_entry *entry, char *buf)
 426 {
 427         struct efi_variable *var = &entry->var;
 428         char *str = buf;
 429         efi_status_t status;
 430
 431         if (!entry || !buf)
 432                 return -EINVAL;
 433
 434         status = get_var_data(entry->efivars, var);
 435         if (status != EFI_SUCCESS)
 436                 return -EIO;
 437
 438         if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
 439                 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
 440         if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
 441                 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
 442         if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
 443                 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
 444         if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
 445                 str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
 446         if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
 447                 str += sprintf(str,
 448                         "EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
 449         if (var->Attributes &
 450                         EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
 451                 str += sprintf(str,
 452                         "EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
 453         if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
 454                 str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
 455         return str - buf;
 456 }
 457
 458 static ssize_t
 459 efivar_size_read(struct efivar_entry *entry, char *buf)
 460 {
 461         struct efi_variable *var = &entry->var;
 462         char *str = buf;
 463         efi_status_t status;
 464
 465         if (!entry || !buf)
 466                 return -EINVAL;
 467
 468         status = get_var_data(entry->efivars, var);
 469         if (status != EFI_SUCCESS)
 470                 return -EIO;
 471
 472         str += sprintf(str, "0x%lx\n", var->DataSize);
 473         return str - buf;
 474 }
 475
 476 static ssize_t
 477 efivar_data_read(struct efivar_entry *entry, char *buf)
 478 {
 479         struct efi_variable *var = &entry->var;
 480         efi_status_t status;
 481
 482         if (!entry || !buf)
 483                 return -EINVAL;
 484
 485         status = get_var_data(entry->efivars, var);
 486         if (status != EFI_SUCCESS)
 487                 return -EIO;
 488
 489         memcpy(buf, var->Data, var->DataSize);
 490         return var->DataSize;
 491 }
 492 /*
 493  * We allow each variable to be edited via rewriting the
 494  * entire efi variable structure.
 495  */
 496 static ssize_t
 497 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 498 {
 499         struct efi_variable *new_var, *var = &entry->var;
 500         struct efivars *efivars = entry->efivars;
 501         efi_status_t status = EFI_NOT_FOUND;
 502
 503         if (count != sizeof(struct efi_variable))
 504                 return -EINVAL;
 505
 506         new_var = (struct efi_variable *)buf;
 507         /*
 508          * If only updating the variable data, then the name
 509          * and guid should remain the same
 510          */
 511         if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
 512                 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
 513                 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
 514                 return -EINVAL;
 515         }
 516
 517         if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
 518                 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
 519                 return -EINVAL;
 520         }
 521
 522         if ((new_var->Attributes & ~EFI_VARIABLE_MASK) != 0 ||
 523             validate_var(new_var, new_var->Data, new_var->DataSize) == false) {
 524                 printk(KERN_ERR "efivars: Malformed variable content\n");
 525                 return -EINVAL;
 526         }
 527
 528         spin_lock(&efivars->lock);
 529         status = efivars->ops->set_variable(new_var->VariableName,
 530                                             &new_var->VendorGuid,
 531                                             new_var->Attributes,
 532                                             new_var->DataSize,
 533                                             new_var->Data);
 534
 535         spin_unlock(&efivars->lock);
 536
 537         if (status != EFI_SUCCESS) {
 538                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 539                         status);
 540                 return -EIO;
 541         }
 542
 543         memcpy(&entry->var, new_var, count);
 544         return count;
 545 }
 546
 547 static ssize_t
 548 efivar_show_raw(struct efivar_entry *entry, char *buf)
 549 {
 550         struct efi_variable *var = &entry->var;
 551         efi_status_t status;
 552
 553         if (!entry || !buf)
 554                 return 0;
 555
 556         status = get_var_data(entry->efivars, var);
 557         if (status != EFI_SUCCESS)
 558                 return -EIO;
 559
 560         memcpy(buf, var, sizeof(*var));
 561         return sizeof(*var);
 562 }
 563
 564 /*
 565  * Generic read/write functions that call the specific functions of
 566  * the attributes...
 567  */
 568 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
 569                                 char *buf)
 570 {
 571         struct efivar_entry *var = to_efivar_entry(kobj);
 572         struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 573         ssize_t ret = -EIO;
 574
 575         if (!capable(CAP_SYS_ADMIN))
 576                 return -EACCES;
 577
 578         if (efivar_attr->show) {
 579                 ret = efivar_attr->show(var, buf);
 580         }
 581         return ret;
 582 }
 583
 584 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
 585                                 const char *buf, size_t count)
 586 {
 587         struct efivar_entry *var = to_efivar_entry(kobj);
 588         struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 589         ssize_t ret = -EIO;
 590
 591         if (!capable(CAP_SYS_ADMIN))
 592                 return -EACCES;
 593
 594         if (efivar_attr->store)
 595                 ret = efivar_attr->store(var, buf, count);
 596
 597         return ret;
 598 }
 599
 600 static const struct sysfs_ops efivar_attr_ops = {
 601         .show = efivar_attr_show,
 602         .store = efivar_attr_store,
 603 };
 604
 605 static void efivar_release(struct kobject *kobj)
 606 {
 607         struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
 608         kfree(var);
 609 }
 610
 611 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
 612 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
 613 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
 614 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
 615 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
 616
 617 static struct attribute *def_attrs[] = {
 618         &efivar_attr_guid.attr,
 619         &efivar_attr_size.attr,
 620         &efivar_attr_attributes.attr,
 621         &efivar_attr_data.attr,
 622         &efivar_attr_raw_var.attr,
 623         NULL,
 624 };
 625
 626 static struct kobj_type efivar_ktype = {
 627         .release = efivar_release,
 628         .sysfs_ops = &efivar_attr_ops,
 629         .default_attrs = def_attrs,
 630 };
 631
 632 static struct pstore_info efi_pstore_info;
 633
 634 static inline void
 635 efivar_unregister(struct efivar_entry *var)
 636 {
 637         kobject_put(&var->kobj);
 638 }
 639
 640 #ifdef CONFIG_PSTORE
 641
 642 static int efi_pstore_open(struct pstore_info *psi)
 643 {
 644         struct efivars *efivars = psi->data;
 645
 646         spin_lock(&efivars->lock);
 647         efivars->walk_entry = list_first_entry(&efivars->list,
 648                                                struct efivar_entry, list);
 649         return 0;
 650 }
 651
 652 static int efi_pstore_close(struct pstore_info *psi)
 653 {
 654         struct efivars *efivars = psi->data;
 655
 656         spin_unlock(&efivars->lock);
 657         return 0;
 658 }
 659
 660 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 661                                struct timespec *timespec,
 662                                char **buf, struct pstore_info *psi)
 663 {
 664         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 665         struct efivars *efivars = psi->data;
 666         char name[DUMP_NAME_LEN];
 667         int i;
 668         unsigned int part, size;
 669         unsigned long time;
 670
 671         while (&efivars->walk_entry->list != &efivars->list) {
 672                 if (!efi_guidcmp(efivars->walk_entry->var.VendorGuid,
 673                                  vendor)) {
 674                         for (i = 0; i < DUMP_NAME_LEN; i++) {
 675                                 name[i] = efivars->walk_entry->var.VariableName[i];
 676                         }
 677                         if (sscanf(name, "dump-type%u-%u-%lu", type, &part, &time) == 3) {
 678                                 *id = part;
 679                                 timespec->tv_sec = time;
 680                                 timespec->tv_nsec = 0;
 681                                 get_var_data_locked(efivars, &efivars->walk_entry->var);
 682                                 size = efivars->walk_entry->var.DataSize;
 683                                 *buf = kmalloc(size, GFP_KERNEL);
 684                                 if (*buf == NULL)
 685                                         return -ENOMEM;
 686                                 memcpy(*buf, efivars->walk_entry->var.Data,
 687                                        size);
 688                                 efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
 689                                                    struct efivar_entry, list);
 690                                 return size;
 691                         }
 692                 }
 693                 efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
 694                                                  struct efivar_entry, list);
 695         }
 696         return 0;
 697 }
 698
 699 static int efi_pstore_write(enum pstore_type_id type,
 700                 enum kmsg_dump_reason reason, u64 *id,
 701                 unsigned int part, size_t size, struct pstore_info *psi)
 702 {
 703         char name[DUMP_NAME_LEN];
 704         char stub_name[DUMP_NAME_LEN];
 705         efi_char16_t efi_name[DUMP_NAME_LEN];
 706         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 707         struct efivars *efivars = psi->data;
 708         struct efivar_entry *entry, *found = NULL;
 709         int i, ret = 0;
 710
 711         sprintf(stub_name, "dump-type%u-%u-", type, part);
 712         sprintf(name, "%s%lu", stub_name, get_seconds());
 713
 714         spin_lock(&efivars->lock);
 715
 716         for (i = 0; i < DUMP_NAME_LEN; i++)
 717                 efi_name[i] = stub_name[i];
 718
 719         /*
 720          * Clean up any entries with the same name
 721          */
 722
 723         list_for_each_entry(entry, &efivars->list, list) {
 724                 get_var_data_locked(efivars, &entry->var);
 725
 726                 if (efi_guidcmp(entry->var.VendorGuid, vendor))
 727                         continue;
 728                 if (utf16_strncmp(entry->var.VariableName, efi_name,
 729                                   utf16_strlen(efi_name)))
 730                         continue;
 731                 /* Needs to be a prefix */
 732                 if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
 733                         continue;
 734
 735                 /* found */
 736                 found = entry;
 737                 efivars->ops->set_variable(entry->var.VariableName,
 738                                            &entry->var.VendorGuid,
 739                                            PSTORE_EFI_ATTRIBUTES,
 740                                            0, NULL);
 741         }
 742
 743         if (found)
 744                 list_del(&found->list);
 745
 746         for (i = 0; i < DUMP_NAME_LEN; i++)
 747                 efi_name[i] = name[i];
 748
 749         efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,
 750                                    size, psi->buf);
 751
 752         spin_unlock(&efivars->lock);
 753
 754         if (found)
 755                 efivar_unregister(found);
 756
 757         if (size)
 758                 ret = efivar_create_sysfs_entry(efivars,
 759                                           utf16_strsize(efi_name,
 760                                                         DUMP_NAME_LEN * 2),
 761                                           efi_name, &vendor);
 762
 763         *id = part;
 764         return ret;
 765 };
 766
 767 static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 768                             struct pstore_info *psi)
 769 {
 770         efi_pstore_write(type, 0, &id, (unsigned int)id, 0, psi);
 771
 772         return 0;
 773 }
 774 #else
 775 static int efi_pstore_open(struct pstore_info *psi)
 776 {
 777         return 0;
 778 }
 779
 780 static int efi_pstore_close(struct pstore_info *psi)
 781 {
 782         return 0;
 783 }
 784
 785 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 786                                struct timespec *timespec,
 787                                char **buf, struct pstore_info *psi)
 788 {
 789         return -1;
 790 }
 791
 792 static int efi_pstore_write(enum pstore_type_id type,
 793                 enum kmsg_dump_reason reason, u64 *id,
 794                 unsigned int part, size_t size, struct pstore_info *psi)
 795 {
 796         return 0;
 797 }
 798
 799 static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 800                             struct pstore_info *psi)
 801 {
 802         return 0;
 803 }
 804 #endif
 805
 806 static struct pstore_info efi_pstore_info = {
 807         .owner          = THIS_MODULE,
 808         .name           = "efi",
 809         .open           = efi_pstore_open,
 810         .close          = efi_pstore_close,
 811         .read           = efi_pstore_read,
 812         .write          = efi_pstore_write,
 813         .erase          = efi_pstore_erase,
 814 };
 815
 816 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 817                              struct bin_attribute *bin_attr,
 818                              char *buf, loff_t pos, size_t count)
 819 {
 820         struct efi_variable *new_var = (struct efi_variable *)buf;
 821         struct efivars *efivars = bin_attr->private;
 822         struct efivar_entry *search_efivar, *n;
 823         unsigned long strsize1, strsize2;
 824         efi_status_t status = EFI_NOT_FOUND;
 825         int found = 0;
 826
 827         if (!capable(CAP_SYS_ADMIN))
 828                 return -EACCES;
 829
 830         if ((new_var->Attributes & ~EFI_VARIABLE_MASK) != 0 ||
 831             validate_var(new_var, new_var->Data, new_var->DataSize) == false) {
 832                 printk(KERN_ERR "efivars: Malformed variable content\n");
 833                 return -EINVAL;
 834         }
 835
 836         spin_lock(&efivars->lock);
 837
 838         /*
 839          * Does this variable already exist?
 840          */
 841         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
 842                 strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
 843                 strsize2 = utf16_strsize(new_var->VariableName, 1024);
 844                 if (strsize1 == strsize2 &&
 845                         !memcmp(&(search_efivar->var.VariableName),
 846                                 new_var->VariableName, strsize1) &&
 847                         !efi_guidcmp(search_efivar->var.VendorGuid,
 848                                 new_var->VendorGuid)) {
 849                         found = 1;
 850                         break;
 851                 }
 852         }
 853         if (found) {
 854                 spin_unlock(&efivars->lock);
 855                 return -EINVAL;
 856         }
 857
 858         /* now *really* create the variable via EFI */
 859         status = efivars->ops->set_variable(new_var->VariableName,
 860                                             &new_var->VendorGuid,
 861                                             new_var->Attributes,
 862                                             new_var->DataSize,
 863                                             new_var->Data);
 864
 865         if (status != EFI_SUCCESS) {
 866                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 867                         status);
 868                 spin_unlock(&efivars->lock);
 869                 return -EIO;
 870         }
 871         spin_unlock(&efivars->lock);
 872
 873         /* Create the entry in sysfs.  Locking is not required here */
 874         status = efivar_create_sysfs_entry(efivars,
 875                                            utf16_strsize(new_var->VariableName,
 876                                                          1024),
 877                                            new_var->VariableName,
 878                                            &new_var->VendorGuid);
 879         if (status) {
 880                 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
 881         }
 882         return count;
 883 }
 884
 885 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
 886                              struct bin_attribute *bin_attr,
 887                              char *buf, loff_t pos, size_t count)
 888 {
 889         struct efi_variable *del_var = (struct efi_variable *)buf;
 890         struct efivars *efivars = bin_attr->private;
 891         struct efivar_entry *search_efivar, *n;
 892         unsigned long strsize1, strsize2;
 893         efi_status_t status = EFI_NOT_FOUND;
 894         int found = 0;
 895
 896         if (!capable(CAP_SYS_ADMIN))
 897                 return -EACCES;
 898
 899         spin_lock(&efivars->lock);
 900
 901         /*
 902          * Does this variable already exist?
 903          */
 904         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
 905                 strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
 906                 strsize2 = utf16_strsize(del_var->VariableName, 1024);
 907                 if (strsize1 == strsize2 &&
 908                         !memcmp(&(search_efivar->var.VariableName),
 909                                 del_var->VariableName, strsize1) &&
 910                         !efi_guidcmp(search_efivar->var.VendorGuid,
 911                                 del_var->VendorGuid)) {
 912                         found = 1;
 913                         break;
 914                 }
 915         }
 916         if (!found) {
 917                 spin_unlock(&efivars->lock);
 918                 return -EINVAL;
 919         }
 920         /* force the Attributes/DataSize to 0 to ensure deletion */
 921         del_var->Attributes = 0;
 922         del_var->DataSize = 0;
 923
 924         status = efivars->ops->set_variable(del_var->VariableName,
 925                                             &del_var->VendorGuid,
 926                                             del_var->Attributes,
 927                                             del_var->DataSize,
 928                                             del_var->Data);
 929
 930         if (status != EFI_SUCCESS) {
 931                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 932                         status);
 933                 spin_unlock(&efivars->lock);
 934                 return -EIO;
 935         }
 936         list_del(&search_efivar->list);
 937         /* We need to release this lock before unregistering. */
 938         spin_unlock(&efivars->lock);
 939         efivar_unregister(search_efivar);
 940
 941         /* It's dead Jim.... */
 942         return count;
 943 }
 944
 945 /*
 946  * Returns the size of variable_name, in bytes, including the
 947  * terminating NULL character, or variable_name_size if no NULL
 948  * character is found among the first variable_name_size bytes.
 949  */
 950 static unsigned long var_name_strnsize(efi_char16_t *variable_name,
 951                                        unsigned long variable_name_size)
 952 {
 953         unsigned long len;
 954         efi_char16_t c;
 955
 956         /*
 957          * The variable name is, by definition, a NULL-terminated
 958          * string, so make absolutely sure that variable_name_size is
 959          * the value we expect it to be. If not, return the real size.
 960          */
 961         for (len = 2; len <= variable_name_size; len += sizeof(c)) {
 962                 c = variable_name[(len / sizeof(c)) - 1];
 963                 if (!c)
 964                         break;
 965         }
 966
 967         return min(len, variable_name_size);
 968 }
 969
 970 /*
 971  * Let's not leave out systab information that snuck into
 972  * the efivars driver
 973  */
 974 static ssize_t systab_show(struct kobject *kobj,
 975                            struct kobj_attribute *attr, char *buf)
 976 {
 977         char *str = buf;
 978
 979         if (!kobj || !buf)
 980                 return -EINVAL;
 981
 982         if (efi.mps != EFI_INVALID_TABLE_ADDR)
 983                 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
 984         if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
 985                 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
 986         if (efi.acpi != EFI_INVALID_TABLE_ADDR)
 987                 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
 988         if (efi.smbios != EFI_INVALID_TABLE_ADDR)
 989                 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
 990         if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
 991                 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
 992         if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
 993                 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
 994         if (efi.uga != EFI_INVALID_TABLE_ADDR)
 995                 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
 996
 997         return str - buf;
 998 }
 999
1000 static struct kobj_attribute efi_attr_systab =
1001                         __ATTR(systab, 0400, systab_show, NULL);
1002
1003 static struct attribute *efi_subsys_attrs[] = {
1004         &efi_attr_systab.attr,
1005         NULL,   /* maybe more in the future? */
1006 };
1007
1008 static struct attribute_group efi_subsys_attr_group = {
1009         .attrs = efi_subsys_attrs,
1010 };
1011
1012 static struct kobject *efi_kobj;
1013
1014 /*
1015  * efivar_create_sysfs_entry()
1016  * Requires:
1017  *    variable_name_size = number of bytes required to hold
1018  *                         variable_name (not counting the NULL
1019  *                         character at the end.
1020  *    efivars->lock is not held on entry or exit.
1021  * Returns 1 on failure, 0 on success
1022  */
1023 static int
1024 efivar_create_sysfs_entry(struct efivars *efivars,
1025                           unsigned long variable_name_size,
1026                           efi_char16_t *variable_name,
1027                           efi_guid_t *vendor_guid)
1028 {
1029         int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
1030         char *short_name;
1031         struct efivar_entry *new_efivar;
1032
1033         short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
1034         new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
1035
1036         if (!short_name || !new_efivar)  {
1037                 kfree(short_name);
1038                 kfree(new_efivar);
1039                 return 1;
1040         }
1041
1042         new_efivar->efivars = efivars;
1043         memcpy(new_efivar->var.VariableName, variable_name,
1044                 variable_name_size);
1045         memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
1046
1047         /* Convert Unicode to normal chars (assume top bits are 0),
1048            ala UTF-8 */
1049         for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
1050                 short_name[i] = variable_name[i] & 0xFF;
1051         }
1052         /* This is ugly, but necessary to separate one vendor's
1053            private variables from another's.         */
1054
1055         *(short_name + strlen(short_name)) = '-';
1056         efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
1057
1058         new_efivar->kobj.kset = efivars->kset;
1059         i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
1060                                  "%s", short_name);
1061         if (i) {
1062                 kfree(short_name);
1063                 kfree(new_efivar);
1064                 return 1;
1065         }
1066
1067         kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
1068         kfree(short_name);
1069         short_name = NULL;
1070
1071         spin_lock(&efivars->lock);
1072         list_add(&new_efivar->list, &efivars->list);
1073         spin_unlock(&efivars->lock);
1074
1075         return 0;
1076 }
1077
1078 static int
1079 create_efivars_bin_attributes(struct efivars *efivars)
1080 {
1081         struct bin_attribute *attr;
1082         int error;
1083
1084         /* new_var */
1085         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
1086         if (!attr)
1087                 return -ENOMEM;
1088
1089         attr->attr.name = "new_var";
1090         attr->attr.mode = 0200;
1091         attr->write = efivar_create;
1092         attr->private = efivars;
1093         efivars->new_var = attr;
1094
1095         /* del_var */
1096         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
1097         if (!attr) {
1098                 error = -ENOMEM;
1099                 goto out_free;
1100         }
1101         attr->attr.name = "del_var";
1102         attr->attr.mode = 0200;
1103         attr->write = efivar_delete;
1104         attr->private = efivars;
1105         efivars->del_var = attr;
1106
1107         sysfs_bin_attr_init(efivars->new_var);
1108         sysfs_bin_attr_init(efivars->del_var);
1109
1110         /* Register */
1111         error = sysfs_create_bin_file(&efivars->kset->kobj,
1112                                       efivars->new_var);
1113         if (error) {
1114                 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
1115                         " due to error %d\n", error);
1116                 goto out_free;
1117         }
1118         error = sysfs_create_bin_file(&efivars->kset->kobj,
1119                                       efivars->del_var);
1120         if (error) {
1121                 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
1122                         " due to error %d\n", error);
1123                 sysfs_remove_bin_file(&efivars->kset->kobj,
1124                                       efivars->new_var);
1125                 goto out_free;
1126         }
1127
1128         return 0;
1129 out_free:
1130         kfree(efivars->del_var);
1131         efivars->del_var = NULL;
1132         kfree(efivars->new_var);
1133         efivars->new_var = NULL;
1134         return error;
1135 }
1136
1137 void unregister_efivars(struct efivars *efivars)
1138 {
1139         struct efivar_entry *entry, *n;
1140
1141         list_for_each_entry_safe(entry, n, &efivars->list, list) {
1142                 spin_lock(&efivars->lock);
1143                 list_del(&entry->list);
1144                 spin_unlock(&efivars->lock);
1145                 efivar_unregister(entry);
1146         }
1147         if (efivars->new_var)
1148                 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
1149         if (efivars->del_var)
1150                 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
1151         kfree(efivars->new_var);
1152         kfree(efivars->del_var);
1153         kset_unregister(efivars->kset);
1154 }
1155 EXPORT_SYMBOL_GPL(unregister_efivars);
1156
1157 int register_efivars(struct efivars *efivars,
1158                      const struct efivar_operations *ops,
1159                      struct kobject *parent_kobj)
1160 {
1161         efi_status_t status = EFI_NOT_FOUND;
1162         efi_guid_t vendor_guid;
1163         efi_char16_t *variable_name;
1164         unsigned long variable_name_size = 1024;
1165         int error = 0;
1166
1167         variable_name = kzalloc(variable_name_size, GFP_KERNEL);
1168         if (!variable_name) {
1169                 printk(KERN_ERR "efivars: Memory allocation failed.\n");
1170                 return -ENOMEM;
1171         }
1172
1173         spin_lock_init(&efivars->lock);
1174         INIT_LIST_HEAD(&efivars->list);
1175         efivars->ops = ops;
1176
1177         efivars->kset = kset_create_and_add("vars", NULL, parent_kobj);
1178         if (!efivars->kset) {
1179                 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
1180                 error = -ENOMEM;
1181                 goto out;
1182         }
1183
1184         /*
1185          * Per EFI spec, the maximum storage allocated for both
1186          * the variable name and variable data is 1024 bytes.
1187          */
1188
1189         do {
1190                 variable_name_size = 1024;
1191
1192                 status = ops->get_next_variable(&variable_name_size,
1193                                                 variable_name,
1194                                                 &vendor_guid);
1195                 switch (status) {
1196                 case EFI_SUCCESS:
1197                         variable_name_size = var_name_strnsize(variable_name,
1198                                                                variable_name_size);
1199                         efivar_create_sysfs_entry(efivars,
1200                                                   variable_name_size,
1201                                                   variable_name,
1202                                                   &vendor_guid);
1203                         break;
1204                 case EFI_NOT_FOUND:
1205                         break;
1206                 default:
1207                         printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
1208                                 status);
1209                         status = EFI_NOT_FOUND;
1210                         break;
1211                 }
1212         } while (status != EFI_NOT_FOUND);
1213
1214         error = create_efivars_bin_attributes(efivars);
1215         if (error)
1216                 unregister_efivars(efivars);
1217
1218         efivars->efi_pstore_info = efi_pstore_info;
1219
1220         efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
1221         if (efivars->efi_pstore_info.buf) {
1222                 efivars->efi_pstore_info.bufsize = 1024;
1223                 efivars->efi_pstore_info.data = efivars;
1224                 spin_lock_init(&efivars->efi_pstore_info.buf_lock);
1225                 pstore_register(&efivars->efi_pstore_info);
1226         }
1227
1228 out:
1229         kfree(variable_name);
1230
1231         return error;
1232 }
1233 EXPORT_SYMBOL_GPL(register_efivars);
1234
1235 static struct efivars __efivars;
1236 static struct efivar_operations ops;
1237
1238 /*
1239  * For now we register the efi subsystem with the firmware subsystem
1240  * and the vars subsystem with the efi subsystem.  In the future, it
1241  * might make sense to split off the efi subsystem into its own
1242  * driver, but for now only efivars will register with it, so just
1243  * include it here.
1244  */
1245
1246 static int __init
1247 efivars_init(void)
1248 {
1249         int error = 0;
1250
1251         printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
1252                EFIVARS_DATE);
1253
1254         if (!efi_enabled(EFI_RUNTIME_SERVICES))
1255                 return 0;
1256
1257         /* For now we'll register the efi directory at /sys/firmware/efi */
1258         efi_kobj = kobject_create_and_add("efi", firmware_kobj);
1259         if (!efi_kobj) {
1260                 printk(KERN_ERR "efivars: Firmware registration failed.\n");
1261                 return -ENOMEM;
1262         }
1263
1264         ops.get_variable = efi.get_variable;
1265         ops.set_variable = efi.set_variable;
1266         ops.get_next_variable = efi.get_next_variable;
1267         error = register_efivars(&__efivars, &ops, efi_kobj);
1268         if (error)
1269                 goto err_put;
1270
1271         /* Don't forget the systab entry */
1272         error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
1273         if (error) {
1274                 printk(KERN_ERR
1275                        "efivars: Sysfs attribute export failed with error %d.\n",
1276                        error);
1277                 goto err_unregister;
1278         }
1279
1280         return 0;
1281
1282 err_unregister:
1283         unregister_efivars(&__efivars);
1284 err_put:
1285         kobject_put(efi_kobj);
1286         return error;
1287 }
1288
1289 static void __exit
1290 efivars_exit(void)
1291 {
1292         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
1293                 unregister_efivars(&__efivars);
1294                 kobject_put(efi_kobj);
1295         }
1296 }
1297
1298 module_init(efivars_init);
1299 module_exit(efivars_exit);
1300