drivers/firmware/efi/esrt.c

   1 /*
   2  * esrt.c
   3  *
   4  * This module exports EFI System Resource Table (ESRT) entries into userspace
   5  * through the sysfs file system. The ESRT provides a read-only catalog of
   6  * system components for which the system accepts firmware upgrades via UEFI's
   7  * "Capsule Update" feature. This module allows userland utilities to evaluate
   8  * what firmware updates can be applied to this system, and potentially arrange
   9  * for those updates to occur.
  10  *
  11  * Data is currently found below /sys/firmware/efi/esrt/...
  12  */
  13 #define pr_fmt(fmt) "esrt: " fmt
  14
  15 #include <linux/capability.h>
  16 #include <linux/device.h>
  17 #include <linux/efi.h>
  18 #include <linux/init.h>
  19 #include <linux/io.h>
  20 #include <linux/kernel.h>
  21 #include <linux/kobject.h>
  22 #include <linux/list.h>
  23 #include <linux/memblock.h>
  24 #include <linux/slab.h>
  25 #include <linux/types.h>
  26
  27 #include <asm/io.h>
  28 #include <asm/early_ioremap.h>
  29
  30 struct efi_system_resource_entry_v1 {
  31         efi_guid_t      fw_class;
  32         u32             fw_type;
  33         u32             fw_version;
  34         u32             lowest_supported_fw_version;
  35         u32             capsule_flags;
  36         u32             last_attempt_version;
  37         u32             last_attempt_status;
  38 };
  39
  40 /*
  41  * _count and _version are what they seem like.  _max is actually just
  42  * accounting info for the firmware when creating the table; it should never
  43  * have been exposed to us.  To wit, the spec says:
  44  * The maximum number of resource array entries that can be within the
  45  * table without reallocating the table, must not be zero.
  46  * Since there's no guidance about what that means in terms of memory layout,
  47  * it means nothing to us.
  48  */
  49 struct efi_system_resource_table {
  50         u32     fw_resource_count;
  51         u32     fw_resource_count_max;
  52         u64     fw_resource_version;
  53         u8      entries[];
  54 };
  55
  56 static phys_addr_t esrt_data;
  57 static size_t esrt_data_size;
  58
  59 static struct efi_system_resource_table *esrt;
  60
  61 struct esre_entry {
  62         union {
  63                 struct efi_system_resource_entry_v1 *esre1;
  64         } esre;
  65
  66         struct kobject kobj;
  67         struct list_head list;
  68 };
  69
  70 /* global list of esre_entry. */
  71 static LIST_HEAD(entry_list);
  72
  73 /* entry attribute */
  74 struct esre_attribute {
  75         struct attribute attr;
  76         ssize_t (*show)(struct esre_entry *entry, char *buf);
  77         ssize_t (*store)(struct esre_entry *entry,
  78                          const char *buf, size_t count);
  79 };
  80
  81 static struct esre_entry *to_entry(struct kobject *kobj)
  82 {
  83         return container_of(kobj, struct esre_entry, kobj);
  84 }
  85
  86 static struct esre_attribute *to_attr(struct attribute *attr)
  87 {
  88         return container_of(attr, struct esre_attribute, attr);
  89 }
  90
  91 static ssize_t esre_attr_show(struct kobject *kobj,
  92                               struct attribute *_attr, char *buf)
  93 {
  94         struct esre_entry *entry = to_entry(kobj);
  95         struct esre_attribute *attr = to_attr(_attr);
  96
  97         /* Don't tell normal users what firmware versions we've got... */
  98         if (!capable(CAP_SYS_ADMIN))
  99                 return -EACCES;
 100
 101         return attr->show(entry, buf);
 102 }
 103
 104 static const struct sysfs_ops esre_attr_ops = {
 105         .show = esre_attr_show,
 106 };
 107
 108 /* Generic ESRT Entry ("ESRE") support. */
 109 static ssize_t fw_class_show(struct esre_entry *entry, char *buf)
 110 {
 111         char *str = buf;
 112
 113         efi_guid_to_str(&entry->esre.esre1->fw_class, str);
 114         str += strlen(str);
 115         str += sprintf(str, "\n");
 116
 117         return str - buf;
 118 }
 119
 120 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400);
 121
 122 #define esre_attr_decl(name, size, fmt) \
 123 static ssize_t name##_show(struct esre_entry *entry, char *buf) \
 124 { \
 125         return sprintf(buf, fmt "\n", \
 126                        le##size##_to_cpu(entry->esre.esre1->name)); \
 127 } \
 128 \
 129 static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400)
 130
 131 esre_attr_decl(fw_type, 32, "%u");
 132 esre_attr_decl(fw_version, 32, "%u");
 133 esre_attr_decl(lowest_supported_fw_version, 32, "%u");
 134 esre_attr_decl(capsule_flags, 32, "0x%x");
 135 esre_attr_decl(last_attempt_version, 32, "%u");
 136 esre_attr_decl(last_attempt_status, 32, "%u");
 137
 138 static struct attribute *esre1_attrs[] = {
 139         &esre_fw_class.attr,
 140         &esre_fw_type.attr,
 141         &esre_fw_version.attr,
 142         &esre_lowest_supported_fw_version.attr,
 143         &esre_capsule_flags.attr,
 144         &esre_last_attempt_version.attr,
 145         &esre_last_attempt_status.attr,
 146         NULL
 147 };
 148 static void esre_release(struct kobject *kobj)
 149 {
 150         struct esre_entry *entry = to_entry(kobj);
 151
 152         list_del(&entry->list);
 153         kfree(entry);
 154 }
 155
 156 static struct kobj_type esre1_ktype = {
 157         .release = esre_release,
 158         .sysfs_ops = &esre_attr_ops,
 159         .default_attrs = esre1_attrs,
 160 };
 161
 162
 163 static struct kobject *esrt_kobj;
 164 static struct kset *esrt_kset;
 165
 166 static int esre_create_sysfs_entry(void *esre, int entry_num)
 167 {
 168         struct esre_entry *entry;
 169
 170         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 171         if (!entry)
 172                 return -ENOMEM;
 173
 174         entry->kobj.kset = esrt_kset;
 175
 176         if (esrt->fw_resource_version == 1) {
 177                 int rc = 0;
 178
 179                 entry->esre.esre1 = esre;
 180                 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
 181                                           "entry%d", entry_num);
 182                 if (rc) {
 183                         kfree(entry);
 184                         return rc;
 185                 }
 186         }
 187
 188         list_add_tail(&entry->list, &entry_list);
 189         return 0;
 190 }
 191
 192 /* support for displaying ESRT fields at the top level */
 193 #define esrt_attr_decl(name, size, fmt) \
 194 static ssize_t name##_show(struct kobject *kobj, \
 195                                   struct kobj_attribute *attr, char *buf)\
 196 { \
 197         return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
 198 } \
 199 \
 200 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400)
 201
 202 esrt_attr_decl(fw_resource_count, 32, "%u");
 203 esrt_attr_decl(fw_resource_count_max, 32, "%u");
 204 esrt_attr_decl(fw_resource_version, 64, "%llu");
 205
 206 static struct attribute *esrt_attrs[] = {
 207         &esrt_fw_resource_count.attr,
 208         &esrt_fw_resource_count_max.attr,
 209         &esrt_fw_resource_version.attr,
 210         NULL,
 211 };
 212
 213 static inline int esrt_table_exists(void)
 214 {
 215         if (!efi_enabled(EFI_CONFIG_TABLES))
 216                 return 0;
 217         if (efi.esrt == EFI_INVALID_TABLE_ADDR)
 218                 return 0;
 219         return 1;
 220 }
 221
 222 static umode_t esrt_attr_is_visible(struct kobject *kobj,
 223                                     struct attribute *attr, int n)
 224 {
 225         if (!esrt_table_exists())
 226                 return 0;
 227         return attr->mode;
 228 }
 229
 230 static const struct attribute_group esrt_attr_group = {
 231         .attrs = esrt_attrs,
 232         .is_visible = esrt_attr_is_visible,
 233 };
 234
 235 /*
 236  * remap the table, validate it, mark it reserved and unmap it.
 237  */
 238 void __init efi_esrt_init(void)
 239 {
 240         void *va;
 241         struct efi_system_resource_table tmpesrt;
 242         struct efi_system_resource_entry_v1 *v1_entries;
 243         size_t size, max, entry_size, entries_size;
 244         efi_memory_desc_t md;
 245         int rc;
 246         phys_addr_t end;
 247
 248         pr_debug("esrt-init: loading.\n");
 249         if (!esrt_table_exists())
 250                 return;
 251
 252         rc = efi_mem_desc_lookup(efi.esrt, &md);
 253         if (rc < 0) {
 254                 pr_warn("ESRT header is not in the memory map.\n");
 255                 return;
 256         }
 257
 258         max = efi_mem_desc_end(&md);
 259         if (max < efi.esrt) {
 260                 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n",
 261                        (void *)efi.esrt, (void *)max);
 262                 return;
 263         }
 264
 265         size = sizeof(*esrt);
 266         max -= efi.esrt;
 267
 268         if (max < size) {
 269                 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n",
 270                        size, max);
 271                 return;
 272         }
 273
 274         va = early_memremap(efi.esrt, size);
 275         if (!va) {
 276                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 277                        size);
 278                 return;
 279         }
 280
 281         memcpy(&tmpesrt, va, sizeof(tmpesrt));
 282
 283         if (tmpesrt.fw_resource_version == 1) {
 284                 entry_size = sizeof (*v1_entries);
 285         } else {
 286                 pr_err("Unsupported ESRT version %lld.\n",
 287                        tmpesrt.fw_resource_version);
 288                 return;
 289         }
 290
 291         if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
 292                 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
 293                        max - size, entry_size);
 294                 goto err_memunmap;
 295         }
 296
 297         /*
 298          * The format doesn't really give us any boundary to test here,
 299          * so I'm making up 128 as the max number of individually updatable
 300          * components we support.
 301          * 128 should be pretty excessive, but there's still some chance
 302          * somebody will do that someday and we'll need to raise this.
 303          */
 304         if (tmpesrt.fw_resource_count > 128) {
 305                 pr_err("ESRT says fw_resource_count has very large value %d.\n",
 306                        tmpesrt.fw_resource_count);
 307                 goto err_memunmap;
 308         }
 309
 310         /*
 311          * We know it can't be larger than N * sizeof() here, and N is limited
 312          * by the previous test to a small number, so there's no overflow.
 313          */
 314         entries_size = tmpesrt.fw_resource_count * entry_size;
 315         if (max < size + entries_size) {
 316                 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
 317                        size, max);
 318                 goto err_memunmap;
 319         }
 320
 321         /* remap it with our (plausible) new pages */
 322         early_memunmap(va, size);
 323         size += entries_size;
 324         va = early_memremap(efi.esrt, size);
 325         if (!va) {
 326                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 327                        size);
 328                 return;
 329         }
 330
 331         esrt_data = (phys_addr_t)efi.esrt;
 332         esrt_data_size = size;
 333
 334         end = esrt_data + size;
 335         pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
 336         efi_mem_reserve(esrt_data, esrt_data_size);
 337
 338         pr_debug("esrt-init: loaded.\n");
 339 err_memunmap:
 340         early_memunmap(va, size);
 341 }
 342
 343 static int __init register_entries(void)
 344 {
 345         struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
 346         int i, rc;
 347
 348         if (!esrt_table_exists())
 349                 return 0;
 350
 351         for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
 352                 void *esre = NULL;
 353                 if (esrt->fw_resource_version == 1) {
 354                         esre = &v1_entries[i];
 355                 } else {
 356                         pr_err("Unsupported ESRT version %lld.\n",
 357                                esrt->fw_resource_version);
 358                         return -EINVAL;
 359                 }
 360
 361                 rc = esre_create_sysfs_entry(esre, i);
 362                 if (rc < 0) {
 363                         pr_err("ESRT entry creation failed with error %d.\n",
 364                                rc);
 365                         return rc;
 366                 }
 367         }
 368         return 0;
 369 }
 370
 371 static void cleanup_entry_list(void)
 372 {
 373         struct esre_entry *entry, *next;
 374
 375         list_for_each_entry_safe(entry, next, &entry_list, list) {
 376                 kobject_put(&entry->kobj);
 377         }
 378 }
 379
 380 static int __init esrt_sysfs_init(void)
 381 {
 382         int error;
 383
 384         pr_debug("esrt-sysfs: loading.\n");
 385         if (!esrt_data || !esrt_data_size)
 386                 return -ENOSYS;
 387
 388         esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
 389         if (!esrt) {
 390                 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data,
 391                        esrt_data_size);
 392                 return -ENOMEM;
 393         }
 394
 395         esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
 396         if (!esrt_kobj) {
 397                 pr_err("Firmware table registration failed.\n");
 398                 error = -ENOMEM;
 399                 goto err;
 400         }
 401
 402         error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
 403         if (error) {
 404                 pr_err("Sysfs attribute export failed with error %d.\n",
 405                        error);
 406                 goto err_remove_esrt;
 407         }
 408
 409         esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
 410         if (!esrt_kset) {
 411                 pr_err("kset creation failed.\n");
 412                 error = -ENOMEM;
 413                 goto err_remove_group;
 414         }
 415
 416         error = register_entries();
 417         if (error)
 418                 goto err_cleanup_list;
 419
 420         pr_debug("esrt-sysfs: loaded.\n");
 421
 422         return 0;
 423 err_cleanup_list:
 424         cleanup_entry_list();
 425         kset_unregister(esrt_kset);
 426 err_remove_group:
 427         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 428 err_remove_esrt:
 429         kobject_put(esrt_kobj);
 430 err:
 431         memunmap(esrt);
 432         esrt = NULL;
 433         return error;
 434 }
 435 device_initcall(esrt_sysfs_init);
 436
 437 /*
 438 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
 439 MODULE_DESCRIPTION("EFI System Resource Table support");
 440 MODULE_LICENSE("GPL");
 441 */