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/kernel.h>
  20 #include <linux/kobject.h>
  21 #include <linux/list.h>
  22 #include <linux/memblock.h>
  23 #include <linux/slab.h>
  24 #include <linux/types.h>
  25
  26 #include <asm/io.h>
  27 #include <asm/early_ioremap.h>
  28
  29 struct efi_system_resource_entry_v1 {
  30         efi_guid_t      fw_class;
  31         u32             fw_type;
  32         u32             fw_version;
  33         u32             lowest_supported_fw_version;
  34         u32             capsule_flags;
  35         u32             last_attempt_version;
  36         u32             last_attempt_status;
  37 };
  38
  39 /*
  40  * _count and _version are what they seem like.  _max is actually just
  41  * accounting info for the firmware when creating the table; it should never
  42  * have been exposed to us.  To wit, the spec says:
  43  * The maximum number of resource array entries that can be within the
  44  * table without reallocating the table, must not be zero.
  45  * Since there's no guidance about what that means in terms of memory layout,
  46  * it means nothing to us.
  47  */
  48 struct efi_system_resource_table {
  49         u32     fw_resource_count;
  50         u32     fw_resource_count_max;
  51         u64     fw_resource_version;
  52         u8      entries[];
  53 };
  54
  55 static phys_addr_t esrt_data;
  56 static size_t esrt_data_size;
  57
  58 static struct efi_system_resource_table *esrt;
  59
  60 struct esre_entry {
  61         union {
  62                 struct efi_system_resource_entry_v1 *esre1;
  63         } esre;
  64
  65         struct kobject kobj;
  66         struct list_head list;
  67 };
  68
  69 /* global list of esre_entry. */
  70 static LIST_HEAD(entry_list);
  71
  72 /* entry attribute */
  73 struct esre_attribute {
  74         struct attribute attr;
  75         ssize_t (*show)(struct esre_entry *entry, char *buf);
  76         ssize_t (*store)(struct esre_entry *entry,
  77                          const char *buf, size_t count);
  78 };
  79
  80 static struct esre_entry *to_entry(struct kobject *kobj)
  81 {
  82         return container_of(kobj, struct esre_entry, kobj);
  83 }
  84
  85 static struct esre_attribute *to_attr(struct attribute *attr)
  86 {
  87         return container_of(attr, struct esre_attribute, attr);
  88 }
  89
  90 static ssize_t esre_attr_show(struct kobject *kobj,
  91                               struct attribute *_attr, char *buf)
  92 {
  93         struct esre_entry *entry = to_entry(kobj);
  94         struct esre_attribute *attr = to_attr(_attr);
  95
  96         /* Don't tell normal users what firmware versions we've got... */
  97         if (!capable(CAP_SYS_ADMIN))
  98                 return -EACCES;
  99
 100         return attr->show(entry, buf);
 101 }
 102
 103 static const struct sysfs_ops esre_attr_ops = {
 104         .show = esre_attr_show,
 105 };
 106
 107 /* Generic ESRT Entry ("ESRE") support. */
 108 static ssize_t esre_fw_class_show(struct esre_entry *entry, char *buf)
 109 {
 110         char *str = buf;
 111
 112         efi_guid_to_str(&entry->esre.esre1->fw_class, str);
 113         str += strlen(str);
 114         str += sprintf(str, "\n");
 115
 116         return str - buf;
 117 }
 118
 119 static struct esre_attribute esre_fw_class = __ATTR(fw_class, 0400,
 120         esre_fw_class_show, NULL);
 121
 122 #define esre_attr_decl(name, size, fmt) \
 123 static ssize_t esre_##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(name, 0400, \
 130         esre_##name##_show, NULL)
 131
 132 esre_attr_decl(fw_type, 32, "%u");
 133 esre_attr_decl(fw_version, 32, "%u");
 134 esre_attr_decl(lowest_supported_fw_version, 32, "%u");
 135 esre_attr_decl(capsule_flags, 32, "0x%x");
 136 esre_attr_decl(last_attempt_version, 32, "%u");
 137 esre_attr_decl(last_attempt_status, 32, "%u");
 138
 139 static struct attribute *esre1_attrs[] = {
 140         &esre_fw_class.attr,
 141         &esre_fw_type.attr,
 142         &esre_fw_version.attr,
 143         &esre_lowest_supported_fw_version.attr,
 144         &esre_capsule_flags.attr,
 145         &esre_last_attempt_version.attr,
 146         &esre_last_attempt_status.attr,
 147         NULL
 148 };
 149 static void esre_release(struct kobject *kobj)
 150 {
 151         struct esre_entry *entry = to_entry(kobj);
 152
 153         list_del(&entry->list);
 154         kfree(entry);
 155 }
 156
 157 static struct kobj_type esre1_ktype = {
 158         .release = esre_release,
 159         .sysfs_ops = &esre_attr_ops,
 160         .default_attrs = esre1_attrs,
 161 };
 162
 163
 164 static struct kobject *esrt_kobj;
 165 static struct kset *esrt_kset;
 166
 167 static int esre_create_sysfs_entry(void *esre, int entry_num)
 168 {
 169         struct esre_entry *entry;
 170         char name[20];
 171
 172         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 173         if (!entry)
 174                 return -ENOMEM;
 175
 176         sprintf(name, "entry%d", entry_num);
 177
 178         entry->kobj.kset = esrt_kset;
 179
 180         if (esrt->fw_resource_version == 1) {
 181                 int rc = 0;
 182
 183                 entry->esre.esre1 = esre;
 184                 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
 185                                           "%s", name);
 186                 if (rc) {
 187                         kfree(entry);
 188                         return rc;
 189                 }
 190         }
 191
 192         list_add_tail(&entry->list, &entry_list);
 193         return 0;
 194 }
 195
 196 /* support for displaying ESRT fields at the top level */
 197 #define esrt_attr_decl(name, size, fmt) \
 198 static ssize_t esrt_##name##_show(struct kobject *kobj, \
 199                                   struct kobj_attribute *attr, char *buf)\
 200 { \
 201         return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
 202 } \
 203 \
 204 static struct kobj_attribute esrt_##name = __ATTR(name, 0400, \
 205         esrt_##name##_show, NULL)
 206
 207 esrt_attr_decl(fw_resource_count, 32, "%u");
 208 esrt_attr_decl(fw_resource_count_max, 32, "%u");
 209 esrt_attr_decl(fw_resource_version, 64, "%llu");
 210
 211 static struct attribute *esrt_attrs[] = {
 212         &esrt_fw_resource_count.attr,
 213         &esrt_fw_resource_count_max.attr,
 214         &esrt_fw_resource_version.attr,
 215         NULL,
 216 };
 217
 218 static inline int esrt_table_exists(void)
 219 {
 220         if (!efi_enabled(EFI_CONFIG_TABLES))
 221                 return 0;
 222         if (efi.esrt == EFI_INVALID_TABLE_ADDR)
 223                 return 0;
 224         return 1;
 225 }
 226
 227 static umode_t esrt_attr_is_visible(struct kobject *kobj,
 228                                     struct attribute *attr, int n)
 229 {
 230         if (!esrt_table_exists())
 231                 return 0;
 232         return attr->mode;
 233 }
 234
 235 static struct attribute_group esrt_attr_group = {
 236         .attrs = esrt_attrs,
 237         .is_visible = esrt_attr_is_visible,
 238 };
 239
 240 /*
 241  * remap the table, copy it to kmalloced pages, and unmap it.
 242  */
 243 void __init efi_esrt_init(void)
 244 {
 245         void *va;
 246         struct efi_system_resource_table tmpesrt;
 247         struct efi_system_resource_entry_v1 *v1_entries;
 248         size_t size, max, entry_size, entries_size;
 249         efi_memory_desc_t md;
 250         int rc;
 251         phys_addr_t end;
 252
 253         pr_debug("esrt-init: loading.\n");
 254         if (!esrt_table_exists())
 255                 return;
 256
 257         rc = efi_mem_desc_lookup(efi.esrt, &md);
 258         if (rc < 0) {
 259                 pr_err("ESRT header is not in the memory map.\n");
 260                 return;
 261         }
 262
 263         max = efi_mem_desc_end(&md);
 264         if (max < efi.esrt) {
 265                 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n",
 266                        (void *)efi.esrt, (void *)max);
 267                 return;
 268         }
 269
 270         size = sizeof(*esrt);
 271         max -= efi.esrt;
 272
 273         if (max < size) {
 274                 pr_err("ESRT header doen't fit on single memory map entry. (size: %zu max: %zu)\n",
 275                        size, max);
 276                 return;
 277         }
 278
 279         va = early_memremap(efi.esrt, size);
 280         if (!va) {
 281                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 282                        size);
 283                 return;
 284         }
 285
 286         memcpy(&tmpesrt, va, sizeof(tmpesrt));
 287
 288         if (tmpesrt.fw_resource_version == 1) {
 289                 entry_size = sizeof (*v1_entries);
 290         } else {
 291                 pr_err("Unsupported ESRT version %lld.\n",
 292                        tmpesrt.fw_resource_version);
 293                 return;
 294         }
 295
 296         if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
 297                 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
 298                        max - size, entry_size);
 299                 goto err_memunmap;
 300         }
 301
 302         /*
 303          * The format doesn't really give us any boundary to test here,
 304          * so I'm making up 128 as the max number of individually updatable
 305          * components we support.
 306          * 128 should be pretty excessive, but there's still some chance
 307          * somebody will do that someday and we'll need to raise this.
 308          */
 309         if (tmpesrt.fw_resource_count > 128) {
 310                 pr_err("ESRT says fw_resource_count has very large value %d.\n",
 311                        tmpesrt.fw_resource_count);
 312                 goto err_memunmap;
 313         }
 314
 315         /*
 316          * We know it can't be larger than N * sizeof() here, and N is limited
 317          * by the previous test to a small number, so there's no overflow.
 318          */
 319         entries_size = tmpesrt.fw_resource_count * entry_size;
 320         if (max < size + entries_size) {
 321                 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
 322                        size, max);
 323                 goto err_memunmap;
 324         }
 325
 326         /* remap it with our (plausible) new pages */
 327         early_memunmap(va, size);
 328         size += entries_size;
 329         va = early_memremap(efi.esrt, size);
 330         if (!va) {
 331                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 332                        size);
 333                 return;
 334         }
 335
 336         esrt_data = (phys_addr_t)efi.esrt;
 337         esrt_data_size = size;
 338
 339         end = esrt_data + size;
 340         pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
 341         memblock_reserve(esrt_data, esrt_data_size);
 342
 343         pr_debug("esrt-init: loaded.\n");
 344 err_memunmap:
 345         early_memunmap(va, size);
 346 }
 347
 348 static int __init register_entries(void)
 349 {
 350         struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
 351         int i, rc;
 352
 353         if (!esrt_table_exists())
 354                 return 0;
 355
 356         for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
 357                 void *esre = NULL;
 358                 if (esrt->fw_resource_version == 1) {
 359                         esre = &v1_entries[i];
 360                 } else {
 361                         pr_err("Unsupported ESRT version %lld.\n",
 362                                esrt->fw_resource_version);
 363                         return -EINVAL;
 364                 }
 365
 366                 rc = esre_create_sysfs_entry(esre, i);
 367                 if (rc < 0) {
 368                         pr_err("ESRT entry creation failed with error %d.\n",
 369                                rc);
 370                         return rc;
 371                 }
 372         }
 373         return 0;
 374 }
 375
 376 static void cleanup_entry_list(void)
 377 {
 378         struct esre_entry *entry, *next;
 379
 380         list_for_each_entry_safe(entry, next, &entry_list, list) {
 381                 kobject_put(&entry->kobj);
 382         }
 383 }
 384
 385 static int __init esrt_sysfs_init(void)
 386 {
 387         int error;
 388         struct efi_system_resource_table __iomem *ioesrt;
 389
 390         pr_debug("esrt-sysfs: loading.\n");
 391         if (!esrt_data || !esrt_data_size)
 392                 return -ENOSYS;
 393
 394         ioesrt = ioremap(esrt_data, esrt_data_size);
 395         if (!ioesrt) {
 396                 pr_err("ioremap(%pa, %zu) failed.\n", &esrt_data,
 397                        esrt_data_size);
 398                 return -ENOMEM;
 399         }
 400
 401         esrt = kmalloc(esrt_data_size, GFP_KERNEL);
 402         if (!esrt) {
 403                 pr_err("kmalloc failed. (wanted %zu bytes)\n", esrt_data_size);
 404                 iounmap(ioesrt);
 405                 return -ENOMEM;
 406         }
 407
 408         memcpy_fromio(esrt, ioesrt, esrt_data_size);
 409
 410         esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
 411         if (!esrt_kobj) {
 412                 pr_err("Firmware table registration failed.\n");
 413                 error = -ENOMEM;
 414                 goto err;
 415         }
 416
 417         error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
 418         if (error) {
 419                 pr_err("Sysfs attribute export failed with error %d.\n",
 420                        error);
 421                 goto err_remove_esrt;
 422         }
 423
 424         esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
 425         if (!esrt_kset) {
 426                 pr_err("kset creation failed.\n");
 427                 error = -ENOMEM;
 428                 goto err_remove_group;
 429         }
 430
 431         error = register_entries();
 432         if (error)
 433                 goto err_cleanup_list;
 434
 435         memblock_remove(esrt_data, esrt_data_size);
 436
 437         pr_debug("esrt-sysfs: loaded.\n");
 438
 439         return 0;
 440 err_cleanup_list:
 441         cleanup_entry_list();
 442         kset_unregister(esrt_kset);
 443 err_remove_group:
 444         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 445 err_remove_esrt:
 446         kobject_put(esrt_kobj);
 447 err:
 448         kfree(esrt);
 449         esrt = NULL;
 450         return error;
 451 }
 452 device_initcall(esrt_sysfs_init);
 453
 454 /*
 455 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
 456 MODULE_DESCRIPTION("EFI System Resource Table support");
 457 MODULE_LICENSE("GPL");
 458 */