drivers/firmware/efi/esrt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * esrt.c
   4  *
   5  * This module exports EFI System Resource Table (ESRT) entries into userspace
   6  * through the sysfs file system. The ESRT provides a read-only catalog of
   7  * system components for which the system accepts firmware upgrades via UEFI's
   8  * "Capsule Update" feature. This module allows userland utilities to evaluate
   9  * what firmware updates can be applied to this system, and potentially arrange
  10  * for those updates to occur.
  11  *
  12  * Data is currently found below /sys/firmware/efi/esrt/...
  13  */
  14 #define pr_fmt(fmt) "esrt: " fmt
  15
  16 #include <linux/capability.h>
  17 #include <linux/device.h>
  18 #include <linux/efi.h>
  19 #include <linux/init.h>
  20 #include <linux/io.h>
  21 #include <linux/kernel.h>
  22 #include <linux/kobject.h>
  23 #include <linux/list.h>
  24 #include <linux/memblock.h>
  25 #include <linux/slab.h>
  26 #include <linux/types.h>
  27
  28 #include <asm/io.h>
  29 #include <asm/early_ioremap.h>
  30
  31 struct efi_system_resource_entry_v1 {
  32         efi_guid_t      fw_class;
  33         u32             fw_type;
  34         u32             fw_version;
  35         u32             lowest_supported_fw_version;
  36         u32             capsule_flags;
  37         u32             last_attempt_version;
  38         u32             last_attempt_status;
  39 };
  40
  41 /*
  42  * _count and _version are what they seem like.  _max is actually just
  43  * accounting info for the firmware when creating the table; it should never
  44  * have been exposed to us.  To wit, the spec says:
  45  * The maximum number of resource array entries that can be within the
  46  * table without reallocating the table, must not be zero.
  47  * Since there's no guidance about what that means in terms of memory layout,
  48  * it means nothing to us.
  49  */
  50 struct efi_system_resource_table {
  51         u32     fw_resource_count;
  52         u32     fw_resource_count_max;
  53         u64     fw_resource_version;
  54         u8      entries[];
  55 };
  56
  57 static phys_addr_t esrt_data;
  58 static size_t esrt_data_size;
  59
  60 static struct efi_system_resource_table *esrt;
  61
  62 struct esre_entry {
  63         union {
  64                 struct efi_system_resource_entry_v1 *esre1;
  65         } esre;
  66
  67         struct kobject kobj;
  68         struct list_head list;
  69 };
  70
  71 /* global list of esre_entry. */
  72 static LIST_HEAD(entry_list);
  73
  74 /* entry attribute */
  75 struct esre_attribute {
  76         struct attribute attr;
  77         ssize_t (*show)(struct esre_entry *entry, char *buf);
  78         ssize_t (*store)(struct esre_entry *entry,
  79                          const char *buf, size_t count);
  80 };
  81
  82 static struct esre_entry *to_entry(struct kobject *kobj)
  83 {
  84         return container_of(kobj, struct esre_entry, kobj);
  85 }
  86
  87 static struct esre_attribute *to_attr(struct attribute *attr)
  88 {
  89         return container_of(attr, struct esre_attribute, attr);
  90 }
  91
  92 static ssize_t esre_attr_show(struct kobject *kobj,
  93                               struct attribute *_attr, char *buf)
  94 {
  95         struct esre_entry *entry = to_entry(kobj);
  96         struct esre_attribute *attr = to_attr(_attr);
  97
  98         return attr->show(entry, buf);
  99 }
 100
 101 static const struct sysfs_ops esre_attr_ops = {
 102         .show = esre_attr_show,
 103 };
 104
 105 /* Generic ESRT Entry ("ESRE") support. */
 106 static ssize_t fw_class_show(struct esre_entry *entry, char *buf)
 107 {
 108         char *str = buf;
 109
 110         efi_guid_to_str(&entry->esre.esre1->fw_class, str);
 111         str += strlen(str);
 112         str += sprintf(str, "\n");
 113
 114         return str - buf;
 115 }
 116
 117 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400);
 118
 119 #define esre_attr_decl(name, size, fmt) \
 120 static ssize_t name##_show(struct esre_entry *entry, char *buf) \
 121 { \
 122         return sprintf(buf, fmt "\n", \
 123                        le##size##_to_cpu(entry->esre.esre1->name)); \
 124 } \
 125 \
 126 static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400)
 127
 128 esre_attr_decl(fw_type, 32, "%u");
 129 esre_attr_decl(fw_version, 32, "%u");
 130 esre_attr_decl(lowest_supported_fw_version, 32, "%u");
 131 esre_attr_decl(capsule_flags, 32, "0x%x");
 132 esre_attr_decl(last_attempt_version, 32, "%u");
 133 esre_attr_decl(last_attempt_status, 32, "%u");
 134
 135 static struct attribute *esre1_attrs[] = {
 136         &esre_fw_class.attr,
 137         &esre_fw_type.attr,
 138         &esre_fw_version.attr,
 139         &esre_lowest_supported_fw_version.attr,
 140         &esre_capsule_flags.attr,
 141         &esre_last_attempt_version.attr,
 142         &esre_last_attempt_status.attr,
 143         NULL
 144 };
 145 ATTRIBUTE_GROUPS(esre1);
 146
 147 static void esre_release(struct kobject *kobj)
 148 {
 149         struct esre_entry *entry = to_entry(kobj);
 150
 151         list_del(&entry->list);
 152         kfree(entry);
 153 }
 154
 155 static const struct kobj_type esre1_ktype = {
 156         .release = esre_release,
 157         .sysfs_ops = &esre_attr_ops,
 158         .default_groups = esre1_groups,
 159 };
 160
 161
 162 static struct kobject *esrt_kobj;
 163 static struct kset *esrt_kset;
 164
 165 static int esre_create_sysfs_entry(void *esre, int entry_num)
 166 {
 167         struct esre_entry *entry;
 168
 169         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 170         if (!entry)
 171                 return -ENOMEM;
 172
 173         entry->kobj.kset = esrt_kset;
 174
 175         if (esrt->fw_resource_version == 1) {
 176                 int rc = 0;
 177
 178                 entry->esre.esre1 = esre;
 179                 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
 180                                           "entry%d", entry_num);
 181                 if (rc) {
 182                         kobject_put(&entry->kobj);
 183                         return rc;
 184                 }
 185         }
 186
 187         list_add_tail(&entry->list, &entry_list);
 188         return 0;
 189 }
 190
 191 /* support for displaying ESRT fields at the top level */
 192 #define esrt_attr_decl(name, size, fmt) \
 193 static ssize_t name##_show(struct kobject *kobj, \
 194                                   struct kobj_attribute *attr, char *buf)\
 195 { \
 196         return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
 197 } \
 198 \
 199 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400)
 200
 201 esrt_attr_decl(fw_resource_count, 32, "%u");
 202 esrt_attr_decl(fw_resource_count_max, 32, "%u");
 203 esrt_attr_decl(fw_resource_version, 64, "%llu");
 204
 205 static struct attribute *esrt_attrs[] = {
 206         &esrt_fw_resource_count.attr,
 207         &esrt_fw_resource_count_max.attr,
 208         &esrt_fw_resource_version.attr,
 209         NULL,
 210 };
 211
 212 static inline int esrt_table_exists(void)
 213 {
 214         if (!efi_enabled(EFI_CONFIG_TABLES))
 215                 return 0;
 216         if (efi.esrt == EFI_INVALID_TABLE_ADDR)
 217                 return 0;
 218         return 1;
 219 }
 220
 221 static umode_t esrt_attr_is_visible(struct kobject *kobj,
 222                                     struct attribute *attr, int n)
 223 {
 224         if (!esrt_table_exists())
 225                 return 0;
 226         return attr->mode;
 227 }
 228
 229 static const struct attribute_group esrt_attr_group = {
 230         .attrs = esrt_attrs,
 231         .is_visible = esrt_attr_is_visible,
 232 };
 233
 234 /*
 235  * remap the table, validate it, mark it reserved and unmap it.
 236  */
 237 void __init efi_esrt_init(void)
 238 {
 239         void *va;
 240         struct efi_system_resource_table tmpesrt;
 241         size_t size, max, entry_size, entries_size;
 242         efi_memory_desc_t md;
 243         int rc;
 244         phys_addr_t end;
 245
 246         if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT))
 247                 return;
 248
 249         pr_debug("esrt-init: loading.\n");
 250         if (!esrt_table_exists())
 251                 return;
 252
 253         rc = efi_mem_desc_lookup(efi.esrt, &md);
 254         if (rc < 0 ||
 255             (!(md.attribute & EFI_MEMORY_RUNTIME) &&
 256              md.type != EFI_BOOT_SERVICES_DATA &&
 257              md.type != EFI_RUNTIME_SERVICES_DATA &&
 258              md.type != EFI_ACPI_RECLAIM_MEMORY &&
 259              md.type != EFI_ACPI_MEMORY_NVS)) {
 260                 pr_warn("ESRT header is not in the memory map.\n");
 261                 return;
 262         }
 263
 264         max = efi_mem_desc_end(&md) - efi.esrt;
 265         size = sizeof(*esrt);
 266
 267         if (max < size) {
 268                 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n",
 269                        size, max);
 270                 return;
 271         }
 272
 273         va = early_memremap(efi.esrt, size);
 274         if (!va) {
 275                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 276                        size);
 277                 return;
 278         }
 279
 280         memcpy(&tmpesrt, va, sizeof(tmpesrt));
 281         early_memunmap(va, size);
 282
 283         if (tmpesrt.fw_resource_version != 1) {
 284                 pr_err("Unsupported ESRT version %lld.\n",
 285                        tmpesrt.fw_resource_version);
 286                 return;
 287         }
 288
 289         entry_size = sizeof(struct efi_system_resource_entry_v1);
 290         if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
 291                 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
 292                        max - size, entry_size);
 293                 return;
 294         }
 295
 296         /*
 297          * The format doesn't really give us any boundary to test here,
 298          * so I'm making up 128 as the max number of individually updatable
 299          * components we support.
 300          * 128 should be pretty excessive, but there's still some chance
 301          * somebody will do that someday and we'll need to raise this.
 302          */
 303         if (tmpesrt.fw_resource_count > 128) {
 304                 pr_err("ESRT says fw_resource_count has very large value %d.\n",
 305                        tmpesrt.fw_resource_count);
 306                 return;
 307         }
 308
 309         /*
 310          * We know it can't be larger than N * sizeof() here, and N is limited
 311          * by the previous test to a small number, so there's no overflow.
 312          */
 313         entries_size = tmpesrt.fw_resource_count * entry_size;
 314         if (max < size + entries_size) {
 315                 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
 316                        size, max);
 317                 return;
 318         }
 319
 320         size += entries_size;
 321
 322         esrt_data = (phys_addr_t)efi.esrt;
 323         esrt_data_size = size;
 324
 325         end = esrt_data + size;
 326         pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
 327         if (md.type == EFI_BOOT_SERVICES_DATA)
 328                 efi_mem_reserve(esrt_data, esrt_data_size);
 329
 330         pr_debug("esrt-init: loaded.\n");
 331 }
 332
 333 static int __init register_entries(void)
 334 {
 335         struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
 336         int i, rc;
 337
 338         if (!esrt_table_exists())
 339                 return 0;
 340
 341         for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
 342                 void *esre = NULL;
 343                 if (esrt->fw_resource_version == 1) {
 344                         esre = &v1_entries[i];
 345                 } else {
 346                         pr_err("Unsupported ESRT version %lld.\n",
 347                                esrt->fw_resource_version);
 348                         return -EINVAL;
 349                 }
 350
 351                 rc = esre_create_sysfs_entry(esre, i);
 352                 if (rc < 0) {
 353                         pr_err("ESRT entry creation failed with error %d.\n",
 354                                rc);
 355                         return rc;
 356                 }
 357         }
 358         return 0;
 359 }
 360
 361 static void cleanup_entry_list(void)
 362 {
 363         struct esre_entry *entry, *next;
 364
 365         list_for_each_entry_safe(entry, next, &entry_list, list) {
 366                 kobject_put(&entry->kobj);
 367         }
 368 }
 369
 370 static int __init esrt_sysfs_init(void)
 371 {
 372         int error;
 373
 374         pr_debug("esrt-sysfs: loading.\n");
 375         if (!esrt_data || !esrt_data_size)
 376                 return -ENOSYS;
 377
 378         esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
 379         if (!esrt) {
 380                 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data,
 381                        esrt_data_size);
 382                 return -ENOMEM;
 383         }
 384
 385         esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
 386         if (!esrt_kobj) {
 387                 pr_err("Firmware table registration failed.\n");
 388                 error = -ENOMEM;
 389                 goto err;
 390         }
 391
 392         error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
 393         if (error) {
 394                 pr_err("Sysfs attribute export failed with error %d.\n",
 395                        error);
 396                 goto err_remove_esrt;
 397         }
 398
 399         esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
 400         if (!esrt_kset) {
 401                 pr_err("kset creation failed.\n");
 402                 error = -ENOMEM;
 403                 goto err_remove_group;
 404         }
 405
 406         error = register_entries();
 407         if (error)
 408                 goto err_cleanup_list;
 409
 410         pr_debug("esrt-sysfs: loaded.\n");
 411
 412         return 0;
 413 err_cleanup_list:
 414         cleanup_entry_list();
 415         kset_unregister(esrt_kset);
 416 err_remove_group:
 417         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 418 err_remove_esrt:
 419         kobject_put(esrt_kobj);
 420 err:
 421         memunmap(esrt);
 422         esrt = NULL;
 423         return error;
 424 }
 425 device_initcall(esrt_sysfs_init);
 426
 427 /*
 428 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
 429 MODULE_DESCRIPTION("EFI System Resource Table support");
 430 MODULE_LICENSE("GPL");
 431 */