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 };
  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         return attr->show(entry, buf);
  97 }
  98
  99 static const struct sysfs_ops esre_attr_ops = {
 100         .show = esre_attr_show,
 101 };
 102
 103 /* Generic ESRT Entry ("ESRE") support. */
 104 static ssize_t fw_class_show(struct esre_entry *entry, char *buf)
 105 {
 106         char *str = buf;
 107
 108         efi_guid_to_str(&entry->esre.esre1->fw_class, str);
 109         str += strlen(str);
 110         str += sprintf(str, "\n");
 111
 112         return str - buf;
 113 }
 114
 115 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400);
 116
 117 #define esre_attr_decl(name, size, fmt) \
 118 static ssize_t name##_show(struct esre_entry *entry, char *buf) \
 119 { \
 120         return sprintf(buf, fmt "\n", \
 121                        le##size##_to_cpu(entry->esre.esre1->name)); \
 122 } \
 123 \
 124 static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400)
 125
 126 esre_attr_decl(fw_type, 32, "%u");
 127 esre_attr_decl(fw_version, 32, "%u");
 128 esre_attr_decl(lowest_supported_fw_version, 32, "%u");
 129 esre_attr_decl(capsule_flags, 32, "0x%x");
 130 esre_attr_decl(last_attempt_version, 32, "%u");
 131 esre_attr_decl(last_attempt_status, 32, "%u");
 132
 133 static struct attribute *esre1_attrs[] = {
 134         &esre_fw_class.attr,
 135         &esre_fw_type.attr,
 136         &esre_fw_version.attr,
 137         &esre_lowest_supported_fw_version.attr,
 138         &esre_capsule_flags.attr,
 139         &esre_last_attempt_version.attr,
 140         &esre_last_attempt_status.attr,
 141         NULL
 142 };
 143 ATTRIBUTE_GROUPS(esre1);
 144
 145 static void esre_release(struct kobject *kobj)
 146 {
 147         struct esre_entry *entry = to_entry(kobj);
 148
 149         list_del(&entry->list);
 150         kfree(entry);
 151 }
 152
 153 static const struct kobj_type esre1_ktype = {
 154         .release = esre_release,
 155         .sysfs_ops = &esre_attr_ops,
 156         .default_groups = esre1_groups,
 157 };
 158
 159
 160 static struct kobject *esrt_kobj;
 161 static struct kset *esrt_kset;
 162
 163 static int esre_create_sysfs_entry(void *esre, int entry_num)
 164 {
 165         struct esre_entry *entry;
 166
 167         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 168         if (!entry)
 169                 return -ENOMEM;
 170
 171         entry->kobj.kset = esrt_kset;
 172
 173         if (esrt->fw_resource_version == 1) {
 174                 int rc = 0;
 175
 176                 entry->esre.esre1 = esre;
 177                 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
 178                                           "entry%d", entry_num);
 179                 if (rc) {
 180                         kobject_put(&entry->kobj);
 181                         return rc;
 182                 }
 183         }
 184
 185         list_add_tail(&entry->list, &entry_list);
 186         return 0;
 187 }
 188
 189 /* support for displaying ESRT fields at the top level */
 190 #define esrt_attr_decl(name, size, fmt) \
 191 static ssize_t name##_show(struct kobject *kobj, \
 192                                   struct kobj_attribute *attr, char *buf)\
 193 { \
 194         return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
 195 } \
 196 \
 197 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400)
 198
 199 esrt_attr_decl(fw_resource_count, 32, "%u");
 200 esrt_attr_decl(fw_resource_count_max, 32, "%u");
 201 esrt_attr_decl(fw_resource_version, 64, "%llu");
 202
 203 static struct attribute *esrt_attrs[] = {
 204         &esrt_fw_resource_count.attr,
 205         &esrt_fw_resource_count_max.attr,
 206         &esrt_fw_resource_version.attr,
 207         NULL,
 208 };
 209
 210 static inline int esrt_table_exists(void)
 211 {
 212         if (!efi_enabled(EFI_CONFIG_TABLES))
 213                 return 0;
 214         if (efi.esrt == EFI_INVALID_TABLE_ADDR)
 215                 return 0;
 216         return 1;
 217 }
 218
 219 static umode_t esrt_attr_is_visible(struct kobject *kobj,
 220                                     struct attribute *attr, int n)
 221 {
 222         if (!esrt_table_exists())
 223                 return 0;
 224         return attr->mode;
 225 }
 226
 227 static const struct attribute_group esrt_attr_group = {
 228         .attrs = esrt_attrs,
 229         .is_visible = esrt_attr_is_visible,
 230 };
 231
 232 /*
 233  * remap the table, validate it, mark it reserved and unmap it.
 234  */
 235 void __init efi_esrt_init(void)
 236 {
 237         void *va;
 238         struct efi_system_resource_table tmpesrt;
 239         size_t size, max, entry_size, entries_size;
 240         efi_memory_desc_t md;
 241         int rc;
 242         phys_addr_t end;
 243
 244         if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT))
 245                 return;
 246
 247         pr_debug("esrt-init: loading.\n");
 248         if (!esrt_table_exists())
 249                 return;
 250
 251         rc = efi_mem_desc_lookup(efi.esrt, &md);
 252         if (rc < 0 ||
 253             (!(md.attribute & EFI_MEMORY_RUNTIME) &&
 254              md.type != EFI_BOOT_SERVICES_DATA &&
 255              md.type != EFI_RUNTIME_SERVICES_DATA &&
 256              md.type != EFI_ACPI_RECLAIM_MEMORY &&
 257              md.type != EFI_ACPI_MEMORY_NVS)) {
 258                 pr_warn("ESRT header is not in the memory map.\n");
 259                 return;
 260         }
 261
 262         max = efi_mem_desc_end(&md) - efi.esrt;
 263         size = sizeof(*esrt);
 264
 265         if (max < size) {
 266                 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n",
 267                        size, max);
 268                 return;
 269         }
 270
 271         va = early_memremap(efi.esrt, size);
 272         if (!va) {
 273                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 274                        size);
 275                 return;
 276         }
 277
 278         memcpy(&tmpesrt, va, sizeof(tmpesrt));
 279         early_memunmap(va, size);
 280
 281         if (tmpesrt.fw_resource_version != 1) {
 282                 pr_err("Unsupported ESRT version %lld.\n",
 283                        tmpesrt.fw_resource_version);
 284                 return;
 285         }
 286
 287         entry_size = sizeof(struct efi_system_resource_entry_v1);
 288         if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
 289                 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
 290                        max - size, entry_size);
 291                 return;
 292         }
 293
 294         /*
 295          * The format doesn't really give us any boundary to test here,
 296          * so I'm making up 128 as the max number of individually updatable
 297          * components we support.
 298          * 128 should be pretty excessive, but there's still some chance
 299          * somebody will do that someday and we'll need to raise this.
 300          */
 301         if (tmpesrt.fw_resource_count > 128) {
 302                 pr_err("ESRT says fw_resource_count has very large value %d.\n",
 303                        tmpesrt.fw_resource_count);
 304                 return;
 305         }
 306
 307         /*
 308          * We know it can't be larger than N * sizeof() here, and N is limited
 309          * by the previous test to a small number, so there's no overflow.
 310          */
 311         entries_size = tmpesrt.fw_resource_count * entry_size;
 312         if (max < size + entries_size) {
 313                 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
 314                        size, max);
 315                 return;
 316         }
 317
 318         size += entries_size;
 319
 320         esrt_data = (phys_addr_t)efi.esrt;
 321         esrt_data_size = size;
 322
 323         end = esrt_data + size;
 324         pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
 325         if (md.type == EFI_BOOT_SERVICES_DATA)
 326                 efi_mem_reserve(esrt_data, esrt_data_size);
 327
 328         pr_debug("esrt-init: loaded.\n");
 329 }
 330
 331 static int __init register_entries(void)
 332 {
 333         struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
 334         int i, rc;
 335
 336         if (!esrt_table_exists())
 337                 return 0;
 338
 339         for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
 340                 void *esre = NULL;
 341                 if (esrt->fw_resource_version == 1) {
 342                         esre = &v1_entries[i];
 343                 } else {
 344                         pr_err("Unsupported ESRT version %lld.\n",
 345                                esrt->fw_resource_version);
 346                         return -EINVAL;
 347                 }
 348
 349                 rc = esre_create_sysfs_entry(esre, i);
 350                 if (rc < 0) {
 351                         pr_err("ESRT entry creation failed with error %d.\n",
 352                                rc);
 353                         return rc;
 354                 }
 355         }
 356         return 0;
 357 }
 358
 359 static void cleanup_entry_list(void)
 360 {
 361         struct esre_entry *entry, *next;
 362
 363         list_for_each_entry_safe(entry, next, &entry_list, list) {
 364                 kobject_put(&entry->kobj);
 365         }
 366 }
 367
 368 static int __init esrt_sysfs_init(void)
 369 {
 370         int error;
 371
 372         pr_debug("esrt-sysfs: loading.\n");
 373         if (!esrt_data || !esrt_data_size)
 374                 return -ENOSYS;
 375
 376         esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
 377         if (!esrt) {
 378                 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data,
 379                        esrt_data_size);
 380                 return -ENOMEM;
 381         }
 382
 383         esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
 384         if (!esrt_kobj) {
 385                 pr_err("Firmware table registration failed.\n");
 386                 error = -ENOMEM;
 387                 goto err;
 388         }
 389
 390         error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
 391         if (error) {
 392                 pr_err("Sysfs attribute export failed with error %d.\n",
 393                        error);
 394                 goto err_remove_esrt;
 395         }
 396
 397         esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
 398         if (!esrt_kset) {
 399                 pr_err("kset creation failed.\n");
 400                 error = -ENOMEM;
 401                 goto err_remove_group;
 402         }
 403
 404         error = register_entries();
 405         if (error)
 406                 goto err_cleanup_list;
 407
 408         pr_debug("esrt-sysfs: loaded.\n");
 409
 410         return 0;
 411 err_cleanup_list:
 412         cleanup_entry_list();
 413         kset_unregister(esrt_kset);
 414 err_remove_group:
 415         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 416 err_remove_esrt:
 417         kobject_put(esrt_kobj);
 418 err:
 419         memunmap(esrt);
 420         esrt = NULL;
 421         return error;
 422 }
 423 device_initcall(esrt_sysfs_init);
 424
 425 /*
 426 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
 427 MODULE_DESCRIPTION("EFI System Resource Table support");
 428 MODULE_LICENSE("GPL");
 429 */