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 esre_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(fw_class, 0400,
 121         esre_fw_class_show, NULL);
 122
 123 #define esre_attr_decl(name, size, fmt) \
 124 static ssize_t esre_##name##_show(struct esre_entry *entry, char *buf) \
 125 { \
 126         return sprintf(buf, fmt "\n", \
 127                        le##size##_to_cpu(entry->esre.esre1->name)); \
 128 } \
 129 \
 130 static struct esre_attribute esre_##name = __ATTR(name, 0400, \
 131         esre_##name##_show, NULL)
 132
 133 esre_attr_decl(fw_type, 32, "%u");
 134 esre_attr_decl(fw_version, 32, "%u");
 135 esre_attr_decl(lowest_supported_fw_version, 32, "%u");
 136 esre_attr_decl(capsule_flags, 32, "0x%x");
 137 esre_attr_decl(last_attempt_version, 32, "%u");
 138 esre_attr_decl(last_attempt_status, 32, "%u");
 139
 140 static struct attribute *esre1_attrs[] = {
 141         &esre_fw_class.attr,
 142         &esre_fw_type.attr,
 143         &esre_fw_version.attr,
 144         &esre_lowest_supported_fw_version.attr,
 145         &esre_capsule_flags.attr,
 146         &esre_last_attempt_version.attr,
 147         &esre_last_attempt_status.attr,
 148         NULL
 149 };
 150 static void esre_release(struct kobject *kobj)
 151 {
 152         struct esre_entry *entry = to_entry(kobj);
 153
 154         list_del(&entry->list);
 155         kfree(entry);
 156 }
 157
 158 static struct kobj_type esre1_ktype = {
 159         .release = esre_release,
 160         .sysfs_ops = &esre_attr_ops,
 161         .default_attrs = esre1_attrs,
 162 };
 163
 164
 165 static struct kobject *esrt_kobj;
 166 static struct kset *esrt_kset;
 167
 168 static int esre_create_sysfs_entry(void *esre, int entry_num)
 169 {
 170         struct esre_entry *entry;
 171
 172         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 173         if (!entry)
 174                 return -ENOMEM;
 175
 176         entry->kobj.kset = esrt_kset;
 177
 178         if (esrt->fw_resource_version == 1) {
 179                 int rc = 0;
 180
 181                 entry->esre.esre1 = esre;
 182                 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
 183                                           "entry%d", entry_num);
 184                 if (rc) {
 185                         kfree(entry);
 186                         return rc;
 187                 }
 188         }
 189
 190         list_add_tail(&entry->list, &entry_list);
 191         return 0;
 192 }
 193
 194 /* support for displaying ESRT fields at the top level */
 195 #define esrt_attr_decl(name, size, fmt) \
 196 static ssize_t esrt_##name##_show(struct kobject *kobj, \
 197                                   struct kobj_attribute *attr, char *buf)\
 198 { \
 199         return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
 200 } \
 201 \
 202 static struct kobj_attribute esrt_##name = __ATTR(name, 0400, \
 203         esrt_##name##_show, NULL)
 204
 205 esrt_attr_decl(fw_resource_count, 32, "%u");
 206 esrt_attr_decl(fw_resource_count_max, 32, "%u");
 207 esrt_attr_decl(fw_resource_version, 64, "%llu");
 208
 209 static struct attribute *esrt_attrs[] = {
 210         &esrt_fw_resource_count.attr,
 211         &esrt_fw_resource_count_max.attr,
 212         &esrt_fw_resource_version.attr,
 213         NULL,
 214 };
 215
 216 static inline int esrt_table_exists(void)
 217 {
 218         if (!efi_enabled(EFI_CONFIG_TABLES))
 219                 return 0;
 220         if (efi.esrt == EFI_INVALID_TABLE_ADDR)
 221                 return 0;
 222         return 1;
 223 }
 224
 225 static umode_t esrt_attr_is_visible(struct kobject *kobj,
 226                                     struct attribute *attr, int n)
 227 {
 228         if (!esrt_table_exists())
 229                 return 0;
 230         return attr->mode;
 231 }
 232
 233 static struct attribute_group esrt_attr_group = {
 234         .attrs = esrt_attrs,
 235         .is_visible = esrt_attr_is_visible,
 236 };
 237
 238 /*
 239  * remap the table, validate it, mark it reserved and unmap it.
 240  */
 241 void __init efi_esrt_init(void)
 242 {
 243         void *va;
 244         struct efi_system_resource_table tmpesrt;
 245         struct efi_system_resource_entry_v1 *v1_entries;
 246         size_t size, max, entry_size, entries_size;
 247         efi_memory_desc_t md;
 248         int rc;
 249         phys_addr_t end;
 250
 251         pr_debug("esrt-init: loading.\n");
 252         if (!esrt_table_exists())
 253                 return;
 254
 255         rc = efi_mem_desc_lookup(efi.esrt, &md);
 256         if (rc < 0) {
 257                 pr_warn("ESRT header is not in the memory map.\n");
 258                 return;
 259         }
 260
 261         max = efi_mem_desc_end(&md);
 262         if (max < efi.esrt) {
 263                 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n",
 264                        (void *)efi.esrt, (void *)max);
 265                 return;
 266         }
 267
 268         size = sizeof(*esrt);
 269         max -= efi.esrt;
 270
 271         if (max < size) {
 272                 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n",
 273                        size, max);
 274                 return;
 275         }
 276
 277         va = early_memremap(efi.esrt, size);
 278         if (!va) {
 279                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 280                        size);
 281                 return;
 282         }
 283
 284         memcpy(&tmpesrt, va, sizeof(tmpesrt));
 285
 286         if (tmpesrt.fw_resource_version == 1) {
 287                 entry_size = sizeof (*v1_entries);
 288         } else {
 289                 pr_err("Unsupported ESRT version %lld.\n",
 290                        tmpesrt.fw_resource_version);
 291                 return;
 292         }
 293
 294         if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
 295                 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
 296                        max - size, entry_size);
 297                 goto err_memunmap;
 298         }
 299
 300         /*
 301          * The format doesn't really give us any boundary to test here,
 302          * so I'm making up 128 as the max number of individually updatable
 303          * components we support.
 304          * 128 should be pretty excessive, but there's still some chance
 305          * somebody will do that someday and we'll need to raise this.
 306          */
 307         if (tmpesrt.fw_resource_count > 128) {
 308                 pr_err("ESRT says fw_resource_count has very large value %d.\n",
 309                        tmpesrt.fw_resource_count);
 310                 goto err_memunmap;
 311         }
 312
 313         /*
 314          * We know it can't be larger than N * sizeof() here, and N is limited
 315          * by the previous test to a small number, so there's no overflow.
 316          */
 317         entries_size = tmpesrt.fw_resource_count * entry_size;
 318         if (max < size + entries_size) {
 319                 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
 320                        size, max);
 321                 goto err_memunmap;
 322         }
 323
 324         /* remap it with our (plausible) new pages */
 325         early_memunmap(va, size);
 326         size += entries_size;
 327         va = early_memremap(efi.esrt, size);
 328         if (!va) {
 329                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 330                        size);
 331                 return;
 332         }
 333
 334         esrt_data = (phys_addr_t)efi.esrt;
 335         esrt_data_size = size;
 336
 337         end = esrt_data + size;
 338         pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
 339         efi_mem_reserve(esrt_data, esrt_data_size);
 340
 341         pr_debug("esrt-init: loaded.\n");
 342 err_memunmap:
 343         early_memunmap(va, size);
 344 }
 345
 346 static int __init register_entries(void)
 347 {
 348         struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
 349         int i, rc;
 350
 351         if (!esrt_table_exists())
 352                 return 0;
 353
 354         for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
 355                 void *esre = NULL;
 356                 if (esrt->fw_resource_version == 1) {
 357                         esre = &v1_entries[i];
 358                 } else {
 359                         pr_err("Unsupported ESRT version %lld.\n",
 360                                esrt->fw_resource_version);
 361                         return -EINVAL;
 362                 }
 363
 364                 rc = esre_create_sysfs_entry(esre, i);
 365                 if (rc < 0) {
 366                         pr_err("ESRT entry creation failed with error %d.\n",
 367                                rc);
 368                         return rc;
 369                 }
 370         }
 371         return 0;
 372 }
 373
 374 static void cleanup_entry_list(void)
 375 {
 376         struct esre_entry *entry, *next;
 377
 378         list_for_each_entry_safe(entry, next, &entry_list, list) {
 379                 kobject_put(&entry->kobj);
 380         }
 381 }
 382
 383 static int __init esrt_sysfs_init(void)
 384 {
 385         int error;
 386
 387         pr_debug("esrt-sysfs: loading.\n");
 388         if (!esrt_data || !esrt_data_size)
 389                 return -ENOSYS;
 390
 391         esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
 392         if (!esrt) {
 393                 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data,
 394                        esrt_data_size);
 395                 return -ENOMEM;
 396         }
 397
 398         esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
 399         if (!esrt_kobj) {
 400                 pr_err("Firmware table registration failed.\n");
 401                 error = -ENOMEM;
 402                 goto err;
 403         }
 404
 405         error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
 406         if (error) {
 407                 pr_err("Sysfs attribute export failed with error %d.\n",
 408                        error);
 409                 goto err_remove_esrt;
 410         }
 411
 412         esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
 413         if (!esrt_kset) {
 414                 pr_err("kset creation failed.\n");
 415                 error = -ENOMEM;
 416                 goto err_remove_group;
 417         }
 418
 419         error = register_entries();
 420         if (error)
 421                 goto err_cleanup_list;
 422
 423         pr_debug("esrt-sysfs: loaded.\n");
 424
 425         return 0;
 426 err_cleanup_list:
 427         cleanup_entry_list();
 428         kset_unregister(esrt_kset);
 429 err_remove_group:
 430         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 431 err_remove_esrt:
 432         kobject_put(esrt_kobj);
 433 err:
 434         kfree(esrt);
 435         esrt = NULL;
 436         return error;
 437 }
 438 device_initcall(esrt_sysfs_init);
 439
 440 /*
 441 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
 442 MODULE_DESCRIPTION("EFI System Resource Table support");
 443 MODULE_LICENSE("GPL");
 444 */