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/module.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         int rc = 0;
 171         struct esre_entry *entry;
 172         char name[20];
 173
 174         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 175         if (!entry)
 176                 return -ENOMEM;
 177
 178         sprintf(name, "entry%d", entry_num);
 179
 180         entry->kobj.kset = esrt_kset;
 181
 182         if (esrt->fw_resource_version == 1) {
 183                 entry->esre.esre1 = esre;
 184                 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
 185                                           "%s", name);
 186         }
 187         if (rc) {
 188                 kfree(entry);
 189                 return rc;
 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
 252         pr_debug("esrt-init: loading.\n");
 253         if (!esrt_table_exists())
 254                 return;
 255
 256         rc = efi_mem_desc_lookup(efi.esrt, &md);
 257         if (rc < 0) {
 258                 pr_err("ESRT header is not in the memory map.\n");
 259                 return;
 260         }
 261
 262         max = efi_mem_desc_end(&md);
 263         if (max < efi.esrt) {
 264                 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n",
 265                        (void *)efi.esrt, (void *)max);
 266                 return;
 267         }
 268
 269         size = sizeof(*esrt);
 270         max -= efi.esrt;
 271
 272         if (max < size) {
 273                 pr_err("ESRT header doen't fit on single memory map entry. (size: %zu max: %zu)\n",
 274                        size, max);
 275                 return;
 276         }
 277
 278         va = early_memremap(efi.esrt, size);
 279         if (!va) {
 280                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 281                        size);
 282                 return;
 283         }
 284
 285         memcpy(&tmpesrt, va, sizeof(tmpesrt));
 286
 287         if (tmpesrt.fw_resource_version == 1) {
 288                 entry_size = sizeof (*v1_entries);
 289         } else {
 290                 pr_err("Unsupported ESRT version %lld.\n",
 291                        tmpesrt.fw_resource_version);
 292                 return;
 293         }
 294
 295         if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
 296                 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
 297                        max - size, entry_size);
 298                 goto err_memunmap;
 299         }
 300
 301         /*
 302          * The format doesn't really give us any boundary to test here,
 303          * so I'm making up 128 as the max number of individually updatable
 304          * components we support.
 305          * 128 should be pretty excessive, but there's still some chance
 306          * somebody will do that someday and we'll need to raise this.
 307          */
 308         if (tmpesrt.fw_resource_count > 128) {
 309                 pr_err("ESRT says fw_resource_count has very large value %d.\n",
 310                        tmpesrt.fw_resource_count);
 311                 goto err_memunmap;
 312         }
 313
 314         /*
 315          * We know it can't be larger than N * sizeof() here, and N is limited
 316          * by the previous test to a small number, so there's no overflow.
 317          */
 318         entries_size = tmpesrt.fw_resource_count * entry_size;
 319         if (max < size + entries_size) {
 320                 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
 321                        size, max);
 322                 goto err_memunmap;
 323         }
 324
 325         /* remap it with our (plausible) new pages */
 326         early_memunmap(va, size);
 327         size += entries_size;
 328         va = early_memremap(efi.esrt, size);
 329         if (!va) {
 330                 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
 331                        size);
 332                 return;
 333         }
 334
 335         esrt_data = (phys_addr_t)efi.esrt;
 336         esrt_data_size = size;
 337
 338         pr_info("Reserving ESRT space from %p to %p.\n", (void *)esrt_data,
 339                 (char *)esrt_data + size);
 340         memblock_reserve(esrt_data, esrt_data_size);
 341
 342         pr_debug("esrt-init: loaded.\n");
 343 err_memunmap:
 344         early_memunmap(va, size);
 345 }
 346
 347 static int __init register_entries(void)
 348 {
 349         struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
 350         int i, rc;
 351
 352         if (!esrt_table_exists())
 353                 return 0;
 354
 355         for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
 356                 void *entry;
 357                 if (esrt->fw_resource_version == 1) {
 358                         entry = &v1_entries[i];
 359                 }
 360                 rc = esre_create_sysfs_entry(entry, i);
 361                 if (rc < 0) {
 362                         pr_err("ESRT entry creation failed with error %d.\n",
 363                                rc);
 364                         return rc;
 365                 }
 366         }
 367         return 0;
 368 }
 369
 370 static void cleanup_entry_list(void)
 371 {
 372         struct esre_entry *entry, *next;
 373
 374         list_for_each_entry_safe(entry, next, &entry_list, list) {
 375                 kobject_put(&entry->kobj);
 376         }
 377 }
 378
 379 static int __init esrt_sysfs_init(void)
 380 {
 381         int error;
 382         struct efi_system_resource_table __iomem *ioesrt;
 383
 384         pr_debug("esrt-sysfs: loading.\n");
 385         if (!esrt_data || !esrt_data_size)
 386                 return -ENOSYS;
 387
 388         ioesrt = ioremap(esrt_data, esrt_data_size);
 389         if (!ioesrt) {
 390                 pr_err("ioremap(%p, %zu) failed.\n", (void *)esrt_data,
 391                        esrt_data_size);
 392                 return -ENOMEM;
 393         }
 394
 395         esrt = kmalloc(esrt_data_size, GFP_KERNEL);
 396         if (!esrt) {
 397                 pr_err("kmalloc failed. (wanted %zu bytes)\n", esrt_data_size);
 398                 iounmap(ioesrt);
 399                 return -ENOMEM;
 400         }
 401
 402         memcpy_fromio(esrt, ioesrt, esrt_data_size);
 403
 404         esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
 405         if (!esrt_kobj) {
 406                 pr_err("Firmware table registration failed.\n");
 407                 error = -ENOMEM;
 408                 goto err;
 409         }
 410
 411         error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
 412         if (error) {
 413                 pr_err("Sysfs attribute export failed with error %d.\n",
 414                        error);
 415                 goto err_remove_esrt;
 416         }
 417
 418         esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
 419         if (!esrt_kset) {
 420                 pr_err("kset creation failed.\n");
 421                 error = -ENOMEM;
 422                 goto err_remove_group;
 423         }
 424
 425         error = register_entries();
 426         if (error)
 427                 goto err_cleanup_list;
 428
 429         memblock_remove(esrt_data, esrt_data_size);
 430
 431         pr_debug("esrt-sysfs: loaded.\n");
 432
 433         return 0;
 434 err_cleanup_list:
 435         cleanup_entry_list();
 436         kset_unregister(esrt_kset);
 437 err_remove_group:
 438         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 439 err_remove_esrt:
 440         kobject_put(esrt_kobj);
 441 err:
 442         kfree(esrt);
 443         esrt = NULL;
 444         return error;
 445 }
 446
 447 static void __exit esrt_sysfs_exit(void)
 448 {
 449         pr_debug("esrt-sysfs: unloading.\n");
 450         cleanup_entry_list();
 451         kset_unregister(esrt_kset);
 452         sysfs_remove_group(esrt_kobj, &esrt_attr_group);
 453         kfree(esrt);
 454         esrt = NULL;
 455         kobject_del(esrt_kobj);
 456         kobject_put(esrt_kobj);
 457 }
 458
 459 module_init(esrt_sysfs_init);
 460 module_exit(esrt_sysfs_exit);
 461
 462 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
 463 MODULE_DESCRIPTION("EFI System Resource Table support");
 464 MODULE_LICENSE("GPL");