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