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 const 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 */ 445