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/slab.h> 24 #include <linux/types.h> 25 26 #include <asm/io.h> 27 #include <asm/early_ioremap.h> 28 29 struct efi_system_resource_entry_v1 { 30 efi_guid_t fw_class; 31 u32 fw_type; 32 u32 fw_version; 33 u32 lowest_supported_fw_version; 34 u32 capsule_flags; 35 u32 last_attempt_version; 36 u32 last_attempt_status; 37 }; 38 39 /* 40 * _count and _version are what they seem like. _max is actually just 41 * accounting info for the firmware when creating the table; it should never 42 * have been exposed to us. To wit, the spec says: 43 * The maximum number of resource array entries that can be within the 44 * table without reallocating the table, must not be zero. 45 * Since there's no guidance about what that means in terms of memory layout, 46 * it means nothing to us. 47 */ 48 struct efi_system_resource_table { 49 u32 fw_resource_count; 50 u32 fw_resource_count_max; 51 u64 fw_resource_version; 52 u8 entries[]; 53 }; 54 55 static phys_addr_t esrt_data; 56 static size_t esrt_data_size; 57 58 static struct efi_system_resource_table *esrt; 59 60 struct esre_entry { 61 union { 62 struct efi_system_resource_entry_v1 *esre1; 63 } esre; 64 65 struct kobject kobj; 66 struct list_head list; 67 }; 68 69 /* global list of esre_entry. */ 70 static LIST_HEAD(entry_list); 71 72 /* entry attribute */ 73 struct esre_attribute { 74 struct attribute attr; 75 ssize_t (*show)(struct esre_entry *entry, char *buf); 76 ssize_t (*store)(struct esre_entry *entry, 77 const char *buf, size_t count); 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 /* Don't tell normal users what firmware versions we've got... */ 97 if (!capable(CAP_SYS_ADMIN)) 98 return -EACCES; 99 100 return attr->show(entry, buf); 101 } 102 103 static const struct sysfs_ops esre_attr_ops = { 104 .show = esre_attr_show, 105 }; 106 107 /* Generic ESRT Entry ("ESRE") support. */ 108 static ssize_t esre_fw_class_show(struct esre_entry *entry, char *buf) 109 { 110 char *str = buf; 111 112 efi_guid_to_str(&entry->esre.esre1->fw_class, str); 113 str += strlen(str); 114 str += sprintf(str, "\n"); 115 116 return str - buf; 117 } 118 119 static struct esre_attribute esre_fw_class = __ATTR(fw_class, 0400, 120 esre_fw_class_show, NULL); 121 122 #define esre_attr_decl(name, size, fmt) \ 123 static ssize_t esre_##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(name, 0400, \ 130 esre_##name##_show, NULL) 131 132 esre_attr_decl(fw_type, 32, "%u"); 133 esre_attr_decl(fw_version, 32, "%u"); 134 esre_attr_decl(lowest_supported_fw_version, 32, "%u"); 135 esre_attr_decl(capsule_flags, 32, "0x%x"); 136 esre_attr_decl(last_attempt_version, 32, "%u"); 137 esre_attr_decl(last_attempt_status, 32, "%u"); 138 139 static struct attribute *esre1_attrs[] = { 140 &esre_fw_class.attr, 141 &esre_fw_type.attr, 142 &esre_fw_version.attr, 143 &esre_lowest_supported_fw_version.attr, 144 &esre_capsule_flags.attr, 145 &esre_last_attempt_version.attr, 146 &esre_last_attempt_status.attr, 147 NULL 148 }; 149 static void esre_release(struct kobject *kobj) 150 { 151 struct esre_entry *entry = to_entry(kobj); 152 153 list_del(&entry->list); 154 kfree(entry); 155 } 156 157 static struct kobj_type esre1_ktype = { 158 .release = esre_release, 159 .sysfs_ops = &esre_attr_ops, 160 .default_attrs = esre1_attrs, 161 }; 162 163 164 static struct kobject *esrt_kobj; 165 static struct kset *esrt_kset; 166 167 static int esre_create_sysfs_entry(void *esre, int entry_num) 168 { 169 struct esre_entry *entry; 170 char name[20]; 171 172 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 173 if (!entry) 174 return -ENOMEM; 175 176 sprintf(name, "entry%d", entry_num); 177 178 entry->kobj.kset = esrt_kset; 179 180 if (esrt->fw_resource_version == 1) { 181 int rc = 0; 182 183 entry->esre.esre1 = esre; 184 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL, 185 "%s", name); 186 if (rc) { 187 kfree(entry); 188 return rc; 189 } 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 phys_addr_t end; 252 253 pr_debug("esrt-init: loading.\n"); 254 if (!esrt_table_exists()) 255 return; 256 257 rc = efi_mem_desc_lookup(efi.esrt, &md); 258 if (rc < 0) { 259 pr_err("ESRT header is not in the memory map.\n"); 260 return; 261 } 262 263 max = efi_mem_desc_end(&md); 264 if (max < efi.esrt) { 265 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n", 266 (void *)efi.esrt, (void *)max); 267 return; 268 } 269 270 size = sizeof(*esrt); 271 max -= efi.esrt; 272 273 if (max < size) { 274 pr_err("ESRT header doen't fit on single memory map entry. (size: %zu max: %zu)\n", 275 size, max); 276 return; 277 } 278 279 va = early_memremap(efi.esrt, size); 280 if (!va) { 281 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 282 size); 283 return; 284 } 285 286 memcpy(&tmpesrt, va, sizeof(tmpesrt)); 287 288 if (tmpesrt.fw_resource_version == 1) { 289 entry_size = sizeof (*v1_entries); 290 } else { 291 pr_err("Unsupported ESRT version %lld.\n", 292 tmpesrt.fw_resource_version); 293 return; 294 } 295 296 if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) { 297 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n", 298 max - size, entry_size); 299 goto err_memunmap; 300 } 301 302 /* 303 * The format doesn't really give us any boundary to test here, 304 * so I'm making up 128 as the max number of individually updatable 305 * components we support. 306 * 128 should be pretty excessive, but there's still some chance 307 * somebody will do that someday and we'll need to raise this. 308 */ 309 if (tmpesrt.fw_resource_count > 128) { 310 pr_err("ESRT says fw_resource_count has very large value %d.\n", 311 tmpesrt.fw_resource_count); 312 goto err_memunmap; 313 } 314 315 /* 316 * We know it can't be larger than N * sizeof() here, and N is limited 317 * by the previous test to a small number, so there's no overflow. 318 */ 319 entries_size = tmpesrt.fw_resource_count * entry_size; 320 if (max < size + entries_size) { 321 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n", 322 size, max); 323 goto err_memunmap; 324 } 325 326 /* remap it with our (plausible) new pages */ 327 early_memunmap(va, size); 328 size += entries_size; 329 va = early_memremap(efi.esrt, size); 330 if (!va) { 331 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 332 size); 333 return; 334 } 335 336 esrt_data = (phys_addr_t)efi.esrt; 337 esrt_data_size = size; 338 339 end = esrt_data + size; 340 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end); 341 memblock_reserve(esrt_data, esrt_data_size); 342 343 pr_debug("esrt-init: loaded.\n"); 344 err_memunmap: 345 early_memunmap(va, size); 346 } 347 348 static int __init register_entries(void) 349 { 350 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries; 351 int i, rc; 352 353 if (!esrt_table_exists()) 354 return 0; 355 356 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) { 357 void *esre = NULL; 358 if (esrt->fw_resource_version == 1) { 359 esre = &v1_entries[i]; 360 } else { 361 pr_err("Unsupported ESRT version %lld.\n", 362 esrt->fw_resource_version); 363 return -EINVAL; 364 } 365 366 rc = esre_create_sysfs_entry(esre, i); 367 if (rc < 0) { 368 pr_err("ESRT entry creation failed with error %d.\n", 369 rc); 370 return rc; 371 } 372 } 373 return 0; 374 } 375 376 static void cleanup_entry_list(void) 377 { 378 struct esre_entry *entry, *next; 379 380 list_for_each_entry_safe(entry, next, &entry_list, list) { 381 kobject_put(&entry->kobj); 382 } 383 } 384 385 static int __init esrt_sysfs_init(void) 386 { 387 int error; 388 struct efi_system_resource_table __iomem *ioesrt; 389 390 pr_debug("esrt-sysfs: loading.\n"); 391 if (!esrt_data || !esrt_data_size) 392 return -ENOSYS; 393 394 ioesrt = ioremap(esrt_data, esrt_data_size); 395 if (!ioesrt) { 396 pr_err("ioremap(%pa, %zu) failed.\n", &esrt_data, 397 esrt_data_size); 398 return -ENOMEM; 399 } 400 401 esrt = kmalloc(esrt_data_size, GFP_KERNEL); 402 if (!esrt) { 403 pr_err("kmalloc failed. (wanted %zu bytes)\n", esrt_data_size); 404 iounmap(ioesrt); 405 return -ENOMEM; 406 } 407 408 memcpy_fromio(esrt, ioesrt, esrt_data_size); 409 410 esrt_kobj = kobject_create_and_add("esrt", efi_kobj); 411 if (!esrt_kobj) { 412 pr_err("Firmware table registration failed.\n"); 413 error = -ENOMEM; 414 goto err; 415 } 416 417 error = sysfs_create_group(esrt_kobj, &esrt_attr_group); 418 if (error) { 419 pr_err("Sysfs attribute export failed with error %d.\n", 420 error); 421 goto err_remove_esrt; 422 } 423 424 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj); 425 if (!esrt_kset) { 426 pr_err("kset creation failed.\n"); 427 error = -ENOMEM; 428 goto err_remove_group; 429 } 430 431 error = register_entries(); 432 if (error) 433 goto err_cleanup_list; 434 435 memblock_remove(esrt_data, esrt_data_size); 436 437 pr_debug("esrt-sysfs: loaded.\n"); 438 439 return 0; 440 err_cleanup_list: 441 cleanup_entry_list(); 442 kset_unregister(esrt_kset); 443 err_remove_group: 444 sysfs_remove_group(esrt_kobj, &esrt_attr_group); 445 err_remove_esrt: 446 kobject_put(esrt_kobj); 447 err: 448 kfree(esrt); 449 esrt = NULL; 450 return error; 451 } 452 device_initcall(esrt_sysfs_init); 453 454 /* 455 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>"); 456 MODULE_DESCRIPTION("EFI System Resource Table support"); 457 MODULE_LICENSE("GPL"); 458 */ 459