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; 170 171 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 172 if (!entry) 173 return -ENOMEM; 174 175 entry->kobj.kset = esrt_kset; 176 177 if (esrt->fw_resource_version == 1) { 178 int rc = 0; 179 180 entry->esre.esre1 = esre; 181 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL, 182 "entry%d", entry_num); 183 if (rc) { 184 kfree(entry); 185 return rc; 186 } 187 } 188 189 list_add_tail(&entry->list, &entry_list); 190 return 0; 191 } 192 193 /* support for displaying ESRT fields at the top level */ 194 #define esrt_attr_decl(name, size, fmt) \ 195 static ssize_t esrt_##name##_show(struct kobject *kobj, \ 196 struct kobj_attribute *attr, char *buf)\ 197 { \ 198 return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \ 199 } \ 200 \ 201 static struct kobj_attribute esrt_##name = __ATTR(name, 0400, \ 202 esrt_##name##_show, NULL) 203 204 esrt_attr_decl(fw_resource_count, 32, "%u"); 205 esrt_attr_decl(fw_resource_count_max, 32, "%u"); 206 esrt_attr_decl(fw_resource_version, 64, "%llu"); 207 208 static struct attribute *esrt_attrs[] = { 209 &esrt_fw_resource_count.attr, 210 &esrt_fw_resource_count_max.attr, 211 &esrt_fw_resource_version.attr, 212 NULL, 213 }; 214 215 static inline int esrt_table_exists(void) 216 { 217 if (!efi_enabled(EFI_CONFIG_TABLES)) 218 return 0; 219 if (efi.esrt == EFI_INVALID_TABLE_ADDR) 220 return 0; 221 return 1; 222 } 223 224 static umode_t esrt_attr_is_visible(struct kobject *kobj, 225 struct attribute *attr, int n) 226 { 227 if (!esrt_table_exists()) 228 return 0; 229 return attr->mode; 230 } 231 232 static struct attribute_group esrt_attr_group = { 233 .attrs = esrt_attrs, 234 .is_visible = esrt_attr_is_visible, 235 }; 236 237 /* 238 * remap the table, copy it to kmalloced pages, and unmap it. 239 */ 240 void __init efi_esrt_init(void) 241 { 242 void *va; 243 struct efi_system_resource_table tmpesrt; 244 struct efi_system_resource_entry_v1 *v1_entries; 245 size_t size, max, entry_size, entries_size; 246 efi_memory_desc_t md; 247 int rc; 248 phys_addr_t end; 249 250 pr_debug("esrt-init: loading.\n"); 251 if (!esrt_table_exists()) 252 return; 253 254 rc = efi_mem_desc_lookup(efi.esrt, &md); 255 if (rc < 0) { 256 pr_err("ESRT header is not in the memory map.\n"); 257 return; 258 } 259 260 max = efi_mem_desc_end(&md); 261 if (max < efi.esrt) { 262 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n", 263 (void *)efi.esrt, (void *)max); 264 return; 265 } 266 267 size = sizeof(*esrt); 268 max -= efi.esrt; 269 270 if (max < size) { 271 pr_err("ESRT header doen't fit on single memory map entry. (size: %zu max: %zu)\n", 272 size, max); 273 return; 274 } 275 276 va = early_memremap(efi.esrt, size); 277 if (!va) { 278 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 279 size); 280 return; 281 } 282 283 memcpy(&tmpesrt, va, sizeof(tmpesrt)); 284 285 if (tmpesrt.fw_resource_version == 1) { 286 entry_size = sizeof (*v1_entries); 287 } else { 288 pr_err("Unsupported ESRT version %lld.\n", 289 tmpesrt.fw_resource_version); 290 return; 291 } 292 293 if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) { 294 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n", 295 max - size, entry_size); 296 goto err_memunmap; 297 } 298 299 /* 300 * The format doesn't really give us any boundary to test here, 301 * so I'm making up 128 as the max number of individually updatable 302 * components we support. 303 * 128 should be pretty excessive, but there's still some chance 304 * somebody will do that someday and we'll need to raise this. 305 */ 306 if (tmpesrt.fw_resource_count > 128) { 307 pr_err("ESRT says fw_resource_count has very large value %d.\n", 308 tmpesrt.fw_resource_count); 309 goto err_memunmap; 310 } 311 312 /* 313 * We know it can't be larger than N * sizeof() here, and N is limited 314 * by the previous test to a small number, so there's no overflow. 315 */ 316 entries_size = tmpesrt.fw_resource_count * entry_size; 317 if (max < size + entries_size) { 318 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n", 319 size, max); 320 goto err_memunmap; 321 } 322 323 /* remap it with our (plausible) new pages */ 324 early_memunmap(va, size); 325 size += entries_size; 326 va = early_memremap(efi.esrt, size); 327 if (!va) { 328 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 329 size); 330 return; 331 } 332 333 esrt_data = (phys_addr_t)efi.esrt; 334 esrt_data_size = size; 335 336 end = esrt_data + size; 337 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end); 338 memblock_reserve(esrt_data, esrt_data_size); 339 340 pr_debug("esrt-init: loaded.\n"); 341 err_memunmap: 342 early_memunmap(va, size); 343 } 344 345 static int __init register_entries(void) 346 { 347 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries; 348 int i, rc; 349 350 if (!esrt_table_exists()) 351 return 0; 352 353 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) { 354 void *esre = NULL; 355 if (esrt->fw_resource_version == 1) { 356 esre = &v1_entries[i]; 357 } else { 358 pr_err("Unsupported ESRT version %lld.\n", 359 esrt->fw_resource_version); 360 return -EINVAL; 361 } 362 363 rc = esre_create_sysfs_entry(esre, i); 364 if (rc < 0) { 365 pr_err("ESRT entry creation failed with error %d.\n", 366 rc); 367 return rc; 368 } 369 } 370 return 0; 371 } 372 373 static void cleanup_entry_list(void) 374 { 375 struct esre_entry *entry, *next; 376 377 list_for_each_entry_safe(entry, next, &entry_list, list) { 378 kobject_put(&entry->kobj); 379 } 380 } 381 382 static int __init esrt_sysfs_init(void) 383 { 384 int error; 385 struct efi_system_resource_table __iomem *ioesrt; 386 387 pr_debug("esrt-sysfs: loading.\n"); 388 if (!esrt_data || !esrt_data_size) 389 return -ENOSYS; 390 391 ioesrt = ioremap(esrt_data, esrt_data_size); 392 if (!ioesrt) { 393 pr_err("ioremap(%pa, %zu) failed.\n", &esrt_data, 394 esrt_data_size); 395 return -ENOMEM; 396 } 397 398 esrt = kmalloc(esrt_data_size, GFP_KERNEL); 399 if (!esrt) { 400 pr_err("kmalloc failed. (wanted %zu bytes)\n", esrt_data_size); 401 iounmap(ioesrt); 402 return -ENOMEM; 403 } 404 405 memcpy_fromio(esrt, ioesrt, esrt_data_size); 406 407 esrt_kobj = kobject_create_and_add("esrt", efi_kobj); 408 if (!esrt_kobj) { 409 pr_err("Firmware table registration failed.\n"); 410 error = -ENOMEM; 411 goto err; 412 } 413 414 error = sysfs_create_group(esrt_kobj, &esrt_attr_group); 415 if (error) { 416 pr_err("Sysfs attribute export failed with error %d.\n", 417 error); 418 goto err_remove_esrt; 419 } 420 421 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj); 422 if (!esrt_kset) { 423 pr_err("kset creation failed.\n"); 424 error = -ENOMEM; 425 goto err_remove_group; 426 } 427 428 error = register_entries(); 429 if (error) 430 goto err_cleanup_list; 431 432 memblock_remove(esrt_data, esrt_data_size); 433 434 pr_debug("esrt-sysfs: loaded.\n"); 435 436 return 0; 437 err_cleanup_list: 438 cleanup_entry_list(); 439 kset_unregister(esrt_kset); 440 err_remove_group: 441 sysfs_remove_group(esrt_kobj, &esrt_attr_group); 442 err_remove_esrt: 443 kobject_put(esrt_kobj); 444 err: 445 kfree(esrt); 446 esrt = NULL; 447 return error; 448 } 449 device_initcall(esrt_sysfs_init); 450 451 /* 452 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>"); 453 MODULE_DESCRIPTION("EFI System Resource Table support"); 454 MODULE_LICENSE("GPL"); 455 */ 456