1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * esrt.c 4 * 5 * This module exports EFI System Resource Table (ESRT) entries into userspace 6 * through the sysfs file system. The ESRT provides a read-only catalog of 7 * system components for which the system accepts firmware upgrades via UEFI's 8 * "Capsule Update" feature. This module allows userland utilities to evaluate 9 * what firmware updates can be applied to this system, and potentially arrange 10 * for those updates to occur. 11 * 12 * Data is currently found below /sys/firmware/efi/esrt/... 13 */ 14 #define pr_fmt(fmt) "esrt: " fmt 15 16 #include <linux/capability.h> 17 #include <linux/device.h> 18 #include <linux/efi.h> 19 #include <linux/init.h> 20 #include <linux/io.h> 21 #include <linux/kernel.h> 22 #include <linux/kobject.h> 23 #include <linux/list.h> 24 #include <linux/memblock.h> 25 #include <linux/slab.h> 26 #include <linux/types.h> 27 28 #include <asm/io.h> 29 #include <asm/early_ioremap.h> 30 31 struct efi_system_resource_entry_v1 { 32 efi_guid_t fw_class; 33 u32 fw_type; 34 u32 fw_version; 35 u32 lowest_supported_fw_version; 36 u32 capsule_flags; 37 u32 last_attempt_version; 38 u32 last_attempt_status; 39 }; 40 41 /* 42 * _count and _version are what they seem like. _max is actually just 43 * accounting info for the firmware when creating the table; it should never 44 * have been exposed to us. To wit, the spec says: 45 * The maximum number of resource array entries that can be within the 46 * table without reallocating the table, must not be zero. 47 * Since there's no guidance about what that means in terms of memory layout, 48 * it means nothing to us. 49 */ 50 struct efi_system_resource_table { 51 u32 fw_resource_count; 52 u32 fw_resource_count_max; 53 u64 fw_resource_version; 54 u8 entries[]; 55 }; 56 57 static phys_addr_t esrt_data; 58 static size_t esrt_data_size; 59 60 static struct efi_system_resource_table *esrt; 61 62 struct esre_entry { 63 union { 64 struct efi_system_resource_entry_v1 *esre1; 65 } esre; 66 67 struct kobject kobj; 68 struct list_head list; 69 }; 70 71 /* global list of esre_entry. */ 72 static LIST_HEAD(entry_list); 73 74 /* entry attribute */ 75 struct esre_attribute { 76 struct attribute attr; 77 ssize_t (*show)(struct esre_entry *entry, char *buf); 78 ssize_t (*store)(struct esre_entry *entry, 79 const char *buf, size_t count); 80 }; 81 82 static struct esre_entry *to_entry(struct kobject *kobj) 83 { 84 return container_of(kobj, struct esre_entry, kobj); 85 } 86 87 static struct esre_attribute *to_attr(struct attribute *attr) 88 { 89 return container_of(attr, struct esre_attribute, attr); 90 } 91 92 static ssize_t esre_attr_show(struct kobject *kobj, 93 struct attribute *_attr, char *buf) 94 { 95 struct esre_entry *entry = to_entry(kobj); 96 struct esre_attribute *attr = to_attr(_attr); 97 98 /* Don't tell normal users what firmware versions we've got... */ 99 if (!capable(CAP_SYS_ADMIN)) 100 return -EACCES; 101 102 return attr->show(entry, buf); 103 } 104 105 static const struct sysfs_ops esre_attr_ops = { 106 .show = esre_attr_show, 107 }; 108 109 /* Generic ESRT Entry ("ESRE") support. */ 110 static ssize_t fw_class_show(struct esre_entry *entry, char *buf) 111 { 112 char *str = buf; 113 114 efi_guid_to_str(&entry->esre.esre1->fw_class, str); 115 str += strlen(str); 116 str += sprintf(str, "\n"); 117 118 return str - buf; 119 } 120 121 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400); 122 123 #define esre_attr_decl(name, size, fmt) \ 124 static ssize_t 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_RO_MODE(name, 0400) 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 kobject_put(&entry->kobj); 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 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_RO_MODE(name, 0400) 202 203 esrt_attr_decl(fw_resource_count, 32, "%u"); 204 esrt_attr_decl(fw_resource_count_max, 32, "%u"); 205 esrt_attr_decl(fw_resource_version, 64, "%llu"); 206 207 static struct attribute *esrt_attrs[] = { 208 &esrt_fw_resource_count.attr, 209 &esrt_fw_resource_count_max.attr, 210 &esrt_fw_resource_version.attr, 211 NULL, 212 }; 213 214 static inline int esrt_table_exists(void) 215 { 216 if (!efi_enabled(EFI_CONFIG_TABLES)) 217 return 0; 218 if (efi.esrt == EFI_INVALID_TABLE_ADDR) 219 return 0; 220 return 1; 221 } 222 223 static umode_t esrt_attr_is_visible(struct kobject *kobj, 224 struct attribute *attr, int n) 225 { 226 if (!esrt_table_exists()) 227 return 0; 228 return attr->mode; 229 } 230 231 static const struct attribute_group esrt_attr_group = { 232 .attrs = esrt_attrs, 233 .is_visible = esrt_attr_is_visible, 234 }; 235 236 /* 237 * remap the table, validate it, mark it reserved and unmap it. 238 */ 239 void __init efi_esrt_init(void) 240 { 241 void *va; 242 struct efi_system_resource_table tmpesrt; 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 if (!efi_enabled(EFI_MEMMAP)) 249 return; 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 (!(md.attribute & EFI_MEMORY_RUNTIME) && 258 md.type != EFI_BOOT_SERVICES_DATA && 259 md.type != EFI_RUNTIME_SERVICES_DATA)) { 260 pr_warn("ESRT header is not in the memory map.\n"); 261 return; 262 } 263 264 max = efi_mem_desc_end(&md); 265 if (max < efi.esrt) { 266 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n", 267 (void *)efi.esrt, (void *)max); 268 return; 269 } 270 271 size = sizeof(*esrt); 272 max -= efi.esrt; 273 274 if (max < size) { 275 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n", 276 size, max); 277 return; 278 } 279 280 va = early_memremap(efi.esrt, size); 281 if (!va) { 282 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 283 size); 284 return; 285 } 286 287 memcpy(&tmpesrt, va, sizeof(tmpesrt)); 288 early_memunmap(va, size); 289 290 if (tmpesrt.fw_resource_version != 1) { 291 pr_err("Unsupported ESRT version %lld.\n", 292 tmpesrt.fw_resource_version); 293 return; 294 } 295 296 entry_size = sizeof(struct efi_system_resource_entry_v1); 297 if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) { 298 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n", 299 max - size, entry_size); 300 return; 301 } 302 303 /* 304 * The format doesn't really give us any boundary to test here, 305 * so I'm making up 128 as the max number of individually updatable 306 * components we support. 307 * 128 should be pretty excessive, but there's still some chance 308 * somebody will do that someday and we'll need to raise this. 309 */ 310 if (tmpesrt.fw_resource_count > 128) { 311 pr_err("ESRT says fw_resource_count has very large value %d.\n", 312 tmpesrt.fw_resource_count); 313 return; 314 } 315 316 /* 317 * We know it can't be larger than N * sizeof() here, and N is limited 318 * by the previous test to a small number, so there's no overflow. 319 */ 320 entries_size = tmpesrt.fw_resource_count * entry_size; 321 if (max < size + entries_size) { 322 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n", 323 size, max); 324 return; 325 } 326 327 size += entries_size; 328 329 esrt_data = (phys_addr_t)efi.esrt; 330 esrt_data_size = size; 331 332 end = esrt_data + size; 333 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end); 334 if (md.type == EFI_BOOT_SERVICES_DATA) 335 efi_mem_reserve(esrt_data, esrt_data_size); 336 337 pr_debug("esrt-init: loaded.\n"); 338 } 339 340 static int __init register_entries(void) 341 { 342 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries; 343 int i, rc; 344 345 if (!esrt_table_exists()) 346 return 0; 347 348 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) { 349 void *esre = NULL; 350 if (esrt->fw_resource_version == 1) { 351 esre = &v1_entries[i]; 352 } else { 353 pr_err("Unsupported ESRT version %lld.\n", 354 esrt->fw_resource_version); 355 return -EINVAL; 356 } 357 358 rc = esre_create_sysfs_entry(esre, i); 359 if (rc < 0) { 360 pr_err("ESRT entry creation failed with error %d.\n", 361 rc); 362 return rc; 363 } 364 } 365 return 0; 366 } 367 368 static void cleanup_entry_list(void) 369 { 370 struct esre_entry *entry, *next; 371 372 list_for_each_entry_safe(entry, next, &entry_list, list) { 373 kobject_put(&entry->kobj); 374 } 375 } 376 377 static int __init esrt_sysfs_init(void) 378 { 379 int error; 380 381 pr_debug("esrt-sysfs: loading.\n"); 382 if (!esrt_data || !esrt_data_size) 383 return -ENOSYS; 384 385 esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB); 386 if (!esrt) { 387 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data, 388 esrt_data_size); 389 return -ENOMEM; 390 } 391 392 esrt_kobj = kobject_create_and_add("esrt", efi_kobj); 393 if (!esrt_kobj) { 394 pr_err("Firmware table registration failed.\n"); 395 error = -ENOMEM; 396 goto err; 397 } 398 399 error = sysfs_create_group(esrt_kobj, &esrt_attr_group); 400 if (error) { 401 pr_err("Sysfs attribute export failed with error %d.\n", 402 error); 403 goto err_remove_esrt; 404 } 405 406 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj); 407 if (!esrt_kset) { 408 pr_err("kset creation failed.\n"); 409 error = -ENOMEM; 410 goto err_remove_group; 411 } 412 413 error = register_entries(); 414 if (error) 415 goto err_cleanup_list; 416 417 pr_debug("esrt-sysfs: loaded.\n"); 418 419 return 0; 420 err_cleanup_list: 421 cleanup_entry_list(); 422 kset_unregister(esrt_kset); 423 err_remove_group: 424 sysfs_remove_group(esrt_kobj, &esrt_attr_group); 425 err_remove_esrt: 426 kobject_put(esrt_kobj); 427 err: 428 memunmap(esrt); 429 esrt = NULL; 430 return error; 431 } 432 device_initcall(esrt_sysfs_init); 433 434 /* 435 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>"); 436 MODULE_DESCRIPTION("EFI System Resource Table support"); 437 MODULE_LICENSE("GPL"); 438 */ 439