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 }; 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 return attr->show(entry, buf); 97 } 98 99 static const struct sysfs_ops esre_attr_ops = { 100 .show = esre_attr_show, 101 }; 102 103 /* Generic ESRT Entry ("ESRE") support. */ 104 static ssize_t fw_class_show(struct esre_entry *entry, char *buf) 105 { 106 char *str = buf; 107 108 efi_guid_to_str(&entry->esre.esre1->fw_class, str); 109 str += strlen(str); 110 str += sprintf(str, "\n"); 111 112 return str - buf; 113 } 114 115 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400); 116 117 #define esre_attr_decl(name, size, fmt) \ 118 static ssize_t name##_show(struct esre_entry *entry, char *buf) \ 119 { \ 120 return sprintf(buf, fmt "\n", \ 121 le##size##_to_cpu(entry->esre.esre1->name)); \ 122 } \ 123 \ 124 static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400) 125 126 esre_attr_decl(fw_type, 32, "%u"); 127 esre_attr_decl(fw_version, 32, "%u"); 128 esre_attr_decl(lowest_supported_fw_version, 32, "%u"); 129 esre_attr_decl(capsule_flags, 32, "0x%x"); 130 esre_attr_decl(last_attempt_version, 32, "%u"); 131 esre_attr_decl(last_attempt_status, 32, "%u"); 132 133 static struct attribute *esre1_attrs[] = { 134 &esre_fw_class.attr, 135 &esre_fw_type.attr, 136 &esre_fw_version.attr, 137 &esre_lowest_supported_fw_version.attr, 138 &esre_capsule_flags.attr, 139 &esre_last_attempt_version.attr, 140 &esre_last_attempt_status.attr, 141 NULL 142 }; 143 ATTRIBUTE_GROUPS(esre1); 144 145 static void esre_release(struct kobject *kobj) 146 { 147 struct esre_entry *entry = to_entry(kobj); 148 149 list_del(&entry->list); 150 kfree(entry); 151 } 152 153 static const struct kobj_type esre1_ktype = { 154 .release = esre_release, 155 .sysfs_ops = &esre_attr_ops, 156 .default_groups = esre1_groups, 157 }; 158 159 160 static struct kobject *esrt_kobj; 161 static struct kset *esrt_kset; 162 163 static int esre_create_sysfs_entry(void *esre, int entry_num) 164 { 165 struct esre_entry *entry; 166 167 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 168 if (!entry) 169 return -ENOMEM; 170 171 entry->kobj.kset = esrt_kset; 172 173 if (esrt->fw_resource_version == 1) { 174 int rc = 0; 175 176 entry->esre.esre1 = esre; 177 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL, 178 "entry%d", entry_num); 179 if (rc) { 180 kobject_put(&entry->kobj); 181 return rc; 182 } 183 } 184 185 list_add_tail(&entry->list, &entry_list); 186 return 0; 187 } 188 189 /* support for displaying ESRT fields at the top level */ 190 #define esrt_attr_decl(name, size, fmt) \ 191 static ssize_t name##_show(struct kobject *kobj, \ 192 struct kobj_attribute *attr, char *buf)\ 193 { \ 194 return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \ 195 } \ 196 \ 197 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400) 198 199 esrt_attr_decl(fw_resource_count, 32, "%u"); 200 esrt_attr_decl(fw_resource_count_max, 32, "%u"); 201 esrt_attr_decl(fw_resource_version, 64, "%llu"); 202 203 static struct attribute *esrt_attrs[] = { 204 &esrt_fw_resource_count.attr, 205 &esrt_fw_resource_count_max.attr, 206 &esrt_fw_resource_version.attr, 207 NULL, 208 }; 209 210 static inline int esrt_table_exists(void) 211 { 212 if (!efi_enabled(EFI_CONFIG_TABLES)) 213 return 0; 214 if (efi.esrt == EFI_INVALID_TABLE_ADDR) 215 return 0; 216 return 1; 217 } 218 219 static umode_t esrt_attr_is_visible(struct kobject *kobj, 220 struct attribute *attr, int n) 221 { 222 if (!esrt_table_exists()) 223 return 0; 224 return attr->mode; 225 } 226 227 static const struct attribute_group esrt_attr_group = { 228 .attrs = esrt_attrs, 229 .is_visible = esrt_attr_is_visible, 230 }; 231 232 /* 233 * remap the table, validate it, mark it reserved and unmap it. 234 */ 235 void __init efi_esrt_init(void) 236 { 237 void *va; 238 struct efi_system_resource_table tmpesrt; 239 size_t size, max, entry_size, entries_size; 240 efi_memory_desc_t md; 241 int rc; 242 phys_addr_t end; 243 244 if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT)) 245 return; 246 247 pr_debug("esrt-init: loading.\n"); 248 if (!esrt_table_exists()) 249 return; 250 251 rc = efi_mem_desc_lookup(efi.esrt, &md); 252 if (rc < 0 || 253 (!(md.attribute & EFI_MEMORY_RUNTIME) && 254 md.type != EFI_BOOT_SERVICES_DATA && 255 md.type != EFI_RUNTIME_SERVICES_DATA && 256 md.type != EFI_ACPI_RECLAIM_MEMORY && 257 md.type != EFI_ACPI_MEMORY_NVS)) { 258 pr_warn("ESRT header is not in the memory map.\n"); 259 return; 260 } 261 262 max = efi_mem_desc_end(&md) - efi.esrt; 263 size = sizeof(*esrt); 264 265 if (max < size) { 266 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n", 267 size, max); 268 return; 269 } 270 271 va = early_memremap(efi.esrt, size); 272 if (!va) { 273 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 274 size); 275 return; 276 } 277 278 memcpy(&tmpesrt, va, sizeof(tmpesrt)); 279 early_memunmap(va, size); 280 281 if (tmpesrt.fw_resource_version != 1) { 282 pr_err("Unsupported ESRT version %lld.\n", 283 tmpesrt.fw_resource_version); 284 return; 285 } 286 287 entry_size = sizeof(struct efi_system_resource_entry_v1); 288 if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) { 289 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n", 290 max - size, entry_size); 291 return; 292 } 293 294 /* 295 * The format doesn't really give us any boundary to test here, 296 * so I'm making up 128 as the max number of individually updatable 297 * components we support. 298 * 128 should be pretty excessive, but there's still some chance 299 * somebody will do that someday and we'll need to raise this. 300 */ 301 if (tmpesrt.fw_resource_count > 128) { 302 pr_err("ESRT says fw_resource_count has very large value %d.\n", 303 tmpesrt.fw_resource_count); 304 return; 305 } 306 307 /* 308 * We know it can't be larger than N * sizeof() here, and N is limited 309 * by the previous test to a small number, so there's no overflow. 310 */ 311 entries_size = tmpesrt.fw_resource_count * entry_size; 312 if (max < size + entries_size) { 313 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n", 314 size, max); 315 return; 316 } 317 318 size += entries_size; 319 320 esrt_data = (phys_addr_t)efi.esrt; 321 esrt_data_size = size; 322 323 end = esrt_data + size; 324 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end); 325 if (md.type == EFI_BOOT_SERVICES_DATA) 326 efi_mem_reserve(esrt_data, esrt_data_size); 327 328 pr_debug("esrt-init: loaded.\n"); 329 } 330 331 static int __init register_entries(void) 332 { 333 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries; 334 int i, rc; 335 336 if (!esrt_table_exists()) 337 return 0; 338 339 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) { 340 void *esre = NULL; 341 if (esrt->fw_resource_version == 1) { 342 esre = &v1_entries[i]; 343 } else { 344 pr_err("Unsupported ESRT version %lld.\n", 345 esrt->fw_resource_version); 346 return -EINVAL; 347 } 348 349 rc = esre_create_sysfs_entry(esre, i); 350 if (rc < 0) { 351 pr_err("ESRT entry creation failed with error %d.\n", 352 rc); 353 return rc; 354 } 355 } 356 return 0; 357 } 358 359 static void cleanup_entry_list(void) 360 { 361 struct esre_entry *entry, *next; 362 363 list_for_each_entry_safe(entry, next, &entry_list, list) { 364 kobject_put(&entry->kobj); 365 } 366 } 367 368 static int __init esrt_sysfs_init(void) 369 { 370 int error; 371 372 pr_debug("esrt-sysfs: loading.\n"); 373 if (!esrt_data || !esrt_data_size) 374 return -ENOSYS; 375 376 esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB); 377 if (!esrt) { 378 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data, 379 esrt_data_size); 380 return -ENOMEM; 381 } 382 383 esrt_kobj = kobject_create_and_add("esrt", efi_kobj); 384 if (!esrt_kobj) { 385 pr_err("Firmware table registration failed.\n"); 386 error = -ENOMEM; 387 goto err; 388 } 389 390 error = sysfs_create_group(esrt_kobj, &esrt_attr_group); 391 if (error) { 392 pr_err("Sysfs attribute export failed with error %d.\n", 393 error); 394 goto err_remove_esrt; 395 } 396 397 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj); 398 if (!esrt_kset) { 399 pr_err("kset creation failed.\n"); 400 error = -ENOMEM; 401 goto err_remove_group; 402 } 403 404 error = register_entries(); 405 if (error) 406 goto err_cleanup_list; 407 408 pr_debug("esrt-sysfs: loaded.\n"); 409 410 return 0; 411 err_cleanup_list: 412 cleanup_entry_list(); 413 kset_unregister(esrt_kset); 414 err_remove_group: 415 sysfs_remove_group(esrt_kobj, &esrt_attr_group); 416 err_remove_esrt: 417 kobject_put(esrt_kobj); 418 err: 419 memunmap(esrt); 420 esrt = NULL; 421 return error; 422 } 423 device_initcall(esrt_sysfs_init); 424 425 /* 426 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>"); 427 MODULE_DESCRIPTION("EFI System Resource Table support"); 428 MODULE_LICENSE("GPL"); 429 */ 430