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 ATTRIBUTE_GROUPS(esre1); 150 151 static void esre_release(struct kobject *kobj) 152 { 153 struct esre_entry *entry = to_entry(kobj); 154 155 list_del(&entry->list); 156 kfree(entry); 157 } 158 159 static struct kobj_type esre1_ktype = { 160 .release = esre_release, 161 .sysfs_ops = &esre_attr_ops, 162 .default_groups = esre1_groups, 163 }; 164 165 166 static struct kobject *esrt_kobj; 167 static struct kset *esrt_kset; 168 169 static int esre_create_sysfs_entry(void *esre, int entry_num) 170 { 171 struct esre_entry *entry; 172 173 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 174 if (!entry) 175 return -ENOMEM; 176 177 entry->kobj.kset = esrt_kset; 178 179 if (esrt->fw_resource_version == 1) { 180 int rc = 0; 181 182 entry->esre.esre1 = esre; 183 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL, 184 "entry%d", entry_num); 185 if (rc) { 186 kobject_put(&entry->kobj); 187 return rc; 188 } 189 } 190 191 list_add_tail(&entry->list, &entry_list); 192 return 0; 193 } 194 195 /* support for displaying ESRT fields at the top level */ 196 #define esrt_attr_decl(name, size, fmt) \ 197 static ssize_t name##_show(struct kobject *kobj, \ 198 struct kobj_attribute *attr, char *buf)\ 199 { \ 200 return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \ 201 } \ 202 \ 203 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400) 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 size_t size, max, entry_size, entries_size; 246 efi_memory_desc_t md; 247 int rc; 248 phys_addr_t end; 249 250 if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT)) 251 return; 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 (!(md.attribute & EFI_MEMORY_RUNTIME) && 260 md.type != EFI_BOOT_SERVICES_DATA && 261 md.type != EFI_RUNTIME_SERVICES_DATA && 262 md.type != EFI_ACPI_RECLAIM_MEMORY && 263 md.type != EFI_ACPI_MEMORY_NVS)) { 264 pr_warn("ESRT header is not in the memory map.\n"); 265 return; 266 } 267 268 max = efi_mem_desc_end(&md) - efi.esrt; 269 size = sizeof(*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 early_memunmap(va, size); 286 287 if (tmpesrt.fw_resource_version != 1) { 288 pr_err("Unsupported ESRT version %lld.\n", 289 tmpesrt.fw_resource_version); 290 return; 291 } 292 293 entry_size = sizeof(struct efi_system_resource_entry_v1); 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 return; 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 return; 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 return; 322 } 323 324 size += entries_size; 325 326 esrt_data = (phys_addr_t)efi.esrt; 327 esrt_data_size = size; 328 329 end = esrt_data + size; 330 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end); 331 if (md.type == EFI_BOOT_SERVICES_DATA) 332 efi_mem_reserve(esrt_data, esrt_data_size); 333 334 pr_debug("esrt-init: loaded.\n"); 335 } 336 337 static int __init register_entries(void) 338 { 339 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries; 340 int i, rc; 341 342 if (!esrt_table_exists()) 343 return 0; 344 345 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) { 346 void *esre = NULL; 347 if (esrt->fw_resource_version == 1) { 348 esre = &v1_entries[i]; 349 } else { 350 pr_err("Unsupported ESRT version %lld.\n", 351 esrt->fw_resource_version); 352 return -EINVAL; 353 } 354 355 rc = esre_create_sysfs_entry(esre, i); 356 if (rc < 0) { 357 pr_err("ESRT entry creation failed with error %d.\n", 358 rc); 359 return rc; 360 } 361 } 362 return 0; 363 } 364 365 static void cleanup_entry_list(void) 366 { 367 struct esre_entry *entry, *next; 368 369 list_for_each_entry_safe(entry, next, &entry_list, list) { 370 kobject_put(&entry->kobj); 371 } 372 } 373 374 static int __init esrt_sysfs_init(void) 375 { 376 int error; 377 378 pr_debug("esrt-sysfs: loading.\n"); 379 if (!esrt_data || !esrt_data_size) 380 return -ENOSYS; 381 382 esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB); 383 if (!esrt) { 384 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data, 385 esrt_data_size); 386 return -ENOMEM; 387 } 388 389 esrt_kobj = kobject_create_and_add("esrt", efi_kobj); 390 if (!esrt_kobj) { 391 pr_err("Firmware table registration failed.\n"); 392 error = -ENOMEM; 393 goto err; 394 } 395 396 error = sysfs_create_group(esrt_kobj, &esrt_attr_group); 397 if (error) { 398 pr_err("Sysfs attribute export failed with error %d.\n", 399 error); 400 goto err_remove_esrt; 401 } 402 403 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj); 404 if (!esrt_kset) { 405 pr_err("kset creation failed.\n"); 406 error = -ENOMEM; 407 goto err_remove_group; 408 } 409 410 error = register_entries(); 411 if (error) 412 goto err_cleanup_list; 413 414 pr_debug("esrt-sysfs: loaded.\n"); 415 416 return 0; 417 err_cleanup_list: 418 cleanup_entry_list(); 419 kset_unregister(esrt_kset); 420 err_remove_group: 421 sysfs_remove_group(esrt_kobj, &esrt_attr_group); 422 err_remove_esrt: 423 kobject_put(esrt_kobj); 424 err: 425 memunmap(esrt); 426 esrt = NULL; 427 return error; 428 } 429 device_initcall(esrt_sysfs_init); 430 431 /* 432 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>"); 433 MODULE_DESCRIPTION("EFI System Resource Table support"); 434 MODULE_LICENSE("GPL"); 435 */ 436