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 to_entry(struct kobject * kobj)82 static struct esre_entry *to_entry(struct kobject *kobj) 83 { 84 return container_of(kobj, struct esre_entry, kobj); 85 } 86 to_attr(struct attribute * attr)87 static struct esre_attribute *to_attr(struct attribute *attr) 88 { 89 return container_of(attr, struct esre_attribute, attr); 90 } 91 esre_attr_show(struct kobject * kobj,struct attribute * _attr,char * buf)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 return attr->show(entry, buf); 99 } 100 101 static const struct sysfs_ops esre_attr_ops = { 102 .show = esre_attr_show, 103 }; 104 105 /* Generic ESRT Entry ("ESRE") support. */ fw_class_show(struct esre_entry * entry,char * buf)106 static ssize_t fw_class_show(struct esre_entry *entry, char *buf) 107 { 108 char *str = buf; 109 110 efi_guid_to_str(&entry->esre.esre1->fw_class, str); 111 str += strlen(str); 112 str += sprintf(str, "\n"); 113 114 return str - buf; 115 } 116 117 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400); 118 119 #define esre_attr_decl(name, size, fmt) \ 120 static ssize_t name##_show(struct esre_entry *entry, char *buf) \ 121 { \ 122 return sprintf(buf, fmt "\n", \ 123 le##size##_to_cpu(entry->esre.esre1->name)); \ 124 } \ 125 \ 126 static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400) 127 128 esre_attr_decl(fw_type, 32, "%u"); 129 esre_attr_decl(fw_version, 32, "%u"); 130 esre_attr_decl(lowest_supported_fw_version, 32, "%u"); 131 esre_attr_decl(capsule_flags, 32, "0x%x"); 132 esre_attr_decl(last_attempt_version, 32, "%u"); 133 esre_attr_decl(last_attempt_status, 32, "%u"); 134 135 static struct attribute *esre1_attrs[] = { 136 &esre_fw_class.attr, 137 &esre_fw_type.attr, 138 &esre_fw_version.attr, 139 &esre_lowest_supported_fw_version.attr, 140 &esre_capsule_flags.attr, 141 &esre_last_attempt_version.attr, 142 &esre_last_attempt_status.attr, 143 NULL 144 }; 145 ATTRIBUTE_GROUPS(esre1); 146 esre_release(struct kobject * kobj)147 static void esre_release(struct kobject *kobj) 148 { 149 struct esre_entry *entry = to_entry(kobj); 150 151 list_del(&entry->list); 152 kfree(entry); 153 } 154 155 static const struct kobj_type esre1_ktype = { 156 .release = esre_release, 157 .sysfs_ops = &esre_attr_ops, 158 .default_groups = esre1_groups, 159 }; 160 161 162 static struct kobject *esrt_kobj; 163 static struct kset *esrt_kset; 164 esre_create_sysfs_entry(void * esre,int entry_num)165 static int esre_create_sysfs_entry(void *esre, int entry_num) 166 { 167 struct esre_entry *entry; 168 169 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 170 if (!entry) 171 return -ENOMEM; 172 173 entry->kobj.kset = esrt_kset; 174 175 if (esrt->fw_resource_version == 1) { 176 int rc = 0; 177 178 entry->esre.esre1 = esre; 179 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL, 180 "entry%d", entry_num); 181 if (rc) { 182 kobject_put(&entry->kobj); 183 return rc; 184 } 185 } 186 187 list_add_tail(&entry->list, &entry_list); 188 return 0; 189 } 190 191 /* support for displaying ESRT fields at the top level */ 192 #define esrt_attr_decl(name, size, fmt) \ 193 static ssize_t name##_show(struct kobject *kobj, \ 194 struct kobj_attribute *attr, char *buf)\ 195 { \ 196 return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \ 197 } \ 198 \ 199 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400) 200 201 esrt_attr_decl(fw_resource_count, 32, "%u"); 202 esrt_attr_decl(fw_resource_count_max, 32, "%u"); 203 esrt_attr_decl(fw_resource_version, 64, "%llu"); 204 205 static struct attribute *esrt_attrs[] = { 206 &esrt_fw_resource_count.attr, 207 &esrt_fw_resource_count_max.attr, 208 &esrt_fw_resource_version.attr, 209 NULL, 210 }; 211 esrt_table_exists(void)212 static inline int esrt_table_exists(void) 213 { 214 if (!efi_enabled(EFI_CONFIG_TABLES)) 215 return 0; 216 if (efi.esrt == EFI_INVALID_TABLE_ADDR) 217 return 0; 218 return 1; 219 } 220 esrt_attr_is_visible(struct kobject * kobj,struct attribute * attr,int n)221 static umode_t esrt_attr_is_visible(struct kobject *kobj, 222 struct attribute *attr, int n) 223 { 224 if (!esrt_table_exists()) 225 return 0; 226 return attr->mode; 227 } 228 229 static const struct attribute_group esrt_attr_group = { 230 .attrs = esrt_attrs, 231 .is_visible = esrt_attr_is_visible, 232 }; 233 234 /* 235 * remap the table, validate it, mark it reserved and unmap it. 236 */ efi_esrt_init(void)237 void __init efi_esrt_init(void) 238 { 239 void *va; 240 struct efi_system_resource_table tmpesrt; 241 size_t size, max, entry_size, entries_size; 242 efi_memory_desc_t md; 243 int rc; 244 phys_addr_t end; 245 246 if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT)) 247 return; 248 249 pr_debug("esrt-init: loading.\n"); 250 if (!esrt_table_exists()) 251 return; 252 253 rc = efi_mem_desc_lookup(efi.esrt, &md); 254 if (rc < 0 || 255 (!(md.attribute & EFI_MEMORY_RUNTIME) && 256 md.type != EFI_BOOT_SERVICES_DATA && 257 md.type != EFI_RUNTIME_SERVICES_DATA && 258 md.type != EFI_ACPI_RECLAIM_MEMORY && 259 md.type != EFI_ACPI_MEMORY_NVS)) { 260 pr_warn("ESRT header is not in the memory map.\n"); 261 return; 262 } 263 264 max = efi_mem_desc_end(&md) - efi.esrt; 265 size = sizeof(*esrt); 266 267 if (max < size) { 268 pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n", 269 size, max); 270 return; 271 } 272 273 va = early_memremap(efi.esrt, size); 274 if (!va) { 275 pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt, 276 size); 277 return; 278 } 279 280 memcpy(&tmpesrt, va, sizeof(tmpesrt)); 281 early_memunmap(va, size); 282 283 if (tmpesrt.fw_resource_version != 1) { 284 pr_err("Unsupported ESRT version %lld.\n", 285 tmpesrt.fw_resource_version); 286 return; 287 } 288 289 entry_size = sizeof(struct efi_system_resource_entry_v1); 290 if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) { 291 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n", 292 max - size, entry_size); 293 return; 294 } 295 296 /* 297 * The format doesn't really give us any boundary to test here, 298 * so I'm making up 128 as the max number of individually updatable 299 * components we support. 300 * 128 should be pretty excessive, but there's still some chance 301 * somebody will do that someday and we'll need to raise this. 302 */ 303 if (tmpesrt.fw_resource_count > 128) { 304 pr_err("ESRT says fw_resource_count has very large value %d.\n", 305 tmpesrt.fw_resource_count); 306 return; 307 } 308 309 /* 310 * We know it can't be larger than N * sizeof() here, and N is limited 311 * by the previous test to a small number, so there's no overflow. 312 */ 313 entries_size = tmpesrt.fw_resource_count * entry_size; 314 if (max < size + entries_size) { 315 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n", 316 size, max); 317 return; 318 } 319 320 size += entries_size; 321 322 esrt_data = (phys_addr_t)efi.esrt; 323 esrt_data_size = size; 324 325 end = esrt_data + size; 326 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end); 327 if (md.type == EFI_BOOT_SERVICES_DATA) 328 efi_mem_reserve(esrt_data, esrt_data_size); 329 330 pr_debug("esrt-init: loaded.\n"); 331 } 332 register_entries(void)333 static int __init register_entries(void) 334 { 335 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries; 336 int i, rc; 337 338 if (!esrt_table_exists()) 339 return 0; 340 341 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) { 342 void *esre = NULL; 343 if (esrt->fw_resource_version == 1) { 344 esre = &v1_entries[i]; 345 } else { 346 pr_err("Unsupported ESRT version %lld.\n", 347 esrt->fw_resource_version); 348 return -EINVAL; 349 } 350 351 rc = esre_create_sysfs_entry(esre, i); 352 if (rc < 0) { 353 pr_err("ESRT entry creation failed with error %d.\n", 354 rc); 355 return rc; 356 } 357 } 358 return 0; 359 } 360 cleanup_entry_list(void)361 static void cleanup_entry_list(void) 362 { 363 struct esre_entry *entry, *next; 364 365 list_for_each_entry_safe(entry, next, &entry_list, list) { 366 kobject_put(&entry->kobj); 367 } 368 } 369 esrt_sysfs_init(void)370 static int __init esrt_sysfs_init(void) 371 { 372 int error; 373 374 pr_debug("esrt-sysfs: loading.\n"); 375 if (!esrt_data || !esrt_data_size) 376 return -ENOSYS; 377 378 esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB); 379 if (!esrt) { 380 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data, 381 esrt_data_size); 382 return -ENOMEM; 383 } 384 385 esrt_kobj = kobject_create_and_add("esrt", efi_kobj); 386 if (!esrt_kobj) { 387 pr_err("Firmware table registration failed.\n"); 388 error = -ENOMEM; 389 goto err; 390 } 391 392 error = sysfs_create_group(esrt_kobj, &esrt_attr_group); 393 if (error) { 394 pr_err("Sysfs attribute export failed with error %d.\n", 395 error); 396 goto err_remove_esrt; 397 } 398 399 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj); 400 if (!esrt_kset) { 401 pr_err("kset creation failed.\n"); 402 error = -ENOMEM; 403 goto err_remove_group; 404 } 405 406 error = register_entries(); 407 if (error) 408 goto err_cleanup_list; 409 410 pr_debug("esrt-sysfs: loaded.\n"); 411 412 return 0; 413 err_cleanup_list: 414 cleanup_entry_list(); 415 kset_unregister(esrt_kset); 416 err_remove_group: 417 sysfs_remove_group(esrt_kobj, &esrt_attr_group); 418 err_remove_esrt: 419 kobject_put(esrt_kobj); 420 err: 421 memunmap(esrt); 422 esrt = NULL; 423 return error; 424 } 425 device_initcall(esrt_sysfs_init); 426 427 /* 428 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>"); 429 MODULE_DESCRIPTION("EFI System Resource Table support"); 430 MODULE_LICENSE("GPL"); 431 */ 432