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 /* 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. */
fw_class_show(struct esre_entry * entry,char * buf)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 };
esre_release(struct kobject * kobj)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
esre_create_sysfs_entry(void * esre,int entry_num)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
esrt_table_exists(void)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
esrt_attr_is_visible(struct kobject * kobj,struct attribute * attr,int n)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 */
efi_esrt_init(void)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
register_entries(void)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
cleanup_entry_list(void)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
esrt_sysfs_init(void)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