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 };
149 ATTRIBUTE_GROUPS(esre1);
150
esre_release(struct kobject * kobj)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
esre_create_sysfs_entry(void * esre,int entry_num)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
esrt_table_exists(void)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
esrt_attr_is_visible(struct kobject * kobj,struct attribute * attr,int n)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 */
efi_esrt_init(void)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
register_entries(void)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
cleanup_entry_list(void)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
esrt_sysfs_init(void)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