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
