1 /*
2 * esrt.c
3 *
4 * This module exports EFI System Resource Table (ESRT) entries into userspace
5 * through the sysfs file system. The ESRT provides a read-only catalog of
6 * system components for which the system accepts firmware upgrades via UEFI's
7 * "Capsule Update" feature. This module allows userland utilities to evaluate
8 * what firmware updates can be applied to this system, and potentially arrange
9 * for those updates to occur.
10 *
11 * Data is currently found below /sys/firmware/efi/esrt/...
12 */
13 #define pr_fmt(fmt) "esrt: " fmt
14
15 #include <linux/capability.h>
16 #include <linux/device.h>
17 #include <linux/efi.h>
18 #include <linux/init.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21 #include <linux/kobject.h>
22 #include <linux/list.h>
23 #include <linux/memblock.h>
24 #include <linux/slab.h>
25 #include <linux/types.h>
26
27 #include <asm/io.h>
28 #include <asm/early_ioremap.h>
29
30 struct efi_system_resource_entry_v1 {
31 efi_guid_t fw_class;
32 u32 fw_type;
33 u32 fw_version;
34 u32 lowest_supported_fw_version;
35 u32 capsule_flags;
36 u32 last_attempt_version;
37 u32 last_attempt_status;
38 };
39
40 /*
41 * _count and _version are what they seem like. _max is actually just
42 * accounting info for the firmware when creating the table; it should never
43 * have been exposed to us. To wit, the spec says:
44 * The maximum number of resource array entries that can be within the
45 * table without reallocating the table, must not be zero.
46 * Since there's no guidance about what that means in terms of memory layout,
47 * it means nothing to us.
48 */
49 struct efi_system_resource_table {
50 u32 fw_resource_count;
51 u32 fw_resource_count_max;
52 u64 fw_resource_version;
53 u8 entries[];
54 };
55
56 static phys_addr_t esrt_data;
57 static size_t esrt_data_size;
58
59 static struct efi_system_resource_table *esrt;
60
61 struct esre_entry {
62 union {
63 struct efi_system_resource_entry_v1 *esre1;
64 } esre;
65
66 struct kobject kobj;
67 struct list_head list;
68 };
69
70 /* global list of esre_entry. */
71 static LIST_HEAD(entry_list);
72
73 /* entry attribute */
74 struct esre_attribute {
75 struct attribute attr;
76 ssize_t (*show)(struct esre_entry *entry, char *buf);
77 ssize_t (*store)(struct esre_entry *entry,
78 const char *buf, size_t count);
79 };
80
to_entry(struct kobject * kobj)81 static struct esre_entry *to_entry(struct kobject *kobj)
82 {
83 return container_of(kobj, struct esre_entry, kobj);
84 }
85
to_attr(struct attribute * attr)86 static struct esre_attribute *to_attr(struct attribute *attr)
87 {
88 return container_of(attr, struct esre_attribute, attr);
89 }
90
esre_attr_show(struct kobject * kobj,struct attribute * _attr,char * buf)91 static ssize_t esre_attr_show(struct kobject *kobj,
92 struct attribute *_attr, char *buf)
93 {
94 struct esre_entry *entry = to_entry(kobj);
95 struct esre_attribute *attr = to_attr(_attr);
96
97 /* Don't tell normal users what firmware versions we've got... */
98 if (!capable(CAP_SYS_ADMIN))
99 return -EACCES;
100
101 return attr->show(entry, buf);
102 }
103
104 static const struct sysfs_ops esre_attr_ops = {
105 .show = esre_attr_show,
106 };
107
108 /* Generic ESRT Entry ("ESRE") support. */
fw_class_show(struct esre_entry * entry,char * buf)109 static ssize_t fw_class_show(struct esre_entry *entry, char *buf)
110 {
111 char *str = buf;
112
113 efi_guid_to_str(&entry->esre.esre1->fw_class, str);
114 str += strlen(str);
115 str += sprintf(str, "\n");
116
117 return str - buf;
118 }
119
120 static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400);
121
122 #define esre_attr_decl(name, size, fmt) \
123 static ssize_t name##_show(struct esre_entry *entry, char *buf) \
124 { \
125 return sprintf(buf, fmt "\n", \
126 le##size##_to_cpu(entry->esre.esre1->name)); \
127 } \
128 \
129 static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400)
130
131 esre_attr_decl(fw_type, 32, "%u");
132 esre_attr_decl(fw_version, 32, "%u");
133 esre_attr_decl(lowest_supported_fw_version, 32, "%u");
134 esre_attr_decl(capsule_flags, 32, "0x%x");
135 esre_attr_decl(last_attempt_version, 32, "%u");
136 esre_attr_decl(last_attempt_status, 32, "%u");
137
138 static struct attribute *esre1_attrs[] = {
139 &esre_fw_class.attr,
140 &esre_fw_type.attr,
141 &esre_fw_version.attr,
142 &esre_lowest_supported_fw_version.attr,
143 &esre_capsule_flags.attr,
144 &esre_last_attempt_version.attr,
145 &esre_last_attempt_status.attr,
146 NULL
147 };
esre_release(struct kobject * kobj)148 static void esre_release(struct kobject *kobj)
149 {
150 struct esre_entry *entry = to_entry(kobj);
151
152 list_del(&entry->list);
153 kfree(entry);
154 }
155
156 static struct kobj_type esre1_ktype = {
157 .release = esre_release,
158 .sysfs_ops = &esre_attr_ops,
159 .default_attrs = esre1_attrs,
160 };
161
162
163 static struct kobject *esrt_kobj;
164 static struct kset *esrt_kset;
165
esre_create_sysfs_entry(void * esre,int entry_num)166 static int esre_create_sysfs_entry(void *esre, int entry_num)
167 {
168 struct esre_entry *entry;
169
170 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
171 if (!entry)
172 return -ENOMEM;
173
174 entry->kobj.kset = esrt_kset;
175
176 if (esrt->fw_resource_version == 1) {
177 int rc = 0;
178
179 entry->esre.esre1 = esre;
180 rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
181 "entry%d", entry_num);
182 if (rc) {
183 kfree(entry);
184 return rc;
185 }
186 }
187
188 list_add_tail(&entry->list, &entry_list);
189 return 0;
190 }
191
192 /* support for displaying ESRT fields at the top level */
193 #define esrt_attr_decl(name, size, fmt) \
194 static ssize_t name##_show(struct kobject *kobj, \
195 struct kobj_attribute *attr, char *buf)\
196 { \
197 return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
198 } \
199 \
200 static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400)
201
202 esrt_attr_decl(fw_resource_count, 32, "%u");
203 esrt_attr_decl(fw_resource_count_max, 32, "%u");
204 esrt_attr_decl(fw_resource_version, 64, "%llu");
205
206 static struct attribute *esrt_attrs[] = {
207 &esrt_fw_resource_count.attr,
208 &esrt_fw_resource_count_max.attr,
209 &esrt_fw_resource_version.attr,
210 NULL,
211 };
212
esrt_table_exists(void)213 static inline int esrt_table_exists(void)
214 {
215 if (!efi_enabled(EFI_CONFIG_TABLES))
216 return 0;
217 if (efi.esrt == EFI_INVALID_TABLE_ADDR)
218 return 0;
219 return 1;
220 }
221
esrt_attr_is_visible(struct kobject * kobj,struct attribute * attr,int n)222 static umode_t esrt_attr_is_visible(struct kobject *kobj,
223 struct attribute *attr, int n)
224 {
225 if (!esrt_table_exists())
226 return 0;
227 return attr->mode;
228 }
229
230 static const struct attribute_group esrt_attr_group = {
231 .attrs = esrt_attrs,
232 .is_visible = esrt_attr_is_visible,
233 };
234
235 /*
236 * remap the table, validate it, mark it reserved and unmap it.
237 */
efi_esrt_init(void)238 void __init efi_esrt_init(void)
239 {
240 void *va;
241 struct efi_system_resource_table tmpesrt;
242 struct efi_system_resource_entry_v1 *v1_entries;
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 pr_debug("esrt-init: loading.\n");
249 if (!esrt_table_exists())
250 return;
251
252 rc = efi_mem_desc_lookup(efi.esrt, &md);
253 if (rc < 0 ||
254 (!(md.attribute & EFI_MEMORY_RUNTIME) &&
255 md.type != EFI_BOOT_SERVICES_DATA &&
256 md.type != EFI_RUNTIME_SERVICES_DATA)) {
257 pr_warn("ESRT header is not in the memory map.\n");
258 return;
259 }
260
261 max = efi_mem_desc_end(&md);
262 if (max < efi.esrt) {
263 pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n",
264 (void *)efi.esrt, (void *)max);
265 return;
266 }
267
268 size = sizeof(*esrt);
269 max -= efi.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 entry_size = sizeof (*v1_entries);
289 } else {
290 pr_err("Unsupported ESRT version %lld.\n",
291 tmpesrt.fw_resource_version);
292 return;
293 }
294
295 if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
296 pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
297 max - size, entry_size);
298 return;
299 }
300
301 /*
302 * The format doesn't really give us any boundary to test here,
303 * so I'm making up 128 as the max number of individually updatable
304 * components we support.
305 * 128 should be pretty excessive, but there's still some chance
306 * somebody will do that someday and we'll need to raise this.
307 */
308 if (tmpesrt.fw_resource_count > 128) {
309 pr_err("ESRT says fw_resource_count has very large value %d.\n",
310 tmpesrt.fw_resource_count);
311 return;
312 }
313
314 /*
315 * We know it can't be larger than N * sizeof() here, and N is limited
316 * by the previous test to a small number, so there's no overflow.
317 */
318 entries_size = tmpesrt.fw_resource_count * entry_size;
319 if (max < size + entries_size) {
320 pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
321 size, max);
322 return;
323 }
324
325 size += entries_size;
326
327 esrt_data = (phys_addr_t)efi.esrt;
328 esrt_data_size = size;
329
330 end = esrt_data + size;
331 pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
332 if (md.type == EFI_BOOT_SERVICES_DATA)
333 efi_mem_reserve(esrt_data, esrt_data_size);
334
335 pr_debug("esrt-init: loaded.\n");
336 }
337
register_entries(void)338 static int __init register_entries(void)
339 {
340 struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
341 int i, rc;
342
343 if (!esrt_table_exists())
344 return 0;
345
346 for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
347 void *esre = NULL;
348 if (esrt->fw_resource_version == 1) {
349 esre = &v1_entries[i];
350 } else {
351 pr_err("Unsupported ESRT version %lld.\n",
352 esrt->fw_resource_version);
353 return -EINVAL;
354 }
355
356 rc = esre_create_sysfs_entry(esre, i);
357 if (rc < 0) {
358 pr_err("ESRT entry creation failed with error %d.\n",
359 rc);
360 return rc;
361 }
362 }
363 return 0;
364 }
365
cleanup_entry_list(void)366 static void cleanup_entry_list(void)
367 {
368 struct esre_entry *entry, *next;
369
370 list_for_each_entry_safe(entry, next, &entry_list, list) {
371 kobject_put(&entry->kobj);
372 }
373 }
374
esrt_sysfs_init(void)375 static int __init esrt_sysfs_init(void)
376 {
377 int error;
378
379 pr_debug("esrt-sysfs: loading.\n");
380 if (!esrt_data || !esrt_data_size)
381 return -ENOSYS;
382
383 esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
384 if (!esrt) {
385 pr_err("memremap(%pa, %zu) failed.\n", &esrt_data,
386 esrt_data_size);
387 return -ENOMEM;
388 }
389
390 esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
391 if (!esrt_kobj) {
392 pr_err("Firmware table registration failed.\n");
393 error = -ENOMEM;
394 goto err;
395 }
396
397 error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
398 if (error) {
399 pr_err("Sysfs attribute export failed with error %d.\n",
400 error);
401 goto err_remove_esrt;
402 }
403
404 esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
405 if (!esrt_kset) {
406 pr_err("kset creation failed.\n");
407 error = -ENOMEM;
408 goto err_remove_group;
409 }
410
411 error = register_entries();
412 if (error)
413 goto err_cleanup_list;
414
415 pr_debug("esrt-sysfs: loaded.\n");
416
417 return 0;
418 err_cleanup_list:
419 cleanup_entry_list();
420 kset_unregister(esrt_kset);
421 err_remove_group:
422 sysfs_remove_group(esrt_kobj, &esrt_attr_group);
423 err_remove_esrt:
424 kobject_put(esrt_kobj);
425 err:
426 memunmap(esrt);
427 esrt = NULL;
428 return error;
429 }
430 device_initcall(esrt_sysfs_init);
431
432 /*
433 MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
434 MODULE_DESCRIPTION("EFI System Resource Table support");
435 MODULE_LICENSE("GPL");
436 */
437
