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 | |
82 | static struct esre_entry *to_entry(struct kobject *kobj) |
83 | { |
84 | return container_of(kobj, struct esre_entry, kobj); |
85 | } |
86 | |
87 | static struct esre_attribute *to_attr(struct attribute *attr) |
88 | { |
89 | return container_of(attr, struct esre_attribute, attr); |
90 | } |
91 | |
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: _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. */ |
106 | static ssize_t fw_class_show(struct esre_entry *entry, char *buf) |
107 | { |
108 | char *str = buf; |
109 | |
110 | efi_guid_to_str(guid: &entry->esre.esre1->fw_class, out: str); |
111 | str += strlen(str); |
112 | str += sprintf(buf: str, fmt: "\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 | |
147 | static void esre_release(struct kobject *kobj) |
148 | { |
149 | struct esre_entry *entry = to_entry(kobj); |
150 | |
151 | list_del(entry: &entry->list); |
152 | kfree(objp: 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 | |
165 | static int esre_create_sysfs_entry(void *esre, int entry_num) |
166 | { |
167 | struct esre_entry *entry; |
168 | |
169 | entry = kzalloc(size: 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(kobj: &entry->kobj, ktype: &esre1_ktype, NULL, |
180 | fmt: "entry%d" , entry_num); |
181 | if (rc) { |
182 | kobject_put(kobj: &entry->kobj); |
183 | return rc; |
184 | } |
185 | } |
186 | |
187 | list_add_tail(new: &entry->list, head: &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 | |
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 | |
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 | */ |
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(phys_addr: efi.esrt, out_md: &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: &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(phys_addr: 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(addr: 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(addr: esrt_data, size: esrt_data_size); |
329 | |
330 | pr_debug("esrt-init: loaded.\n" ); |
331 | } |
332 | |
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, entry_num: 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 | |
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(kobj: &entry->kobj); |
367 | } |
368 | } |
369 | |
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(offset: esrt_data, size: esrt_data_size, flags: 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(name: "esrt" , parent: 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(kobj: esrt_kobj, grp: &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(name: "entries" , NULL, parent_kobj: 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(kset: esrt_kset); |
416 | err_remove_group: |
417 | sysfs_remove_group(kobj: esrt_kobj, grp: &esrt_attr_group); |
418 | err_remove_esrt: |
419 | kobject_put(kobj: esrt_kobj); |
420 | err: |
421 | memunmap(addr: 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 | |