xref: /openbmc/linux/drivers/firmware/efi/esrt.c (revision 002dff36)
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);
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. */
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 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 
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 
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 
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  */
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 
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 
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 
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