efivars.c revision bafc84d539c0ffa916037840df54428623abc3e6 
1/*
2 * Originally from efivars.c,
3 *
4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
6 *
7 * This code takes all variables accessible from EFI runtime and
8 *  exports them via sysfs
9 *
10 *  This program is free software; you can redistribute it and/or modify
11 *  it under the terms of the GNU General Public License as published by
12 *  the Free Software Foundation; either version 2 of the License, or
13 *  (at your option) any later version.
14 *
15 *  This program is distributed in the hope that it will be useful,
16 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
17 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18 *  GNU General Public License for more details.
19 *
20 *  You should have received a copy of the GNU General Public License
21 *  along with this program; if not, write to the Free Software
22 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
23 *
24 * Changelog:
25 *
26 *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
27 *   remove check for efi_enabled in exit
28 *   add MODULE_VERSION
29 *
30 *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
31 *   minor bug fixes
32 *
33 *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
34 *   converted driver to export variable information via sysfs
35 *   and moved to drivers/firmware directory
36 *   bumped revision number to v0.07 to reflect conversion & move
37 *
38 *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
39 *   fix locking per Peter Chubb's findings
40 *
41 *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
42 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
43 *
44 *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
45 *   use list_for_each_safe when deleting vars.
46 *   remove ifdef CONFIG_SMP around include <linux/smp.h>
47 *   v0.04 release to linux-ia64@linuxia64.org
48 *
49 *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
50 *   Moved vars from /proc/efi to /proc/efi/vars, and made
51 *   efi.c own the /proc/efi directory.
52 *   v0.03 release to linux-ia64@linuxia64.org
53 *
54 *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
55 *   At the request of Stephane, moved ownership of /proc/efi
56 *   to efi.c, and now efivars lives under /proc/efi/vars.
57 *
58 *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
59 *   Feedback received from Stephane Eranian incorporated.
60 *   efivar_write() checks copy_from_user() return value.
61 *   efivar_read/write() returns proper errno.
62 *   v0.02 release to linux-ia64@linuxia64.org
63 *
64 *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
65 *   v0.01 release to linux-ia64@linuxia64.org
66 */
67
68#include <linux/efi.h>
69#include <linux/module.h>
70#include <linux/slab.h>
71#include <linux/ucs2_string.h>
72
73#define EFIVARS_VERSION "0.08"
74#define EFIVARS_DATE "2004-May-17"
75
76MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
77MODULE_DESCRIPTION("sysfs interface to EFI Variables");
78MODULE_LICENSE("GPL");
79MODULE_VERSION(EFIVARS_VERSION);
80
81LIST_HEAD(efivar_sysfs_list);
82EXPORT_SYMBOL_GPL(efivar_sysfs_list);
83
84static struct kset *efivars_kset;
85
86static struct bin_attribute *efivars_new_var;
87static struct bin_attribute *efivars_del_var;
88
89struct efivar_attribute {
90	struct attribute attr;
91	ssize_t (*show) (struct efivar_entry *entry, char *buf);
92	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
93};
94
95#define EFIVAR_ATTR(_name, _mode, _show, _store) \
96struct efivar_attribute efivar_attr_##_name = { \
97	.attr = {.name = __stringify(_name), .mode = _mode}, \
98	.show = _show, \
99	.store = _store, \
100};
101
102#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
103#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)
104
105/*
106 * Prototype for sysfs creation function
107 */
108static int
109efivar_create_sysfs_entry(struct efivar_entry *new_var);
110
111static ssize_t
112efivar_guid_read(struct efivar_entry *entry, char *buf)
113{
114	struct efi_variable *var = &entry->var;
115	char *str = buf;
116
117	if (!entry || !buf)
118		return 0;
119
120	efi_guid_unparse(&var->VendorGuid, str);
121	str += strlen(str);
122	str += sprintf(str, "\n");
123
124	return str - buf;
125}
126
127static ssize_t
128efivar_attr_read(struct efivar_entry *entry, char *buf)
129{
130	struct efi_variable *var = &entry->var;
131	char *str = buf;
132
133	if (!entry || !buf)
134		return -EINVAL;
135
136	var->DataSize = 1024;
137	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
138		return -EIO;
139
140	if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
141		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
142	if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
143		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
144	if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
145		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
146	if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
147		str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
148	if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
149		str += sprintf(str,
150			"EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
151	if (var->Attributes &
152			EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
153		str += sprintf(str,
154			"EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
155	if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
156		str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
157	return str - buf;
158}
159
160static ssize_t
161efivar_size_read(struct efivar_entry *entry, char *buf)
162{
163	struct efi_variable *var = &entry->var;
164	char *str = buf;
165
166	if (!entry || !buf)
167		return -EINVAL;
168
169	var->DataSize = 1024;
170	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
171		return -EIO;
172
173	str += sprintf(str, "0x%lx\n", var->DataSize);
174	return str - buf;
175}
176
177static ssize_t
178efivar_data_read(struct efivar_entry *entry, char *buf)
179{
180	struct efi_variable *var = &entry->var;
181
182	if (!entry || !buf)
183		return -EINVAL;
184
185	var->DataSize = 1024;
186	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
187		return -EIO;
188
189	memcpy(buf, var->Data, var->DataSize);
190	return var->DataSize;
191}
192/*
193 * We allow each variable to be edited via rewriting the
194 * entire efi variable structure.
195 */
196static ssize_t
197efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
198{
199	struct efi_variable *new_var, *var = &entry->var;
200	efi_char16_t *name;
201	unsigned long size;
202	efi_guid_t vendor;
203	u32 attributes;
204	u8 *data;
205	int err;
206
207	if (count != sizeof(struct efi_variable))
208		return -EINVAL;
209
210	new_var = (struct efi_variable *)buf;
211
212	attributes = new_var->Attributes;
213	vendor = new_var->VendorGuid;
214	name = new_var->VariableName;
215	size = new_var->DataSize;
216	data = new_var->Data;
217
218	/*
219	 * If only updating the variable data, then the name
220	 * and guid should remain the same
221	 */
222	if (memcmp(name, var->VariableName, sizeof(var->VariableName)) ||
223		efi_guidcmp(vendor, var->VendorGuid)) {
224		printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
225		return -EINVAL;
226	}
227
228	if ((size <= 0) || (attributes == 0)){
229		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
230		return -EINVAL;
231	}
232
233	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
234	    efivar_validate(new_var, data, size) == false) {
235		printk(KERN_ERR "efivars: Malformed variable content\n");
236		return -EINVAL;
237	}
238
239	memcpy(&entry->var, new_var, count);
240
241	err = efivar_entry_set(entry, attributes, size, data, NULL);
242	if (err) {
243		printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
244		return -EIO;
245	}
246
247	return count;
248}
249
250static ssize_t
251efivar_show_raw(struct efivar_entry *entry, char *buf)
252{
253	struct efi_variable *var = &entry->var;
254
255	if (!entry || !buf)
256		return 0;
257
258	var->DataSize = 1024;
259	if (efivar_entry_get(entry, &entry->var.Attributes,
260			     &entry->var.DataSize, entry->var.Data))
261		return -EIO;
262
263	memcpy(buf, var, sizeof(*var));
264
265	return sizeof(*var);
266}
267
268/*
269 * Generic read/write functions that call the specific functions of
270 * the attributes...
271 */
272static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
273				char *buf)
274{
275	struct efivar_entry *var = to_efivar_entry(kobj);
276	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
277	ssize_t ret = -EIO;
278
279	if (!capable(CAP_SYS_ADMIN))
280		return -EACCES;
281
282	if (efivar_attr->show) {
283		ret = efivar_attr->show(var, buf);
284	}
285	return ret;
286}
287
288static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
289				const char *buf, size_t count)
290{
291	struct efivar_entry *var = to_efivar_entry(kobj);
292	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
293	ssize_t ret = -EIO;
294
295	if (!capable(CAP_SYS_ADMIN))
296		return -EACCES;
297
298	if (efivar_attr->store)
299		ret = efivar_attr->store(var, buf, count);
300
301	return ret;
302}
303
304static const struct sysfs_ops efivar_attr_ops = {
305	.show = efivar_attr_show,
306	.store = efivar_attr_store,
307};
308
309static void efivar_release(struct kobject *kobj)
310{
311	struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
312	kfree(var);
313}
314
315static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
316static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
317static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
318static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
319static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
320
321static struct attribute *def_attrs[] = {
322	&efivar_attr_guid.attr,
323	&efivar_attr_size.attr,
324	&efivar_attr_attributes.attr,
325	&efivar_attr_data.attr,
326	&efivar_attr_raw_var.attr,
327	NULL,
328};
329
330static struct kobj_type efivar_ktype = {
331	.release = efivar_release,
332	.sysfs_ops = &efivar_attr_ops,
333	.default_attrs = def_attrs,
334};
335
336static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
337			     struct bin_attribute *bin_attr,
338			     char *buf, loff_t pos, size_t count)
339{
340	struct efi_variable *new_var = (struct efi_variable *)buf;
341	struct efivar_entry *new_entry;
342	unsigned long size;
343	u32 attributes;
344	u8 *data;
345	int err;
346
347	if (!capable(CAP_SYS_ADMIN))
348		return -EACCES;
349
350	attributes = new_var->Attributes;
351	size = new_var->DataSize;
352	data = new_var->Data;
353
354	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
355	    efivar_validate(new_var, data, size) == false) {
356		printk(KERN_ERR "efivars: Malformed variable content\n");
357		return -EINVAL;
358	}
359
360	new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
361	if (!new_entry)
362		return -ENOMEM;
363
364	memcpy(&new_entry->var, new_var, sizeof(*new_var));
365
366	err = efivar_entry_set(new_entry, attributes, size,
367			       data, &efivar_sysfs_list);
368	if (err) {
369		if (err == -EEXIST)
370			err = -EINVAL;
371		goto out;
372	}
373
374	if (efivar_create_sysfs_entry(new_entry)) {
375		printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
376		kfree(new_entry);
377	}
378	return count;
379
380out:
381	kfree(new_entry);
382	return err;
383}
384
385static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
386			     struct bin_attribute *bin_attr,
387			     char *buf, loff_t pos, size_t count)
388{
389	struct efi_variable *del_var = (struct efi_variable *)buf;
390	struct efivar_entry *entry;
391	efi_char16_t *name;
392	efi_guid_t vendor;
393	int err = 0;
394
395	if (!capable(CAP_SYS_ADMIN))
396		return -EACCES;
397
398	name = del_var->VariableName;
399	vendor = del_var->VendorGuid;
400
401	efivar_entry_iter_begin();
402	entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
403	if (!entry)
404		err = -EINVAL;
405	else if (__efivar_entry_delete(entry))
406		err = -EIO;
407
408	if (err) {
409		efivar_entry_iter_end();
410		return err;
411	}
412
413	if (!entry->scanning) {
414		efivar_entry_iter_end();
415		efivar_unregister(entry);
416	} else
417		efivar_entry_iter_end();
418
419	/* It's dead Jim.... */
420	return count;
421}
422
423/**
424 * efivar_create_sysfs_entry - create a new entry in sysfs
425 * @new_var: efivar entry to create
426 *
427 * Returns 1 on failure, 0 on success
428 */
429static int
430efivar_create_sysfs_entry(struct efivar_entry *new_var)
431{
432	int i, short_name_size;
433	char *short_name;
434	unsigned long variable_name_size;
435	efi_char16_t *variable_name;
436
437	variable_name = new_var->var.VariableName;
438	variable_name_size = ucs2_strlen(variable_name) * sizeof(efi_char16_t);
439
440	/*
441	 * Length of the variable bytes in ASCII, plus the '-' separator,
442	 * plus the GUID, plus trailing NUL
443	 */
444	short_name_size = variable_name_size / sizeof(efi_char16_t)
445				+ 1 + EFI_VARIABLE_GUID_LEN + 1;
446
447	short_name = kzalloc(short_name_size, GFP_KERNEL);
448
449	if (!short_name)
450		return 1;
451
452	/* Convert Unicode to normal chars (assume top bits are 0),
453	   ala UTF-8 */
454	for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
455		short_name[i] = variable_name[i] & 0xFF;
456	}
457	/* This is ugly, but necessary to separate one vendor's
458	   private variables from another's.         */
459
460	*(short_name + strlen(short_name)) = '-';
461	efi_guid_unparse(&new_var->var.VendorGuid,
462			 short_name + strlen(short_name));
463
464	new_var->kobj.kset = efivars_kset;
465
466	i = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
467				   NULL, "%s", short_name);
468	kfree(short_name);
469	if (i)
470		return 1;
471
472	kobject_uevent(&new_var->kobj, KOBJ_ADD);
473	efivar_entry_add(new_var, &efivar_sysfs_list);
474
475	return 0;
476}
477
478static int
479create_efivars_bin_attributes(void)
480{
481	struct bin_attribute *attr;
482	int error;
483
484	/* new_var */
485	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
486	if (!attr)
487		return -ENOMEM;
488
489	attr->attr.name = "new_var";
490	attr->attr.mode = 0200;
491	attr->write = efivar_create;
492	efivars_new_var = attr;
493
494	/* del_var */
495	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
496	if (!attr) {
497		error = -ENOMEM;
498		goto out_free;
499	}
500	attr->attr.name = "del_var";
501	attr->attr.mode = 0200;
502	attr->write = efivar_delete;
503	efivars_del_var = attr;
504
505	sysfs_bin_attr_init(efivars_new_var);
506	sysfs_bin_attr_init(efivars_del_var);
507
508	/* Register */
509	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
510	if (error) {
511		printk(KERN_ERR "efivars: unable to create new_var sysfs file"
512			" due to error %d\n", error);
513		goto out_free;
514	}
515
516	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
517	if (error) {
518		printk(KERN_ERR "efivars: unable to create del_var sysfs file"
519			" due to error %d\n", error);
520		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
521		goto out_free;
522	}
523
524	return 0;
525out_free:
526	kfree(efivars_del_var);
527	efivars_del_var = NULL;
528	kfree(efivars_new_var);
529	efivars_new_var = NULL;
530	return error;
531}
532
533static int efivar_update_sysfs_entry(efi_char16_t *name, efi_guid_t vendor,
534				     unsigned long name_size, void *data)
535{
536	struct efivar_entry *entry = data;
537
538	if (efivar_entry_find(name, vendor, &efivar_sysfs_list, false))
539		return 0;
540
541	memcpy(entry->var.VariableName, name, name_size);
542	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
543
544	return 1;
545}
546
547static void efivar_update_sysfs_entries(struct work_struct *work)
548{
549	struct efivar_entry *entry;
550	int err;
551
552	/* Add new sysfs entries */
553	while (1) {
554		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
555		if (!entry)
556			return;
557
558		err = efivar_init(efivar_update_sysfs_entry, entry,
559				  true, false, &efivar_sysfs_list);
560		if (!err)
561			break;
562
563		efivar_create_sysfs_entry(entry);
564	}
565
566	kfree(entry);
567}
568
569static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
570				  unsigned long name_size, void *data)
571{
572	struct efivar_entry *entry;
573
574	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
575	if (!entry)
576		return -ENOMEM;
577
578	memcpy(entry->var.VariableName, name, name_size);
579	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
580
581	efivar_create_sysfs_entry(entry);
582
583	return 0;
584}
585
586static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
587{
588	efivar_entry_remove(entry);
589	efivar_unregister(entry);
590	return 0;
591}
592
593static void efivars_sysfs_exit(void)
594{
595	/* Remove all entries and destroy */
596	__efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list, NULL, NULL);
597
598	if (efivars_new_var)
599		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
600	if (efivars_del_var)
601		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
602	kfree(efivars_new_var);
603	kfree(efivars_del_var);
604	kset_unregister(efivars_kset);
605}
606
607int efivars_sysfs_init(void)
608{
609	struct kobject *parent_kobj = efivars_kobject();
610	int error = 0;
611
612	if (!efi_enabled(EFI_RUNTIME_SERVICES))
613		return -ENODEV;
614
615	/* No efivars has been registered yet */
616	if (!parent_kobj)
617		return 0;
618
619	printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
620	       EFIVARS_DATE);
621
622	efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
623	if (!efivars_kset) {
624		printk(KERN_ERR "efivars: Subsystem registration failed.\n");
625		return -ENOMEM;
626	}
627
628	efivar_init(efivars_sysfs_callback, NULL, false,
629		    true, &efivar_sysfs_list);
630
631	error = create_efivars_bin_attributes();
632	if (error) {
633		efivars_sysfs_exit();
634		return error;
635	}
636
637	INIT_WORK(&efivar_work, efivar_update_sysfs_entries);
638
639	return 0;
640}
641EXPORT_SYMBOL_GPL(efivars_sysfs_init);
642
643module_init(efivars_sysfs_init);
644module_exit(efivars_sysfs_exit);
645