Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat, Inc.
4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
5 */
6
7#include <linux/ctype.h>
8#include <linux/efi.h>
9#include <linux/fs.h>
10#include <linux/fs_context.h>
11#include <linux/module.h>
12#include <linux/pagemap.h>
13#include <linux/ucs2_string.h>
14#include <linux/slab.h>
15#include <linux/magic.h>
16
17#include "internal.h"
18
19LIST_HEAD(efivarfs_list);
20
21static void efivarfs_evict_inode(struct inode *inode)
22{
23 clear_inode(inode);
24}
25
26static const struct super_operations efivarfs_ops = {
27 .statfs = simple_statfs,
28 .drop_inode = generic_delete_inode,
29 .evict_inode = efivarfs_evict_inode,
30};
31
32/*
33 * Compare two efivarfs file names.
34 *
35 * An efivarfs filename is composed of two parts,
36 *
37 * 1. A case-sensitive variable name
38 * 2. A case-insensitive GUID
39 *
40 * So we need to perform a case-sensitive match on part 1 and a
41 * case-insensitive match on part 2.
42 */
43static int efivarfs_d_compare(const struct dentry *dentry,
44 unsigned int len, const char *str,
45 const struct qstr *name)
46{
47 int guid = len - EFI_VARIABLE_GUID_LEN;
48
49 if (name->len != len)
50 return 1;
51
52 /* Case-sensitive compare for the variable name */
53 if (memcmp(str, name->name, guid))
54 return 1;
55
56 /* Case-insensitive compare for the GUID */
57 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
58}
59
60static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
61{
62 unsigned long hash = init_name_hash(dentry);
63 const unsigned char *s = qstr->name;
64 unsigned int len = qstr->len;
65
66 if (!efivarfs_valid_name(s, len))
67 return -EINVAL;
68
69 while (len-- > EFI_VARIABLE_GUID_LEN)
70 hash = partial_name_hash(*s++, hash);
71
72 /* GUID is case-insensitive. */
73 while (len--)
74 hash = partial_name_hash(tolower(*s++), hash);
75
76 qstr->hash = end_name_hash(hash);
77 return 0;
78}
79
80static const struct dentry_operations efivarfs_d_ops = {
81 .d_compare = efivarfs_d_compare,
82 .d_hash = efivarfs_d_hash,
83 .d_delete = always_delete_dentry,
84};
85
86static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
87{
88 struct dentry *d;
89 struct qstr q;
90 int err;
91
92 q.name = name;
93 q.len = strlen(name);
94
95 err = efivarfs_d_hash(parent, &q);
96 if (err)
97 return ERR_PTR(err);
98
99 d = d_alloc(parent, &q);
100 if (d)
101 return d;
102
103 return ERR_PTR(-ENOMEM);
104}
105
106static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
107 unsigned long name_size, void *data)
108{
109 struct super_block *sb = (struct super_block *)data;
110 struct efivar_entry *entry;
111 struct inode *inode = NULL;
112 struct dentry *dentry, *root = sb->s_root;
113 unsigned long size = 0;
114 char *name;
115 int len;
116 int err = -ENOMEM;
117 bool is_removable = false;
118
119 if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
120 return 0;
121
122 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
123 if (!entry)
124 return err;
125
126 memcpy(entry->var.VariableName, name16, name_size);
127 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
128
129 len = ucs2_utf8size(entry->var.VariableName);
130
131 /* name, plus '-', plus GUID, plus NUL*/
132 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
133 if (!name)
134 goto fail;
135
136 ucs2_as_utf8(name, entry->var.VariableName, len);
137
138 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
139 is_removable = true;
140
141 name[len] = '-';
142
143 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
144
145 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
146
147 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
148 strreplace(name, '/', '!');
149
150 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
151 is_removable);
152 if (!inode)
153 goto fail_name;
154
155 dentry = efivarfs_alloc_dentry(root, name);
156 if (IS_ERR(dentry)) {
157 err = PTR_ERR(dentry);
158 goto fail_inode;
159 }
160
161 __efivar_entry_get(entry, NULL, &size, NULL);
162 __efivar_entry_add(entry, &efivarfs_list);
163
164 /* copied by the above to local storage in the dentry. */
165 kfree(name);
166
167 inode_lock(inode);
168 inode->i_private = entry;
169 i_size_write(inode, size + sizeof(entry->var.Attributes));
170 inode_unlock(inode);
171 d_add(dentry, inode);
172
173 return 0;
174
175fail_inode:
176 iput(inode);
177fail_name:
178 kfree(name);
179fail:
180 kfree(entry);
181 return err;
182}
183
184static int efivarfs_destroy(struct efivar_entry *entry, void *data)
185{
186 efivar_entry_remove(entry);
187 kfree(entry);
188 return 0;
189}
190
191static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
192{
193 struct inode *inode = NULL;
194 struct dentry *root;
195 int err;
196
197 sb->s_maxbytes = MAX_LFS_FILESIZE;
198 sb->s_blocksize = PAGE_SIZE;
199 sb->s_blocksize_bits = PAGE_SHIFT;
200 sb->s_magic = EFIVARFS_MAGIC;
201 sb->s_op = &efivarfs_ops;
202 sb->s_d_op = &efivarfs_d_ops;
203 sb->s_time_gran = 1;
204
205 if (!efivar_supports_writes())
206 sb->s_flags |= SB_RDONLY;
207
208 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
209 if (!inode)
210 return -ENOMEM;
211 inode->i_op = &efivarfs_dir_inode_operations;
212
213 root = d_make_root(inode);
214 sb->s_root = root;
215 if (!root)
216 return -ENOMEM;
217
218 INIT_LIST_HEAD(&efivarfs_list);
219
220 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
221 if (err)
222 efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL);
223
224 return err;
225}
226
227static int efivarfs_get_tree(struct fs_context *fc)
228{
229 return get_tree_single(fc, efivarfs_fill_super);
230}
231
232static const struct fs_context_operations efivarfs_context_ops = {
233 .get_tree = efivarfs_get_tree,
234};
235
236static int efivarfs_init_fs_context(struct fs_context *fc)
237{
238 fc->ops = &efivarfs_context_ops;
239 return 0;
240}
241
242static void efivarfs_kill_sb(struct super_block *sb)
243{
244 kill_litter_super(sb);
245
246 /* Remove all entries and destroy */
247 efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL);
248}
249
250static struct file_system_type efivarfs_type = {
251 .owner = THIS_MODULE,
252 .name = "efivarfs",
253 .init_fs_context = efivarfs_init_fs_context,
254 .kill_sb = efivarfs_kill_sb,
255};
256
257static __init int efivarfs_init(void)
258{
259 if (!efivars_kobject())
260 return -ENODEV;
261
262 return register_filesystem(&efivarfs_type);
263}
264
265static __exit void efivarfs_exit(void)
266{
267 unregister_filesystem(&efivarfs_type);
268}
269
270MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
271MODULE_DESCRIPTION("EFI Variable Filesystem");
272MODULE_LICENSE("GPL");
273MODULE_ALIAS_FS("efivarfs");
274
275module_init(efivarfs_init);
276module_exit(efivarfs_exit);