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
19 LIST_HEAD(efivarfs_list);
20
efivarfs_evict_inode(struct inode * inode)21 static void efivarfs_evict_inode(struct inode *inode)
22 {
23 clear_inode(inode);
24 }
25
26 static 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 */
efivarfs_d_compare(const struct dentry * dentry,unsigned int len,const char * str,const struct qstr * name)43 static 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
efivarfs_d_hash(const struct dentry * dentry,struct qstr * qstr)60 static 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
80 static 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
efivarfs_alloc_dentry(struct dentry * parent,char * name)86 static 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
efivarfs_callback(efi_char16_t * name16,efi_guid_t vendor,unsigned long name_size,void * data)106 static 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 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
120 if (!entry)
121 return err;
122
123 memcpy(entry->var.VariableName, name16, name_size);
124 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
125
126 len = ucs2_utf8size(entry->var.VariableName);
127
128 /* name, plus '-', plus GUID, plus NUL*/
129 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
130 if (!name)
131 goto fail;
132
133 ucs2_as_utf8(name, entry->var.VariableName, len);
134
135 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
136 is_removable = true;
137
138 name[len] = '-';
139
140 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
141
142 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
143
144 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
145 is_removable);
146 if (!inode)
147 goto fail_name;
148
149 dentry = efivarfs_alloc_dentry(root, name);
150 if (IS_ERR(dentry)) {
151 err = PTR_ERR(dentry);
152 goto fail_inode;
153 }
154
155 efivar_entry_size(entry, &size);
156 err = efivar_entry_add(entry, &efivarfs_list);
157 if (err)
158 goto fail_inode;
159
160 /* copied by the above to local storage in the dentry. */
161 kfree(name);
162
163 inode_lock(inode);
164 inode->i_private = entry;
165 i_size_write(inode, size + sizeof(entry->var.Attributes));
166 inode_unlock(inode);
167 d_add(dentry, inode);
168
169 return 0;
170
171 fail_inode:
172 iput(inode);
173 fail_name:
174 kfree(name);
175 fail:
176 kfree(entry);
177 return err;
178 }
179
efivarfs_destroy(struct efivar_entry * entry,void * data)180 static int efivarfs_destroy(struct efivar_entry *entry, void *data)
181 {
182 int err = efivar_entry_remove(entry);
183
184 if (err)
185 return err;
186 kfree(entry);
187 return 0;
188 }
189
efivarfs_fill_super(struct super_block * sb,struct fs_context * fc)190 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
191 {
192 struct inode *inode = NULL;
193 struct dentry *root;
194 int err;
195
196 sb->s_maxbytes = MAX_LFS_FILESIZE;
197 sb->s_blocksize = PAGE_SIZE;
198 sb->s_blocksize_bits = PAGE_SHIFT;
199 sb->s_magic = EFIVARFS_MAGIC;
200 sb->s_op = &efivarfs_ops;
201 sb->s_d_op = &efivarfs_d_ops;
202 sb->s_time_gran = 1;
203
204 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
205 if (!inode)
206 return -ENOMEM;
207 inode->i_op = &efivarfs_dir_inode_operations;
208
209 root = d_make_root(inode);
210 sb->s_root = root;
211 if (!root)
212 return -ENOMEM;
213
214 INIT_LIST_HEAD(&efivarfs_list);
215
216 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
217 if (err)
218 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
219
220 return err;
221 }
222
efivarfs_get_tree(struct fs_context * fc)223 static int efivarfs_get_tree(struct fs_context *fc)
224 {
225 return get_tree_single(fc, efivarfs_fill_super);
226 }
227
228 static const struct fs_context_operations efivarfs_context_ops = {
229 .get_tree = efivarfs_get_tree,
230 };
231
efivarfs_init_fs_context(struct fs_context * fc)232 static int efivarfs_init_fs_context(struct fs_context *fc)
233 {
234 fc->ops = &efivarfs_context_ops;
235 return 0;
236 }
237
efivarfs_kill_sb(struct super_block * sb)238 static void efivarfs_kill_sb(struct super_block *sb)
239 {
240 kill_litter_super(sb);
241
242 /* Remove all entries and destroy */
243 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
244 }
245
246 static struct file_system_type efivarfs_type = {
247 .owner = THIS_MODULE,
248 .name = "efivarfs",
249 .init_fs_context = efivarfs_init_fs_context,
250 .kill_sb = efivarfs_kill_sb,
251 };
252
efivarfs_init(void)253 static __init int efivarfs_init(void)
254 {
255 if (!efi_enabled(EFI_RUNTIME_SERVICES))
256 return -ENODEV;
257
258 if (!efivars_kobject())
259 return -ENODEV;
260
261 return register_filesystem(&efivarfs_type);
262 }
263
efivarfs_exit(void)264 static __exit void efivarfs_exit(void)
265 {
266 unregister_filesystem(&efivarfs_type);
267 }
268
269 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
270 MODULE_DESCRIPTION("EFI Variable Filesystem");
271 MODULE_LICENSE("GPL");
272 MODULE_ALIAS_FS("efivarfs");
273
274 module_init(efivarfs_init);
275 module_exit(efivarfs_exit);
276