1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2012 Red Hat, Inc.
4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
7 #include <linux/ctype.h>
10 #include <linux/module.h>
11 #include <linux/pagemap.h>
12 #include <linux/ucs2_string.h>
13 #include <linux/slab.h>
14 #include <linux/magic.h>
18 LIST_HEAD(efivarfs_list);
20 static void efivarfs_evict_inode(struct inode *inode)
25 static const struct super_operations efivarfs_ops = {
26 .statfs = simple_statfs,
27 .drop_inode = generic_delete_inode,
28 .evict_inode = efivarfs_evict_inode,
31 static struct super_block *efivarfs_sb;
34 * Compare two efivarfs file names.
36 * An efivarfs filename is composed of two parts,
38 * 1. A case-sensitive variable name
39 * 2. A case-insensitive GUID
41 * So we need to perform a case-sensitive match on part 1 and a
42 * case-insensitive match on part 2.
44 static int efivarfs_d_compare(const struct dentry *dentry,
45 unsigned int len, const char *str,
46 const struct qstr *name)
48 int guid = len - EFI_VARIABLE_GUID_LEN;
53 /* Case-sensitive compare for the variable name */
54 if (memcmp(str, name->name, guid))
57 /* Case-insensitive compare for the GUID */
58 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
61 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
63 unsigned long hash = init_name_hash(dentry);
64 const unsigned char *s = qstr->name;
65 unsigned int len = qstr->len;
67 if (!efivarfs_valid_name(s, len))
70 while (len-- > EFI_VARIABLE_GUID_LEN)
71 hash = partial_name_hash(*s++, hash);
73 /* GUID is case-insensitive. */
75 hash = partial_name_hash(tolower(*s++), hash);
77 qstr->hash = end_name_hash(hash);
81 static const struct dentry_operations efivarfs_d_ops = {
82 .d_compare = efivarfs_d_compare,
83 .d_hash = efivarfs_d_hash,
84 .d_delete = always_delete_dentry,
87 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
96 err = efivarfs_d_hash(parent, &q);
100 d = d_alloc(parent, &q);
104 return ERR_PTR(-ENOMEM);
107 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
108 unsigned long name_size, void *data)
110 struct super_block *sb = (struct super_block *)data;
111 struct efivar_entry *entry;
112 struct inode *inode = NULL;
113 struct dentry *dentry, *root = sb->s_root;
114 unsigned long size = 0;
118 bool is_removable = false;
120 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
124 memcpy(entry->var.VariableName, name16, name_size);
125 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
127 len = ucs2_utf8size(entry->var.VariableName);
129 /* name, plus '-', plus GUID, plus NUL*/
130 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
134 ucs2_as_utf8(name, entry->var.VariableName, len);
136 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
141 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
143 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
145 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
150 dentry = efivarfs_alloc_dentry(root, name);
151 if (IS_ERR(dentry)) {
152 err = PTR_ERR(dentry);
156 efivar_entry_size(entry, &size);
157 err = efivar_entry_add(entry, &efivarfs_list);
161 /* copied by the above to local storage in the dentry. */
165 inode->i_private = entry;
166 i_size_write(inode, size + sizeof(entry->var.Attributes));
168 d_add(dentry, inode);
181 static int efivarfs_destroy(struct efivar_entry *entry, void *data)
183 int err = efivar_entry_remove(entry);
191 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
193 struct inode *inode = NULL;
199 sb->s_maxbytes = MAX_LFS_FILESIZE;
200 sb->s_blocksize = PAGE_SIZE;
201 sb->s_blocksize_bits = PAGE_SHIFT;
202 sb->s_magic = EFIVARFS_MAGIC;
203 sb->s_op = &efivarfs_ops;
204 sb->s_d_op = &efivarfs_d_ops;
207 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
210 inode->i_op = &efivarfs_dir_inode_operations;
212 root = d_make_root(inode);
217 INIT_LIST_HEAD(&efivarfs_list);
219 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
221 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
226 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
227 int flags, const char *dev_name, void *data)
229 return mount_single(fs_type, flags, data, efivarfs_fill_super);
232 static void efivarfs_kill_sb(struct super_block *sb)
234 kill_litter_super(sb);
237 /* Remove all entries and destroy */
238 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
241 static struct file_system_type efivarfs_type = {
242 .owner = THIS_MODULE,
244 .mount = efivarfs_mount,
245 .kill_sb = efivarfs_kill_sb,
248 static __init int efivarfs_init(void)
250 if (!efi_enabled(EFI_RUNTIME_SERVICES))
253 if (!efivars_kobject())
256 return register_filesystem(&efivarfs_type);
259 static __exit void efivarfs_exit(void)
261 unregister_filesystem(&efivarfs_type);
264 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
265 MODULE_DESCRIPTION("EFI Variable Filesystem");
266 MODULE_LICENSE("GPL");
267 MODULE_ALIAS_FS("efivarfs");
269 module_init(efivarfs_init);
270 module_exit(efivarfs_exit);