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/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>
19 LIST_HEAD(efivarfs_list);
21 static void efivarfs_evict_inode(struct inode *inode)
26 static const struct super_operations efivarfs_ops = {
27 .statfs = simple_statfs,
28 .drop_inode = generic_delete_inode,
29 .evict_inode = efivarfs_evict_inode,
33 * Compare two efivarfs file names.
35 * An efivarfs filename is composed of two parts,
37 * 1. A case-sensitive variable name
38 * 2. A case-insensitive GUID
40 * So we need to perform a case-sensitive match on part 1 and a
41 * case-insensitive match on part 2.
43 static int efivarfs_d_compare(const struct dentry *dentry,
44 unsigned int len, const char *str,
45 const struct qstr *name)
47 int guid = len - EFI_VARIABLE_GUID_LEN;
52 /* Case-sensitive compare for the variable name */
53 if (memcmp(str, name->name, guid))
56 /* Case-insensitive compare for the GUID */
57 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
60 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
62 unsigned long hash = init_name_hash(dentry);
63 const unsigned char *s = qstr->name;
64 unsigned int len = qstr->len;
66 if (!efivarfs_valid_name(s, len))
69 while (len-- > EFI_VARIABLE_GUID_LEN)
70 hash = partial_name_hash(*s++, hash);
72 /* GUID is case-insensitive. */
74 hash = partial_name_hash(tolower(*s++), hash);
76 qstr->hash = end_name_hash(hash);
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,
86 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
95 err = efivarfs_d_hash(parent, &q);
99 d = d_alloc(parent, &q);
103 return ERR_PTR(-ENOMEM);
106 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
107 unsigned long name_size, void *data)
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;
117 bool is_removable = false;
119 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
123 memcpy(entry->var.VariableName, name16, name_size);
124 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
126 len = ucs2_utf8size(entry->var.VariableName);
128 /* name, plus '-', plus GUID, plus NUL*/
129 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
133 ucs2_as_utf8(name, entry->var.VariableName, len);
135 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
140 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
142 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
144 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
145 strreplace(name, '/', '!');
147 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
152 dentry = efivarfs_alloc_dentry(root, name);
153 if (IS_ERR(dentry)) {
154 err = PTR_ERR(dentry);
158 efivar_entry_size(entry, &size);
159 err = efivar_entry_add(entry, &efivarfs_list);
163 /* copied by the above to local storage in the dentry. */
167 inode->i_private = entry;
168 i_size_write(inode, size + sizeof(entry->var.Attributes));
170 d_add(dentry, inode);
183 static int efivarfs_destroy(struct efivar_entry *entry, void *data)
185 int err = efivar_entry_remove(entry);
193 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
195 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 if (!efivar_supports_writes())
208 sb->s_flags |= SB_RDONLY;
210 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
213 inode->i_op = &efivarfs_dir_inode_operations;
215 root = d_make_root(inode);
220 INIT_LIST_HEAD(&efivarfs_list);
222 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
224 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
229 static int efivarfs_get_tree(struct fs_context *fc)
231 return get_tree_single(fc, efivarfs_fill_super);
234 static const struct fs_context_operations efivarfs_context_ops = {
235 .get_tree = efivarfs_get_tree,
238 static int efivarfs_init_fs_context(struct fs_context *fc)
240 fc->ops = &efivarfs_context_ops;
244 static void efivarfs_kill_sb(struct super_block *sb)
246 kill_litter_super(sb);
248 /* Remove all entries and destroy */
249 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
252 static struct file_system_type efivarfs_type = {
253 .owner = THIS_MODULE,
255 .init_fs_context = efivarfs_init_fs_context,
256 .kill_sb = efivarfs_kill_sb,
259 static __init int efivarfs_init(void)
261 if (!efivars_kobject())
264 return register_filesystem(&efivarfs_type);
267 static __exit void efivarfs_exit(void)
269 unregister_filesystem(&efivarfs_type);
272 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
273 MODULE_DESCRIPTION("EFI Variable Filesystem");
274 MODULE_LICENSE("GPL");
275 MODULE_ALIAS_FS("efivarfs");
277 module_init(efivarfs_init);
278 module_exit(efivarfs_exit);