1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2012 Red Hat, Inc.
7 #include <linux/ctype.h>
10 #include <linux/fs_context.h>
11 #include <linux/fs_parser.h>
12 #include <linux/module.h>
13 #include <linux/pagemap.h>
14 #include <linux/ucs2_string.h>
15 #include <linux/slab.h>
16 #include <linux/magic.h>
17 #include <linux/statfs.h>
18 #include <linux/notifier.h>
19 #include <linux/printk.h>
23 static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event,
26 struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb);
29 case EFIVAR_OPS_RDONLY:
30 sfi->sb->s_flags |= SB_RDONLY;
33 sfi->sb->s_flags &= ~SB_RDONLY;
42 static void efivarfs_evict_inode(struct inode *inode)
47 static int efivarfs_show_options(struct seq_file *m, struct dentry *root)
49 struct super_block *sb = root->d_sb;
50 struct efivarfs_fs_info *sbi = sb->s_fs_info;
51 struct efivarfs_mount_opts *opts = &sbi->mount_opts;
53 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
54 seq_printf(m, ",uid=%u",
55 from_kuid_munged(&init_user_ns, opts->uid));
56 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
57 seq_printf(m, ",gid=%u",
58 from_kgid_munged(&init_user_ns, opts->gid));
62 static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)
64 const u32 attr = EFI_VARIABLE_NON_VOLATILE |
65 EFI_VARIABLE_BOOTSERVICE_ACCESS |
66 EFI_VARIABLE_RUNTIME_ACCESS;
67 u64 storage_space, remaining_space, max_variable_size;
68 u64 id = huge_encode_dev(dentry->d_sb->s_dev);
71 /* Some UEFI firmware does not implement QueryVariableInfo() */
72 storage_space = remaining_space = 0;
73 if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) {
74 status = efivar_query_variable_info(attr, &storage_space,
77 if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)
78 pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n",
83 * This is not a normal filesystem, so no point in pretending it has a block
84 * size; we declare f_bsize to 1, so that we can then report the exact value
85 * sent by EFI QueryVariableInfo in f_blocks and f_bfree
88 buf->f_namelen = NAME_MAX;
89 buf->f_blocks = storage_space;
90 buf->f_bfree = remaining_space;
91 buf->f_type = dentry->d_sb->s_magic;
92 buf->f_fsid = u64_to_fsid(id);
95 * In f_bavail we declare the free space that the kernel will allow writing
96 * when the storage_paranoia x86 quirk is active. To use more, users
97 * should boot the kernel with efi_no_storage_paranoia.
99 if (remaining_space > efivar_reserved_space())
100 buf->f_bavail = remaining_space - efivar_reserved_space();
106 static const struct super_operations efivarfs_ops = {
107 .statfs = efivarfs_statfs,
108 .drop_inode = generic_delete_inode,
109 .evict_inode = efivarfs_evict_inode,
110 .show_options = efivarfs_show_options,
114 * Compare two efivarfs file names.
116 * An efivarfs filename is composed of two parts,
118 * 1. A case-sensitive variable name
119 * 2. A case-insensitive GUID
121 * So we need to perform a case-sensitive match on part 1 and a
122 * case-insensitive match on part 2.
124 static int efivarfs_d_compare(const struct dentry *dentry,
125 unsigned int len, const char *str,
126 const struct qstr *name)
128 int guid = len - EFI_VARIABLE_GUID_LEN;
130 if (name->len != len)
133 /* Case-sensitive compare for the variable name */
134 if (memcmp(str, name->name, guid))
137 /* Case-insensitive compare for the GUID */
138 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
141 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
143 unsigned long hash = init_name_hash(dentry);
144 const unsigned char *s = qstr->name;
145 unsigned int len = qstr->len;
147 if (!efivarfs_valid_name(s, len))
150 while (len-- > EFI_VARIABLE_GUID_LEN)
151 hash = partial_name_hash(*s++, hash);
153 /* GUID is case-insensitive. */
155 hash = partial_name_hash(tolower(*s++), hash);
157 qstr->hash = end_name_hash(hash);
161 static const struct dentry_operations efivarfs_d_ops = {
162 .d_compare = efivarfs_d_compare,
163 .d_hash = efivarfs_d_hash,
164 .d_delete = always_delete_dentry,
167 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
174 q.len = strlen(name);
176 err = efivarfs_d_hash(parent, &q);
180 d = d_alloc(parent, &q);
184 return ERR_PTR(-ENOMEM);
187 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
188 unsigned long name_size, void *data,
189 struct list_head *list)
191 struct super_block *sb = (struct super_block *)data;
192 struct efivar_entry *entry;
193 struct inode *inode = NULL;
194 struct dentry *dentry, *root = sb->s_root;
195 unsigned long size = 0;
199 bool is_removable = false;
201 if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
204 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
208 memcpy(entry->var.VariableName, name16, name_size);
209 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
211 len = ucs2_utf8size(entry->var.VariableName);
213 /* name, plus '-', plus GUID, plus NUL*/
214 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
218 ucs2_as_utf8(name, entry->var.VariableName, len);
220 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
225 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
227 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
229 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
230 strreplace(name, '/', '!');
232 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
237 dentry = efivarfs_alloc_dentry(root, name);
238 if (IS_ERR(dentry)) {
239 err = PTR_ERR(dentry);
243 __efivar_entry_get(entry, NULL, &size, NULL);
244 __efivar_entry_add(entry, list);
246 /* copied by the above to local storage in the dentry. */
250 inode->i_private = entry;
251 i_size_write(inode, size + sizeof(entry->var.Attributes));
253 d_add(dentry, inode);
266 static int efivarfs_destroy(struct efivar_entry *entry, void *data)
268 efivar_entry_remove(entry);
277 static const struct fs_parameter_spec efivarfs_parameters[] = {
278 fsparam_u32("uid", Opt_uid),
279 fsparam_u32("gid", Opt_gid),
283 static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
285 struct efivarfs_fs_info *sbi = fc->s_fs_info;
286 struct efivarfs_mount_opts *opts = &sbi->mount_opts;
287 struct fs_parse_result result;
290 opt = fs_parse(fc, efivarfs_parameters, param, &result);
296 opts->uid = make_kuid(current_user_ns(), result.uint_32);
297 if (!uid_valid(opts->uid))
301 opts->gid = make_kgid(current_user_ns(), result.uint_32);
302 if (!gid_valid(opts->gid))
312 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
314 struct efivarfs_fs_info *sfi = sb->s_fs_info;
315 struct inode *inode = NULL;
319 sb->s_maxbytes = MAX_LFS_FILESIZE;
320 sb->s_blocksize = PAGE_SIZE;
321 sb->s_blocksize_bits = PAGE_SHIFT;
322 sb->s_magic = EFIVARFS_MAGIC;
323 sb->s_op = &efivarfs_ops;
324 sb->s_d_op = &efivarfs_d_ops;
327 if (!efivar_supports_writes())
328 sb->s_flags |= SB_RDONLY;
330 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
333 inode->i_op = &efivarfs_dir_inode_operations;
335 root = d_make_root(inode);
341 sfi->nb.notifier_call = efivarfs_ops_notifier;
342 err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb);
346 return efivar_init(efivarfs_callback, sb, &sfi->efivarfs_list);
349 static int efivarfs_get_tree(struct fs_context *fc)
351 return get_tree_single(fc, efivarfs_fill_super);
354 static int efivarfs_reconfigure(struct fs_context *fc)
356 if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) {
357 pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n");
364 static const struct fs_context_operations efivarfs_context_ops = {
365 .get_tree = efivarfs_get_tree,
366 .parse_param = efivarfs_parse_param,
367 .reconfigure = efivarfs_reconfigure,
370 static int efivarfs_init_fs_context(struct fs_context *fc)
372 struct efivarfs_fs_info *sfi;
374 if (!efivar_is_available())
377 sfi = kzalloc(sizeof(*sfi), GFP_KERNEL);
381 INIT_LIST_HEAD(&sfi->efivarfs_list);
383 sfi->mount_opts.uid = GLOBAL_ROOT_UID;
384 sfi->mount_opts.gid = GLOBAL_ROOT_GID;
387 fc->ops = &efivarfs_context_ops;
391 static void efivarfs_kill_sb(struct super_block *sb)
393 struct efivarfs_fs_info *sfi = sb->s_fs_info;
395 blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);
396 kill_litter_super(sb);
398 /* Remove all entries and destroy */
399 efivar_entry_iter(efivarfs_destroy, &sfi->efivarfs_list, NULL);
403 static struct file_system_type efivarfs_type = {
404 .owner = THIS_MODULE,
406 .init_fs_context = efivarfs_init_fs_context,
407 .kill_sb = efivarfs_kill_sb,
408 .parameters = efivarfs_parameters,
411 static __init int efivarfs_init(void)
413 return register_filesystem(&efivarfs_type);
416 static __exit void efivarfs_exit(void)
418 unregister_filesystem(&efivarfs_type);
421 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
422 MODULE_DESCRIPTION("EFI Variable Filesystem");
423 MODULE_LICENSE("GPL");
424 MODULE_ALIAS_FS("efivarfs");
426 module_init(efivarfs_init);
427 module_exit(efivarfs_exit);