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 #include <linux/statfs.h> 17 18 #include "internal.h" 19 20 LIST_HEAD(efivarfs_list); 21 22 static void efivarfs_evict_inode(struct inode *inode) 23 { 24 clear_inode(inode); 25 } 26 27 static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) 28 { 29 const u32 attr = EFI_VARIABLE_NON_VOLATILE | 30 EFI_VARIABLE_BOOTSERVICE_ACCESS | 31 EFI_VARIABLE_RUNTIME_ACCESS; 32 u64 storage_space, remaining_space, max_variable_size; 33 efi_status_t status; 34 35 status = efivar_query_variable_info(attr, &storage_space, &remaining_space, 36 &max_variable_size); 37 if (status != EFI_SUCCESS) 38 return efi_status_to_err(status); 39 40 /* 41 * This is not a normal filesystem, so no point in pretending it has a block 42 * size; we declare f_bsize to 1, so that we can then report the exact value 43 * sent by EFI QueryVariableInfo in f_blocks and f_bfree 44 */ 45 buf->f_bsize = 1; 46 buf->f_namelen = NAME_MAX; 47 buf->f_blocks = storage_space; 48 buf->f_bfree = remaining_space; 49 buf->f_type = dentry->d_sb->s_magic; 50 51 /* 52 * In f_bavail we declare the free space that the kernel will allow writing 53 * when the storage_paranoia x86 quirk is active. To use more, users 54 * should boot the kernel with efi_no_storage_paranoia. 55 */ 56 if (remaining_space > efivar_reserved_space()) 57 buf->f_bavail = remaining_space - efivar_reserved_space(); 58 else 59 buf->f_bavail = 0; 60 61 return 0; 62 } 63 static const struct super_operations efivarfs_ops = { 64 .statfs = efivarfs_statfs, 65 .drop_inode = generic_delete_inode, 66 .evict_inode = efivarfs_evict_inode, 67 }; 68 69 /* 70 * Compare two efivarfs file names. 71 * 72 * An efivarfs filename is composed of two parts, 73 * 74 * 1. A case-sensitive variable name 75 * 2. A case-insensitive GUID 76 * 77 * So we need to perform a case-sensitive match on part 1 and a 78 * case-insensitive match on part 2. 79 */ 80 static int efivarfs_d_compare(const struct dentry *dentry, 81 unsigned int len, const char *str, 82 const struct qstr *name) 83 { 84 int guid = len - EFI_VARIABLE_GUID_LEN; 85 86 if (name->len != len) 87 return 1; 88 89 /* Case-sensitive compare for the variable name */ 90 if (memcmp(str, name->name, guid)) 91 return 1; 92 93 /* Case-insensitive compare for the GUID */ 94 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); 95 } 96 97 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) 98 { 99 unsigned long hash = init_name_hash(dentry); 100 const unsigned char *s = qstr->name; 101 unsigned int len = qstr->len; 102 103 if (!efivarfs_valid_name(s, len)) 104 return -EINVAL; 105 106 while (len-- > EFI_VARIABLE_GUID_LEN) 107 hash = partial_name_hash(*s++, hash); 108 109 /* GUID is case-insensitive. */ 110 while (len--) 111 hash = partial_name_hash(tolower(*s++), hash); 112 113 qstr->hash = end_name_hash(hash); 114 return 0; 115 } 116 117 static const struct dentry_operations efivarfs_d_ops = { 118 .d_compare = efivarfs_d_compare, 119 .d_hash = efivarfs_d_hash, 120 .d_delete = always_delete_dentry, 121 }; 122 123 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) 124 { 125 struct dentry *d; 126 struct qstr q; 127 int err; 128 129 q.name = name; 130 q.len = strlen(name); 131 132 err = efivarfs_d_hash(parent, &q); 133 if (err) 134 return ERR_PTR(err); 135 136 d = d_alloc(parent, &q); 137 if (d) 138 return d; 139 140 return ERR_PTR(-ENOMEM); 141 } 142 143 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, 144 unsigned long name_size, void *data) 145 { 146 struct super_block *sb = (struct super_block *)data; 147 struct efivar_entry *entry; 148 struct inode *inode = NULL; 149 struct dentry *dentry, *root = sb->s_root; 150 unsigned long size = 0; 151 char *name; 152 int len; 153 int err = -ENOMEM; 154 bool is_removable = false; 155 156 if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) 157 return 0; 158 159 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 160 if (!entry) 161 return err; 162 163 memcpy(entry->var.VariableName, name16, name_size); 164 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); 165 166 len = ucs2_utf8size(entry->var.VariableName); 167 168 /* name, plus '-', plus GUID, plus NUL*/ 169 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); 170 if (!name) 171 goto fail; 172 173 ucs2_as_utf8(name, entry->var.VariableName, len); 174 175 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len)) 176 is_removable = true; 177 178 name[len] = '-'; 179 180 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1); 181 182 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; 183 184 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */ 185 strreplace(name, '/', '!'); 186 187 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, 188 is_removable); 189 if (!inode) 190 goto fail_name; 191 192 dentry = efivarfs_alloc_dentry(root, name); 193 if (IS_ERR(dentry)) { 194 err = PTR_ERR(dentry); 195 goto fail_inode; 196 } 197 198 __efivar_entry_get(entry, NULL, &size, NULL); 199 __efivar_entry_add(entry, &efivarfs_list); 200 201 /* copied by the above to local storage in the dentry. */ 202 kfree(name); 203 204 inode_lock(inode); 205 inode->i_private = entry; 206 i_size_write(inode, size + sizeof(entry->var.Attributes)); 207 inode_unlock(inode); 208 d_add(dentry, inode); 209 210 return 0; 211 212 fail_inode: 213 iput(inode); 214 fail_name: 215 kfree(name); 216 fail: 217 kfree(entry); 218 return err; 219 } 220 221 static int efivarfs_destroy(struct efivar_entry *entry, void *data) 222 { 223 efivar_entry_remove(entry); 224 kfree(entry); 225 return 0; 226 } 227 228 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) 229 { 230 struct inode *inode = NULL; 231 struct dentry *root; 232 int err; 233 234 if (!efivar_is_available()) 235 return -EOPNOTSUPP; 236 237 sb->s_maxbytes = MAX_LFS_FILESIZE; 238 sb->s_blocksize = PAGE_SIZE; 239 sb->s_blocksize_bits = PAGE_SHIFT; 240 sb->s_magic = EFIVARFS_MAGIC; 241 sb->s_op = &efivarfs_ops; 242 sb->s_d_op = &efivarfs_d_ops; 243 sb->s_time_gran = 1; 244 245 if (!efivar_supports_writes()) 246 sb->s_flags |= SB_RDONLY; 247 248 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); 249 if (!inode) 250 return -ENOMEM; 251 inode->i_op = &efivarfs_dir_inode_operations; 252 253 root = d_make_root(inode); 254 sb->s_root = root; 255 if (!root) 256 return -ENOMEM; 257 258 INIT_LIST_HEAD(&efivarfs_list); 259 260 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list); 261 if (err) 262 efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL); 263 264 return err; 265 } 266 267 static int efivarfs_get_tree(struct fs_context *fc) 268 { 269 return get_tree_single(fc, efivarfs_fill_super); 270 } 271 272 static const struct fs_context_operations efivarfs_context_ops = { 273 .get_tree = efivarfs_get_tree, 274 }; 275 276 static int efivarfs_init_fs_context(struct fs_context *fc) 277 { 278 fc->ops = &efivarfs_context_ops; 279 return 0; 280 } 281 282 static void efivarfs_kill_sb(struct super_block *sb) 283 { 284 kill_litter_super(sb); 285 286 if (!efivar_is_available()) 287 return; 288 289 /* Remove all entries and destroy */ 290 efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL); 291 } 292 293 static struct file_system_type efivarfs_type = { 294 .owner = THIS_MODULE, 295 .name = "efivarfs", 296 .init_fs_context = efivarfs_init_fs_context, 297 .kill_sb = efivarfs_kill_sb, 298 }; 299 300 static __init int efivarfs_init(void) 301 { 302 return register_filesystem(&efivarfs_type); 303 } 304 305 static __exit void efivarfs_exit(void) 306 { 307 unregister_filesystem(&efivarfs_type); 308 } 309 310 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); 311 MODULE_DESCRIPTION("EFI Variable Filesystem"); 312 MODULE_LICENSE("GPL"); 313 MODULE_ALIAS_FS("efivarfs"); 314 315 module_init(efivarfs_init); 316 module_exit(efivarfs_exit); 317