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 /* Some UEFI firmware does not implement QueryVariableInfo() */ 36 storage_space = remaining_space = 0; 37 if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) { 38 status = efivar_query_variable_info(attr, &storage_space, 39 &remaining_space, 40 &max_variable_size); 41 if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED) 42 pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n", 43 status); 44 } 45 46 /* 47 * This is not a normal filesystem, so no point in pretending it has a block 48 * size; we declare f_bsize to 1, so that we can then report the exact value 49 * sent by EFI QueryVariableInfo in f_blocks and f_bfree 50 */ 51 buf->f_bsize = 1; 52 buf->f_namelen = NAME_MAX; 53 buf->f_blocks = storage_space; 54 buf->f_bfree = remaining_space; 55 buf->f_type = dentry->d_sb->s_magic; 56 57 /* 58 * In f_bavail we declare the free space that the kernel will allow writing 59 * when the storage_paranoia x86 quirk is active. To use more, users 60 * should boot the kernel with efi_no_storage_paranoia. 61 */ 62 if (remaining_space > efivar_reserved_space()) 63 buf->f_bavail = remaining_space - efivar_reserved_space(); 64 else 65 buf->f_bavail = 0; 66 67 return 0; 68 } 69 static const struct super_operations efivarfs_ops = { 70 .statfs = efivarfs_statfs, 71 .drop_inode = generic_delete_inode, 72 .evict_inode = efivarfs_evict_inode, 73 }; 74 75 /* 76 * Compare two efivarfs file names. 77 * 78 * An efivarfs filename is composed of two parts, 79 * 80 * 1. A case-sensitive variable name 81 * 2. A case-insensitive GUID 82 * 83 * So we need to perform a case-sensitive match on part 1 and a 84 * case-insensitive match on part 2. 85 */ 86 static int efivarfs_d_compare(const struct dentry *dentry, 87 unsigned int len, const char *str, 88 const struct qstr *name) 89 { 90 int guid = len - EFI_VARIABLE_GUID_LEN; 91 92 if (name->len != len) 93 return 1; 94 95 /* Case-sensitive compare for the variable name */ 96 if (memcmp(str, name->name, guid)) 97 return 1; 98 99 /* Case-insensitive compare for the GUID */ 100 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); 101 } 102 103 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) 104 { 105 unsigned long hash = init_name_hash(dentry); 106 const unsigned char *s = qstr->name; 107 unsigned int len = qstr->len; 108 109 if (!efivarfs_valid_name(s, len)) 110 return -EINVAL; 111 112 while (len-- > EFI_VARIABLE_GUID_LEN) 113 hash = partial_name_hash(*s++, hash); 114 115 /* GUID is case-insensitive. */ 116 while (len--) 117 hash = partial_name_hash(tolower(*s++), hash); 118 119 qstr->hash = end_name_hash(hash); 120 return 0; 121 } 122 123 static const struct dentry_operations efivarfs_d_ops = { 124 .d_compare = efivarfs_d_compare, 125 .d_hash = efivarfs_d_hash, 126 .d_delete = always_delete_dentry, 127 }; 128 129 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) 130 { 131 struct dentry *d; 132 struct qstr q; 133 int err; 134 135 q.name = name; 136 q.len = strlen(name); 137 138 err = efivarfs_d_hash(parent, &q); 139 if (err) 140 return ERR_PTR(err); 141 142 d = d_alloc(parent, &q); 143 if (d) 144 return d; 145 146 return ERR_PTR(-ENOMEM); 147 } 148 149 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, 150 unsigned long name_size, void *data) 151 { 152 struct super_block *sb = (struct super_block *)data; 153 struct efivar_entry *entry; 154 struct inode *inode = NULL; 155 struct dentry *dentry, *root = sb->s_root; 156 unsigned long size = 0; 157 char *name; 158 int len; 159 int err = -ENOMEM; 160 bool is_removable = false; 161 162 if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) 163 return 0; 164 165 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 166 if (!entry) 167 return err; 168 169 memcpy(entry->var.VariableName, name16, name_size); 170 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); 171 172 len = ucs2_utf8size(entry->var.VariableName); 173 174 /* name, plus '-', plus GUID, plus NUL*/ 175 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); 176 if (!name) 177 goto fail; 178 179 ucs2_as_utf8(name, entry->var.VariableName, len); 180 181 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len)) 182 is_removable = true; 183 184 name[len] = '-'; 185 186 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1); 187 188 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; 189 190 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */ 191 strreplace(name, '/', '!'); 192 193 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, 194 is_removable); 195 if (!inode) 196 goto fail_name; 197 198 dentry = efivarfs_alloc_dentry(root, name); 199 if (IS_ERR(dentry)) { 200 err = PTR_ERR(dentry); 201 goto fail_inode; 202 } 203 204 __efivar_entry_get(entry, NULL, &size, NULL); 205 __efivar_entry_add(entry, &efivarfs_list); 206 207 /* copied by the above to local storage in the dentry. */ 208 kfree(name); 209 210 inode_lock(inode); 211 inode->i_private = entry; 212 i_size_write(inode, size + sizeof(entry->var.Attributes)); 213 inode_unlock(inode); 214 d_add(dentry, inode); 215 216 return 0; 217 218 fail_inode: 219 iput(inode); 220 fail_name: 221 kfree(name); 222 fail: 223 kfree(entry); 224 return err; 225 } 226 227 static int efivarfs_destroy(struct efivar_entry *entry, void *data) 228 { 229 efivar_entry_remove(entry); 230 kfree(entry); 231 return 0; 232 } 233 234 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) 235 { 236 struct inode *inode = NULL; 237 struct dentry *root; 238 int err; 239 240 if (!efivar_is_available()) 241 return -EOPNOTSUPP; 242 243 sb->s_maxbytes = MAX_LFS_FILESIZE; 244 sb->s_blocksize = PAGE_SIZE; 245 sb->s_blocksize_bits = PAGE_SHIFT; 246 sb->s_magic = EFIVARFS_MAGIC; 247 sb->s_op = &efivarfs_ops; 248 sb->s_d_op = &efivarfs_d_ops; 249 sb->s_time_gran = 1; 250 251 if (!efivar_supports_writes()) 252 sb->s_flags |= SB_RDONLY; 253 254 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); 255 if (!inode) 256 return -ENOMEM; 257 inode->i_op = &efivarfs_dir_inode_operations; 258 259 root = d_make_root(inode); 260 sb->s_root = root; 261 if (!root) 262 return -ENOMEM; 263 264 INIT_LIST_HEAD(&efivarfs_list); 265 266 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list); 267 if (err) 268 efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL); 269 270 return err; 271 } 272 273 static int efivarfs_get_tree(struct fs_context *fc) 274 { 275 return get_tree_single(fc, efivarfs_fill_super); 276 } 277 278 static const struct fs_context_operations efivarfs_context_ops = { 279 .get_tree = efivarfs_get_tree, 280 }; 281 282 static int efivarfs_init_fs_context(struct fs_context *fc) 283 { 284 fc->ops = &efivarfs_context_ops; 285 return 0; 286 } 287 288 static void efivarfs_kill_sb(struct super_block *sb) 289 { 290 kill_litter_super(sb); 291 292 if (!efivar_is_available()) 293 return; 294 295 /* Remove all entries and destroy */ 296 efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL); 297 } 298 299 static struct file_system_type efivarfs_type = { 300 .owner = THIS_MODULE, 301 .name = "efivarfs", 302 .init_fs_context = efivarfs_init_fs_context, 303 .kill_sb = efivarfs_kill_sb, 304 }; 305 306 static __init int efivarfs_init(void) 307 { 308 return register_filesystem(&efivarfs_type); 309 } 310 311 static __exit void efivarfs_exit(void) 312 { 313 unregister_filesystem(&efivarfs_type); 314 } 315 316 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); 317 MODULE_DESCRIPTION("EFI Variable Filesystem"); 318 MODULE_LICENSE("GPL"); 319 MODULE_ALIAS_FS("efivarfs"); 320 321 module_init(efivarfs_init); 322 module_exit(efivarfs_exit); 323