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/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> 20 21#include "internal.h" 22 23static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event, 24 void *data) 25{ 26 struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb); 27 28 switch (event) { 29 case EFIVAR_OPS_RDONLY: 30 sfi->sb->s_flags |= SB_RDONLY; 31 break; 32 case EFIVAR_OPS_RDWR: 33 sfi->sb->s_flags &= ~SB_RDONLY; 34 break; 35 default: 36 return NOTIFY_DONE; 37 } 38 39 return NOTIFY_OK; 40} 41 42static void efivarfs_evict_inode(struct inode *inode) 43{ 44 clear_inode(inode); 45} 46 47static int efivarfs_show_options(struct seq_file *m, struct dentry *root) 48{ 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; 52 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)); 59 return 0; 60} 61 62static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) 63{ 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); 69 efi_status_t status; 70 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, 75 &remaining_space, 76 &max_variable_size); 77 if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED) 78 pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n", 79 status); 80 } 81 82 /* 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 86 */ 87 buf->f_bsize = 1; 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); 93 94 /* 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. 98 */ 99 if (remaining_space > efivar_reserved_space()) 100 buf->f_bavail = remaining_space - efivar_reserved_space(); 101 else 102 buf->f_bavail = 0; 103 104 return 0; 105} 106static 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, 111}; 112 113/* 114 * Compare two efivarfs file names. 115 * 116 * An efivarfs filename is composed of two parts, 117 * 118 * 1. A case-sensitive variable name 119 * 2. A case-insensitive GUID 120 * 121 * So we need to perform a case-sensitive match on part 1 and a 122 * case-insensitive match on part 2. 123 */ 124static int efivarfs_d_compare(const struct dentry *dentry, 125 unsigned int len, const char *str, 126 const struct qstr *name) 127{ 128 int guid = len - EFI_VARIABLE_GUID_LEN; 129 130 if (name->len != len) 131 return 1; 132 133 /* Case-sensitive compare for the variable name */ 134 if (memcmp(str, name->name, guid)) 135 return 1; 136 137 /* Case-insensitive compare for the GUID */ 138 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); 139} 140 141static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) 142{ 143 unsigned long hash = init_name_hash(dentry); 144 const unsigned char *s = qstr->name; 145 unsigned int len = qstr->len; 146 147 if (!efivarfs_valid_name(s, len)) 148 return -EINVAL; 149 150 while (len-- > EFI_VARIABLE_GUID_LEN) 151 hash = partial_name_hash(*s++, hash); 152 153 /* GUID is case-insensitive. */ 154 while (len--) 155 hash = partial_name_hash(tolower(*s++), hash); 156 157 qstr->hash = end_name_hash(hash); 158 return 0; 159} 160 161static 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, 165}; 166 167static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) 168{ 169 struct dentry *d; 170 struct qstr q; 171 int err; 172 173 q.name = name; 174 q.len = strlen(name); 175 176 err = efivarfs_d_hash(parent, &q); 177 if (err) 178 return ERR_PTR(err); 179 180 d = d_alloc(parent, &q); 181 if (d) 182 return d; 183 184 return ERR_PTR(-ENOMEM); 185} 186 187static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, 188 unsigned long name_size, void *data, 189 struct list_head *list) 190{ 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; 196 char *name; 197 int len; 198 int err = -ENOMEM; 199 bool is_removable = false; 200 201 if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) 202 return 0; 203 204 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 205 if (!entry) 206 return err; 207 208 memcpy(entry->var.VariableName, name16, name_size); 209 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); 210 211 len = ucs2_utf8size(entry->var.VariableName); 212 213 /* name, plus '-', plus GUID, plus NUL*/ 214 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); 215 if (!name) 216 goto fail; 217 218 ucs2_as_utf8(name, entry->var.VariableName, len); 219 220 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len)) 221 is_removable = true; 222 223 name[len] = '-'; 224 225 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1); 226 227 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; 228 229 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */ 230 strreplace(name, '/', '!'); 231 232 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, 233 is_removable); 234 if (!inode) 235 goto fail_name; 236 237 dentry = efivarfs_alloc_dentry(root, name); 238 if (IS_ERR(dentry)) { 239 err = PTR_ERR(dentry); 240 goto fail_inode; 241 } 242 243 __efivar_entry_get(entry, NULL, &size, NULL); 244 __efivar_entry_add(entry, list); 245 246 /* copied by the above to local storage in the dentry. */ 247 kfree(name); 248 249 inode_lock(inode); 250 inode->i_private = entry; 251 i_size_write(inode, size + sizeof(entry->var.Attributes)); 252 inode_unlock(inode); 253 d_add(dentry, inode); 254 255 return 0; 256 257fail_inode: 258 iput(inode); 259fail_name: 260 kfree(name); 261fail: 262 kfree(entry); 263 return err; 264} 265 266static int efivarfs_destroy(struct efivar_entry *entry, void *data) 267{ 268 efivar_entry_remove(entry); 269 kfree(entry); 270 return 0; 271} 272 273enum { 274 Opt_uid, Opt_gid, 275}; 276 277static const struct fs_parameter_spec efivarfs_parameters[] = { 278 fsparam_u32("uid", Opt_uid), 279 fsparam_u32("gid", Opt_gid), 280 {}, 281}; 282 283static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param) 284{ 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; 288 int opt; 289 290 opt = fs_parse(fc, efivarfs_parameters, param, &result); 291 if (opt < 0) 292 return opt; 293 294 switch (opt) { 295 case Opt_uid: 296 opts->uid = make_kuid(current_user_ns(), result.uint_32); 297 if (!uid_valid(opts->uid)) 298 return -EINVAL; 299 break; 300 case Opt_gid: 301 opts->gid = make_kgid(current_user_ns(), result.uint_32); 302 if (!gid_valid(opts->gid)) 303 return -EINVAL; 304 break; 305 default: 306 return -EINVAL; 307 } 308 309 return 0; 310} 311 312static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) 313{ 314 struct efivarfs_fs_info *sfi = sb->s_fs_info; 315 struct inode *inode = NULL; 316 struct dentry *root; 317 int err; 318 319 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; 325 sb->s_time_gran = 1; 326 327 if (!efivar_supports_writes()) 328 sb->s_flags |= SB_RDONLY; 329 330 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); 331 if (!inode) 332 return -ENOMEM; 333 inode->i_op = &efivarfs_dir_inode_operations; 334 335 root = d_make_root(inode); 336 sb->s_root = root; 337 if (!root) 338 return -ENOMEM; 339 340 sfi->sb = sb; 341 sfi->nb.notifier_call = efivarfs_ops_notifier; 342 err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb); 343 if (err) 344 return err; 345 346 return efivar_init(efivarfs_callback, sb, &sfi->efivarfs_list); 347} 348 349static int efivarfs_get_tree(struct fs_context *fc) 350{ 351 return get_tree_single(fc, efivarfs_fill_super); 352} 353 354static int efivarfs_reconfigure(struct fs_context *fc) 355{ 356 if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) { 357 pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n"); 358 return -EINVAL; 359 } 360 361 return 0; 362} 363 364static const struct fs_context_operations efivarfs_context_ops = { 365 .get_tree = efivarfs_get_tree, 366 .parse_param = efivarfs_parse_param, 367 .reconfigure = efivarfs_reconfigure, 368}; 369 370static int efivarfs_init_fs_context(struct fs_context *fc) 371{ 372 struct efivarfs_fs_info *sfi; 373 374 if (!efivar_is_available()) 375 return -EOPNOTSUPP; 376 377 sfi = kzalloc(sizeof(*sfi), GFP_KERNEL); 378 if (!sfi) 379 return -ENOMEM; 380 381 INIT_LIST_HEAD(&sfi->efivarfs_list); 382 383 sfi->mount_opts.uid = GLOBAL_ROOT_UID; 384 sfi->mount_opts.gid = GLOBAL_ROOT_GID; 385 386 fc->s_fs_info = sfi; 387 fc->ops = &efivarfs_context_ops; 388 return 0; 389} 390 391static void efivarfs_kill_sb(struct super_block *sb) 392{ 393 struct efivarfs_fs_info *sfi = sb->s_fs_info; 394 395 blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb); 396 kill_litter_super(sb); 397 398 /* Remove all entries and destroy */ 399 efivar_entry_iter(efivarfs_destroy, &sfi->efivarfs_list, NULL); 400 kfree(sfi); 401} 402 403static struct file_system_type efivarfs_type = { 404 .owner = THIS_MODULE, 405 .name = "efivarfs", 406 .init_fs_context = efivarfs_init_fs_context, 407 .kill_sb = efivarfs_kill_sb, 408 .parameters = efivarfs_parameters, 409}; 410 411static __init int efivarfs_init(void) 412{ 413 return register_filesystem(&efivarfs_type); 414} 415 416static __exit void efivarfs_exit(void) 417{ 418 unregister_filesystem(&efivarfs_type); 419} 420 421MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); 422MODULE_DESCRIPTION("EFI Variable Filesystem"); 423MODULE_LICENSE("GPL"); 424MODULE_ALIAS_FS("efivarfs"); 425 426module_init(efivarfs_init); 427module_exit(efivarfs_exit); 428