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 17 #include "internal.h" 18 19 LIST_HEAD(efivarfs_list); 20 21 static void efivarfs_evict_inode(struct inode *inode) 22 { 23 clear_inode(inode); 24 } 25 26 static const struct super_operations efivarfs_ops = { 27 .statfs = simple_statfs, 28 .drop_inode = generic_delete_inode, 29 .evict_inode = efivarfs_evict_inode, 30 }; 31 32 /* 33 * Compare two efivarfs file names. 34 * 35 * An efivarfs filename is composed of two parts, 36 * 37 * 1. A case-sensitive variable name 38 * 2. A case-insensitive GUID 39 * 40 * So we need to perform a case-sensitive match on part 1 and a 41 * case-insensitive match on part 2. 42 */ 43 static int efivarfs_d_compare(const struct dentry *dentry, 44 unsigned int len, const char *str, 45 const struct qstr *name) 46 { 47 int guid = len - EFI_VARIABLE_GUID_LEN; 48 49 if (name->len != len) 50 return 1; 51 52 /* Case-sensitive compare for the variable name */ 53 if (memcmp(str, name->name, guid)) 54 return 1; 55 56 /* Case-insensitive compare for the GUID */ 57 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); 58 } 59 60 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) 61 { 62 unsigned long hash = init_name_hash(dentry); 63 const unsigned char *s = qstr->name; 64 unsigned int len = qstr->len; 65 66 if (!efivarfs_valid_name(s, len)) 67 return -EINVAL; 68 69 while (len-- > EFI_VARIABLE_GUID_LEN) 70 hash = partial_name_hash(*s++, hash); 71 72 /* GUID is case-insensitive. */ 73 while (len--) 74 hash = partial_name_hash(tolower(*s++), hash); 75 76 qstr->hash = end_name_hash(hash); 77 return 0; 78 } 79 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, 84 }; 85 86 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) 87 { 88 struct dentry *d; 89 struct qstr q; 90 int err; 91 92 q.name = name; 93 q.len = strlen(name); 94 95 err = efivarfs_d_hash(parent, &q); 96 if (err) 97 return ERR_PTR(err); 98 99 d = d_alloc(parent, &q); 100 if (d) 101 return d; 102 103 return ERR_PTR(-ENOMEM); 104 } 105 106 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, 107 unsigned long name_size, void *data) 108 { 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; 114 char *name; 115 int len; 116 int err = -ENOMEM; 117 bool is_removable = false; 118 119 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 120 if (!entry) 121 return err; 122 123 memcpy(entry->var.VariableName, name16, name_size); 124 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); 125 126 len = ucs2_utf8size(entry->var.VariableName); 127 128 /* name, plus '-', plus GUID, plus NUL*/ 129 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); 130 if (!name) 131 goto fail; 132 133 ucs2_as_utf8(name, entry->var.VariableName, len); 134 135 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len)) 136 is_removable = true; 137 138 name[len] = '-'; 139 140 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1); 141 142 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; 143 144 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, 145 is_removable); 146 if (!inode) 147 goto fail_name; 148 149 dentry = efivarfs_alloc_dentry(root, name); 150 if (IS_ERR(dentry)) { 151 err = PTR_ERR(dentry); 152 goto fail_inode; 153 } 154 155 efivar_entry_size(entry, &size); 156 err = efivar_entry_add(entry, &efivarfs_list); 157 if (err) 158 goto fail_inode; 159 160 /* copied by the above to local storage in the dentry. */ 161 kfree(name); 162 163 inode_lock(inode); 164 inode->i_private = entry; 165 i_size_write(inode, size + sizeof(entry->var.Attributes)); 166 inode_unlock(inode); 167 d_add(dentry, inode); 168 169 return 0; 170 171 fail_inode: 172 iput(inode); 173 fail_name: 174 kfree(name); 175 fail: 176 kfree(entry); 177 return err; 178 } 179 180 static int efivarfs_destroy(struct efivar_entry *entry, void *data) 181 { 182 int err = efivar_entry_remove(entry); 183 184 if (err) 185 return err; 186 kfree(entry); 187 return 0; 188 } 189 190 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) 191 { 192 struct inode *inode = NULL; 193 struct dentry *root; 194 int err; 195 196 sb->s_maxbytes = MAX_LFS_FILESIZE; 197 sb->s_blocksize = PAGE_SIZE; 198 sb->s_blocksize_bits = PAGE_SHIFT; 199 sb->s_magic = EFIVARFS_MAGIC; 200 sb->s_op = &efivarfs_ops; 201 sb->s_d_op = &efivarfs_d_ops; 202 sb->s_time_gran = 1; 203 204 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); 205 if (!inode) 206 return -ENOMEM; 207 inode->i_op = &efivarfs_dir_inode_operations; 208 209 root = d_make_root(inode); 210 sb->s_root = root; 211 if (!root) 212 return -ENOMEM; 213 214 INIT_LIST_HEAD(&efivarfs_list); 215 216 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list); 217 if (err) 218 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); 219 220 return err; 221 } 222 223 static int efivarfs_get_tree(struct fs_context *fc) 224 { 225 return get_tree_single(fc, efivarfs_fill_super); 226 } 227 228 static const struct fs_context_operations efivarfs_context_ops = { 229 .get_tree = efivarfs_get_tree, 230 }; 231 232 static int efivarfs_init_fs_context(struct fs_context *fc) 233 { 234 fc->ops = &efivarfs_context_ops; 235 return 0; 236 } 237 238 static void efivarfs_kill_sb(struct super_block *sb) 239 { 240 kill_litter_super(sb); 241 242 /* Remove all entries and destroy */ 243 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); 244 } 245 246 static struct file_system_type efivarfs_type = { 247 .owner = THIS_MODULE, 248 .name = "efivarfs", 249 .init_fs_context = efivarfs_init_fs_context, 250 .kill_sb = efivarfs_kill_sb, 251 }; 252 253 static __init int efivarfs_init(void) 254 { 255 if (!efi_rt_services_supported(EFI_RT_SUPPORTED_VARIABLE_SERVICES)) 256 return -ENODEV; 257 258 if (!efivars_kobject()) 259 return -ENODEV; 260 261 return register_filesystem(&efivarfs_type); 262 } 263 264 static __exit void efivarfs_exit(void) 265 { 266 unregister_filesystem(&efivarfs_type); 267 } 268 269 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); 270 MODULE_DESCRIPTION("EFI Variable Filesystem"); 271 MODULE_LICENSE("GPL"); 272 MODULE_ALIAS_FS("efivarfs"); 273 274 module_init(efivarfs_init); 275 module_exit(efivarfs_exit); 276