1 /* 2 * Copyright (C) 2012 Red Hat, Inc. 3 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 10 #include <linux/ctype.h> 11 #include <linux/efi.h> 12 #include <linux/fs.h> 13 #include <linux/module.h> 14 #include <linux/pagemap.h> 15 #include <linux/ucs2_string.h> 16 #include <linux/slab.h> 17 #include <linux/magic.h> 18 19 #include "internal.h" 20 21 LIST_HEAD(efivarfs_list); 22 23 static void efivarfs_evict_inode(struct inode *inode) 24 { 25 clear_inode(inode); 26 } 27 28 static const struct super_operations efivarfs_ops = { 29 .statfs = simple_statfs, 30 .drop_inode = generic_delete_inode, 31 .evict_inode = efivarfs_evict_inode, 32 .show_options = generic_show_options, 33 }; 34 35 static struct super_block *efivarfs_sb; 36 37 /* 38 * Compare two efivarfs file names. 39 * 40 * An efivarfs filename is composed of two parts, 41 * 42 * 1. A case-sensitive variable name 43 * 2. A case-insensitive GUID 44 * 45 * So we need to perform a case-sensitive match on part 1 and a 46 * case-insensitive match on part 2. 47 */ 48 static int efivarfs_d_compare(const struct dentry *dentry, 49 unsigned int len, const char *str, 50 const struct qstr *name) 51 { 52 int guid = len - EFI_VARIABLE_GUID_LEN; 53 54 if (name->len != len) 55 return 1; 56 57 /* Case-sensitive compare for the variable name */ 58 if (memcmp(str, name->name, guid)) 59 return 1; 60 61 /* Case-insensitive compare for the GUID */ 62 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); 63 } 64 65 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) 66 { 67 unsigned long hash = init_name_hash(dentry); 68 const unsigned char *s = qstr->name; 69 unsigned int len = qstr->len; 70 71 if (!efivarfs_valid_name(s, len)) 72 return -EINVAL; 73 74 while (len-- > EFI_VARIABLE_GUID_LEN) 75 hash = partial_name_hash(*s++, hash); 76 77 /* GUID is case-insensitive. */ 78 while (len--) 79 hash = partial_name_hash(tolower(*s++), hash); 80 81 qstr->hash = end_name_hash(hash); 82 return 0; 83 } 84 85 static const struct dentry_operations efivarfs_d_ops = { 86 .d_compare = efivarfs_d_compare, 87 .d_hash = efivarfs_d_hash, 88 .d_delete = always_delete_dentry, 89 }; 90 91 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) 92 { 93 struct dentry *d; 94 struct qstr q; 95 int err; 96 97 q.name = name; 98 q.len = strlen(name); 99 100 err = efivarfs_d_hash(parent, &q); 101 if (err) 102 return ERR_PTR(err); 103 104 d = d_alloc(parent, &q); 105 if (d) 106 return d; 107 108 return ERR_PTR(-ENOMEM); 109 } 110 111 static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, 112 unsigned long name_size, void *data) 113 { 114 struct super_block *sb = (struct super_block *)data; 115 struct efivar_entry *entry; 116 struct inode *inode = NULL; 117 struct dentry *dentry, *root = sb->s_root; 118 unsigned long size = 0; 119 char *name; 120 int len; 121 int err = -ENOMEM; 122 bool is_removable = false; 123 124 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 125 if (!entry) 126 return err; 127 128 memcpy(entry->var.VariableName, name16, name_size); 129 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); 130 131 len = ucs2_utf8size(entry->var.VariableName); 132 133 /* name, plus '-', plus GUID, plus NUL*/ 134 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); 135 if (!name) 136 goto fail; 137 138 ucs2_as_utf8(name, entry->var.VariableName, len); 139 140 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len)) 141 is_removable = true; 142 143 name[len] = '-'; 144 145 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1); 146 147 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; 148 149 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, 150 is_removable); 151 if (!inode) 152 goto fail_name; 153 154 dentry = efivarfs_alloc_dentry(root, name); 155 if (IS_ERR(dentry)) { 156 err = PTR_ERR(dentry); 157 goto fail_inode; 158 } 159 160 /* copied by the above to local storage in the dentry. */ 161 kfree(name); 162 163 efivar_entry_size(entry, &size); 164 efivar_entry_add(entry, &efivarfs_list); 165 166 inode_lock(inode); 167 inode->i_private = entry; 168 i_size_write(inode, size + sizeof(entry->var.Attributes)); 169 inode_unlock(inode); 170 d_add(dentry, inode); 171 172 return 0; 173 174 fail_inode: 175 iput(inode); 176 fail_name: 177 kfree(name); 178 fail: 179 kfree(entry); 180 return err; 181 } 182 183 static int efivarfs_destroy(struct efivar_entry *entry, void *data) 184 { 185 efivar_entry_remove(entry); 186 kfree(entry); 187 return 0; 188 } 189 190 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) 191 { 192 struct inode *inode = NULL; 193 struct dentry *root; 194 int err; 195 196 efivarfs_sb = sb; 197 198 sb->s_maxbytes = MAX_LFS_FILESIZE; 199 sb->s_blocksize = PAGE_SIZE; 200 sb->s_blocksize_bits = PAGE_SHIFT; 201 sb->s_magic = EFIVARFS_MAGIC; 202 sb->s_op = &efivarfs_ops; 203 sb->s_d_op = &efivarfs_d_ops; 204 sb->s_time_gran = 1; 205 206 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); 207 if (!inode) 208 return -ENOMEM; 209 inode->i_op = &efivarfs_dir_inode_operations; 210 211 root = d_make_root(inode); 212 sb->s_root = root; 213 if (!root) 214 return -ENOMEM; 215 216 INIT_LIST_HEAD(&efivarfs_list); 217 218 err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list); 219 if (err) 220 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); 221 222 return err; 223 } 224 225 static struct dentry *efivarfs_mount(struct file_system_type *fs_type, 226 int flags, const char *dev_name, void *data) 227 { 228 return mount_single(fs_type, flags, data, efivarfs_fill_super); 229 } 230 231 static void efivarfs_kill_sb(struct super_block *sb) 232 { 233 kill_litter_super(sb); 234 efivarfs_sb = NULL; 235 236 /* Remove all entries and destroy */ 237 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); 238 } 239 240 static struct file_system_type efivarfs_type = { 241 .owner = THIS_MODULE, 242 .name = "efivarfs", 243 .mount = efivarfs_mount, 244 .kill_sb = efivarfs_kill_sb, 245 }; 246 247 static __init int efivarfs_init(void) 248 { 249 if (!efi_enabled(EFI_RUNTIME_SERVICES)) 250 return -ENODEV; 251 252 if (!efivars_kobject()) 253 return -ENODEV; 254 255 return register_filesystem(&efivarfs_type); 256 } 257 258 static __exit void efivarfs_exit(void) 259 { 260 unregister_filesystem(&efivarfs_type); 261 } 262 263 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); 264 MODULE_DESCRIPTION("EFI Variable Filesystem"); 265 MODULE_LICENSE("GPL"); 266 MODULE_ALIAS_FS("efivarfs"); 267 268 module_init(efivarfs_init); 269 module_exit(efivarfs_exit); 270