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/efi.h> 11 #include <linux/fs.h> 12 #include <linux/ctype.h> 13 #include <linux/slab.h> 14 #include <linux/uuid.h> 15 16 #include "internal.h" 17 18 struct inode *efivarfs_get_inode(struct super_block *sb, 19 const struct inode *dir, int mode, 20 dev_t dev, bool is_removable) 21 { 22 struct inode *inode = new_inode(sb); 23 24 if (inode) { 25 inode->i_ino = get_next_ino(); 26 inode->i_mode = mode; 27 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); 28 inode->i_flags = is_removable ? 0 : S_IMMUTABLE; 29 switch (mode & S_IFMT) { 30 case S_IFREG: 31 inode->i_fop = &efivarfs_file_operations; 32 break; 33 case S_IFDIR: 34 inode->i_op = &efivarfs_dir_inode_operations; 35 inode->i_fop = &simple_dir_operations; 36 inc_nlink(inode); 37 break; 38 } 39 } 40 return inode; 41 } 42 43 /* 44 * Return true if 'str' is a valid efivarfs filename of the form, 45 * 46 * VariableName-12345678-1234-1234-1234-1234567891bc 47 */ 48 bool efivarfs_valid_name(const char *str, int len) 49 { 50 const char *s = str + len - EFI_VARIABLE_GUID_LEN; 51 52 /* 53 * We need a GUID, plus at least one letter for the variable name, 54 * plus the '-' separator 55 */ 56 if (len < EFI_VARIABLE_GUID_LEN + 2) 57 return false; 58 59 /* GUID must be preceded by a '-' */ 60 if (*(s - 1) != '-') 61 return false; 62 63 /* 64 * Validate that 's' is of the correct format, e.g. 65 * 66 * 12345678-1234-1234-1234-123456789abc 67 */ 68 return uuid_is_valid(s); 69 } 70 71 static int efivarfs_create(struct inode *dir, struct dentry *dentry, 72 umode_t mode, bool excl) 73 { 74 struct inode *inode = NULL; 75 struct efivar_entry *var; 76 int namelen, i = 0, err = 0; 77 bool is_removable = false; 78 79 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) 80 return -EINVAL; 81 82 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); 83 if (!var) 84 return -ENOMEM; 85 86 /* length of the variable name itself: remove GUID and separator */ 87 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; 88 89 uuid_le_to_bin(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); 90 91 if (efivar_variable_is_removable(var->var.VendorGuid, 92 dentry->d_name.name, namelen)) 93 is_removable = true; 94 95 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable); 96 if (!inode) { 97 err = -ENOMEM; 98 goto out; 99 } 100 101 for (i = 0; i < namelen; i++) 102 var->var.VariableName[i] = dentry->d_name.name[i]; 103 104 var->var.VariableName[i] = '\0'; 105 106 inode->i_private = var; 107 108 err = efivar_entry_add(var, &efivarfs_list); 109 if (err) 110 goto out; 111 112 d_instantiate(dentry, inode); 113 dget(dentry); 114 out: 115 if (err) { 116 kfree(var); 117 if (inode) 118 iput(inode); 119 } 120 return err; 121 } 122 123 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 124 { 125 struct efivar_entry *var = d_inode(dentry)->i_private; 126 127 if (efivar_entry_delete(var)) 128 return -EINVAL; 129 130 drop_nlink(d_inode(dentry)); 131 dput(dentry); 132 return 0; 133 }; 134 135 const struct inode_operations efivarfs_dir_inode_operations = { 136 .lookup = simple_lookup, 137 .unlink = efivarfs_unlink, 138 .create = efivarfs_create, 139 }; 140