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 14 #include "internal.h" 15 16 struct inode *efivarfs_get_inode(struct super_block *sb, 17 const struct inode *dir, int mode, dev_t dev) 18 { 19 struct inode *inode = new_inode(sb); 20 21 if (inode) { 22 inode->i_ino = get_next_ino(); 23 inode->i_mode = mode; 24 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 25 switch (mode & S_IFMT) { 26 case S_IFREG: 27 inode->i_fop = &efivarfs_file_operations; 28 break; 29 case S_IFDIR: 30 inode->i_op = &efivarfs_dir_inode_operations; 31 inode->i_fop = &simple_dir_operations; 32 inc_nlink(inode); 33 break; 34 } 35 } 36 return inode; 37 } 38 39 /* 40 * Return true if 'str' is a valid efivarfs filename of the form, 41 * 42 * VariableName-12345678-1234-1234-1234-1234567891bc 43 */ 44 bool efivarfs_valid_name(const char *str, int len) 45 { 46 static const char dashes[EFI_VARIABLE_GUID_LEN] = { 47 [8] = 1, [13] = 1, [18] = 1, [23] = 1 48 }; 49 const char *s = str + len - EFI_VARIABLE_GUID_LEN; 50 int i; 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 for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) { 69 if (dashes[i]) { 70 if (*s++ != '-') 71 return false; 72 } else { 73 if (!isxdigit(*s++)) 74 return false; 75 } 76 } 77 78 return true; 79 } 80 81 static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid) 82 { 83 guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]); 84 guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]); 85 guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]); 86 guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]); 87 guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]); 88 guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]); 89 guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]); 90 guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]); 91 guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]); 92 guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]); 93 guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]); 94 guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]); 95 guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]); 96 guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]); 97 guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]); 98 guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]); 99 } 100 101 static int efivarfs_create(struct inode *dir, struct dentry *dentry, 102 umode_t mode, bool excl) 103 { 104 struct inode *inode; 105 struct efivar_entry *var; 106 int namelen, i = 0, err = 0; 107 108 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) 109 return -EINVAL; 110 111 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0); 112 if (!inode) 113 return -ENOMEM; 114 115 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); 116 if (!var) { 117 err = -ENOMEM; 118 goto out; 119 } 120 121 /* length of the variable name itself: remove GUID and separator */ 122 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; 123 124 efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1, 125 &var->var.VendorGuid); 126 127 for (i = 0; i < namelen; i++) 128 var->var.VariableName[i] = dentry->d_name.name[i]; 129 130 var->var.VariableName[i] = '\0'; 131 132 inode->i_private = var; 133 134 efivar_entry_add(var, &efivarfs_list); 135 d_instantiate(dentry, inode); 136 dget(dentry); 137 out: 138 if (err) { 139 kfree(var); 140 iput(inode); 141 } 142 return err; 143 } 144 145 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 146 { 147 struct efivar_entry *var = dentry->d_inode->i_private; 148 149 if (efivar_entry_delete(var)) 150 return -EINVAL; 151 152 drop_nlink(dentry->d_inode); 153 dput(dentry); 154 return 0; 155 }; 156 157 /* 158 * Handle negative dentry. 159 */ 160 static struct dentry *efivarfs_lookup(struct inode *dir, struct dentry *dentry, 161 unsigned int flags) 162 { 163 if (dentry->d_name.len > NAME_MAX) 164 return ERR_PTR(-ENAMETOOLONG); 165 d_add(dentry, NULL); 166 return NULL; 167 } 168 169 const struct inode_operations efivarfs_dir_inode_operations = { 170 .lookup = efivarfs_lookup, 171 .unlink = efivarfs_unlink, 172 .create = efivarfs_create, 173 }; 174