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 15 #include "internal.h" 16 17 struct inode *efivarfs_get_inode(struct super_block *sb, 18 const struct inode *dir, int mode, dev_t dev) 19 { 20 struct inode *inode = new_inode(sb); 21 22 if (inode) { 23 inode->i_ino = get_next_ino(); 24 inode->i_mode = mode; 25 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 26 switch (mode & S_IFMT) { 27 case S_IFREG: 28 inode->i_fop = &efivarfs_file_operations; 29 break; 30 case S_IFDIR: 31 inode->i_op = &efivarfs_dir_inode_operations; 32 inode->i_fop = &simple_dir_operations; 33 inc_nlink(inode); 34 break; 35 } 36 } 37 return inode; 38 } 39 40 /* 41 * Return true if 'str' is a valid efivarfs filename of the form, 42 * 43 * VariableName-12345678-1234-1234-1234-1234567891bc 44 */ 45 bool efivarfs_valid_name(const char *str, int len) 46 { 47 static const char dashes[EFI_VARIABLE_GUID_LEN] = { 48 [8] = 1, [13] = 1, [18] = 1, [23] = 1 49 }; 50 const char *s = str + len - EFI_VARIABLE_GUID_LEN; 51 int i; 52 53 /* 54 * We need a GUID, plus at least one letter for the variable name, 55 * plus the '-' separator 56 */ 57 if (len < EFI_VARIABLE_GUID_LEN + 2) 58 return false; 59 60 /* GUID must be preceded by a '-' */ 61 if (*(s - 1) != '-') 62 return false; 63 64 /* 65 * Validate that 's' is of the correct format, e.g. 66 * 67 * 12345678-1234-1234-1234-123456789abc 68 */ 69 for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) { 70 if (dashes[i]) { 71 if (*s++ != '-') 72 return false; 73 } else { 74 if (!isxdigit(*s++)) 75 return false; 76 } 77 } 78 79 return true; 80 } 81 82 static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid) 83 { 84 guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]); 85 guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]); 86 guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]); 87 guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]); 88 guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]); 89 guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]); 90 guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]); 91 guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]); 92 guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]); 93 guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]); 94 guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]); 95 guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]); 96 guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]); 97 guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]); 98 guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]); 99 guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]); 100 } 101 102 static int efivarfs_create(struct inode *dir, struct dentry *dentry, 103 umode_t mode, bool excl) 104 { 105 struct inode *inode; 106 struct efivar_entry *var; 107 int namelen, i = 0, err = 0; 108 109 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) 110 return -EINVAL; 111 112 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0); 113 if (!inode) 114 return -ENOMEM; 115 116 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); 117 if (!var) { 118 err = -ENOMEM; 119 goto out; 120 } 121 122 /* length of the variable name itself: remove GUID and separator */ 123 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; 124 125 efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1, 126 &var->var.VendorGuid); 127 128 for (i = 0; i < namelen; i++) 129 var->var.VariableName[i] = dentry->d_name.name[i]; 130 131 var->var.VariableName[i] = '\0'; 132 133 inode->i_private = var; 134 135 efivar_entry_add(var, &efivarfs_list); 136 d_instantiate(dentry, inode); 137 dget(dentry); 138 out: 139 if (err) { 140 kfree(var); 141 iput(inode); 142 } 143 return err; 144 } 145 146 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 147 { 148 struct efivar_entry *var = d_inode(dentry)->i_private; 149 150 if (efivar_entry_delete(var)) 151 return -EINVAL; 152 153 drop_nlink(d_inode(dentry)); 154 dput(dentry); 155 return 0; 156 }; 157 158 const struct inode_operations efivarfs_dir_inode_operations = { 159 .lookup = simple_lookup, 160 .unlink = efivarfs_unlink, 161 .create = efivarfs_create, 162 }; 163