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/efi.h> 8 #include <linux/fs.h> 9 #include <linux/ctype.h> 10 #include <linux/slab.h> 11 #include <linux/uuid.h> 12 13 #include "internal.h" 14 15 struct inode *efivarfs_get_inode(struct super_block *sb, 16 const struct inode *dir, int mode, 17 dev_t dev, bool is_removable) 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(inode); 25 inode->i_flags = is_removable ? 0 : S_IMMUTABLE; 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 const char *s = str + len - EFI_VARIABLE_GUID_LEN; 48 49 /* 50 * We need a GUID, plus at least one letter for the variable name, 51 * plus the '-' separator 52 */ 53 if (len < EFI_VARIABLE_GUID_LEN + 2) 54 return false; 55 56 /* GUID must be preceded by a '-' */ 57 if (*(s - 1) != '-') 58 return false; 59 60 /* 61 * Validate that 's' is of the correct format, e.g. 62 * 63 * 12345678-1234-1234-1234-123456789abc 64 */ 65 return uuid_is_valid(s); 66 } 67 68 static int efivarfs_create(struct inode *dir, struct dentry *dentry, 69 umode_t mode, bool excl) 70 { 71 struct inode *inode = NULL; 72 struct efivar_entry *var; 73 int namelen, i = 0, err = 0; 74 bool is_removable = false; 75 76 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) 77 return -EINVAL; 78 79 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); 80 if (!var) 81 return -ENOMEM; 82 83 /* length of the variable name itself: remove GUID and separator */ 84 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; 85 86 err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); 87 if (err) 88 goto out; 89 90 if (efivar_variable_is_removable(var->var.VendorGuid, 91 dentry->d_name.name, namelen)) 92 is_removable = true; 93 94 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable); 95 if (!inode) { 96 err = -ENOMEM; 97 goto out; 98 } 99 100 for (i = 0; i < namelen; i++) 101 var->var.VariableName[i] = dentry->d_name.name[i]; 102 103 var->var.VariableName[i] = '\0'; 104 105 inode->i_private = var; 106 107 err = efivar_entry_add(var, &efivarfs_list); 108 if (err) 109 goto out; 110 111 d_instantiate(dentry, inode); 112 dget(dentry); 113 out: 114 if (err) { 115 kfree(var); 116 if (inode) 117 iput(inode); 118 } 119 return err; 120 } 121 122 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 123 { 124 struct efivar_entry *var = d_inode(dentry)->i_private; 125 126 if (efivar_entry_delete(var)) 127 return -EINVAL; 128 129 drop_nlink(d_inode(dentry)); 130 dput(dentry); 131 return 0; 132 }; 133 134 const struct inode_operations efivarfs_dir_inode_operations = { 135 .lookup = simple_lookup, 136 .unlink = efivarfs_unlink, 137 .create = efivarfs_create, 138 }; 139