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/kmemleak.h> 11 #include <linux/slab.h> 12 #include <linux/uuid.h> 13 #include <linux/fileattr.h> 14 15 #include "internal.h" 16 17 static const struct inode_operations efivarfs_file_inode_operations; 18 19 struct inode *efivarfs_get_inode(struct super_block *sb, 20 const struct inode *dir, int mode, 21 dev_t dev, bool is_removable) 22 { 23 struct inode *inode = new_inode(sb); 24 25 if (inode) { 26 inode->i_ino = get_next_ino(); 27 inode->i_mode = mode; 28 inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode); 29 inode->i_flags = is_removable ? 0 : S_IMMUTABLE; 30 switch (mode & S_IFMT) { 31 case S_IFREG: 32 inode->i_op = &efivarfs_file_inode_operations; 33 inode->i_fop = &efivarfs_file_operations; 34 break; 35 case S_IFDIR: 36 inode->i_op = &efivarfs_dir_inode_operations; 37 inode->i_fop = &simple_dir_operations; 38 inc_nlink(inode); 39 break; 40 } 41 } 42 return inode; 43 } 44 45 /* 46 * Return true if 'str' is a valid efivarfs filename of the form, 47 * 48 * VariableName-12345678-1234-1234-1234-1234567891bc 49 */ 50 bool efivarfs_valid_name(const char *str, int len) 51 { 52 const char *s = str + len - EFI_VARIABLE_GUID_LEN; 53 54 /* 55 * We need a GUID, plus at least one letter for the variable name, 56 * plus the '-' separator 57 */ 58 if (len < EFI_VARIABLE_GUID_LEN + 2) 59 return false; 60 61 /* GUID must be preceded by a '-' */ 62 if (*(s - 1) != '-') 63 return false; 64 65 /* 66 * Validate that 's' is of the correct format, e.g. 67 * 68 * 12345678-1234-1234-1234-123456789abc 69 */ 70 return uuid_is_valid(s); 71 } 72 73 static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir, 74 struct dentry *dentry, umode_t mode, bool excl) 75 { 76 struct inode *inode = NULL; 77 struct efivar_entry *var; 78 int namelen, i = 0, err = 0; 79 bool is_removable = false; 80 81 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) 82 return -EINVAL; 83 84 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); 85 if (!var) 86 return -ENOMEM; 87 88 /* length of the variable name itself: remove GUID and separator */ 89 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; 90 91 err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); 92 if (err) 93 goto out; 94 if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) { 95 err = -EPERM; 96 goto out; 97 } 98 99 if (efivar_variable_is_removable(var->var.VendorGuid, 100 dentry->d_name.name, namelen)) 101 is_removable = true; 102 103 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable); 104 if (!inode) { 105 err = -ENOMEM; 106 goto out; 107 } 108 109 for (i = 0; i < namelen; i++) 110 var->var.VariableName[i] = dentry->d_name.name[i]; 111 112 var->var.VariableName[i] = '\0'; 113 114 inode->i_private = var; 115 kmemleak_ignore(var); 116 117 err = efivar_entry_add(var, &efivarfs_list); 118 if (err) 119 goto out; 120 121 d_instantiate(dentry, inode); 122 dget(dentry); 123 out: 124 if (err) { 125 kfree(var); 126 if (inode) 127 iput(inode); 128 } 129 return err; 130 } 131 132 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 133 { 134 struct efivar_entry *var = d_inode(dentry)->i_private; 135 136 if (efivar_entry_delete(var)) 137 return -EINVAL; 138 139 drop_nlink(d_inode(dentry)); 140 dput(dentry); 141 return 0; 142 }; 143 144 const struct inode_operations efivarfs_dir_inode_operations = { 145 .lookup = simple_lookup, 146 .unlink = efivarfs_unlink, 147 .create = efivarfs_create, 148 }; 149 150 static int 151 efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa) 152 { 153 unsigned int i_flags; 154 unsigned int flags = 0; 155 156 i_flags = d_inode(dentry)->i_flags; 157 if (i_flags & S_IMMUTABLE) 158 flags |= FS_IMMUTABLE_FL; 159 160 fileattr_fill_flags(fa, flags); 161 162 return 0; 163 } 164 165 static int 166 efivarfs_fileattr_set(struct mnt_idmap *idmap, 167 struct dentry *dentry, struct fileattr *fa) 168 { 169 unsigned int i_flags = 0; 170 171 if (fileattr_has_fsx(fa)) 172 return -EOPNOTSUPP; 173 174 if (fa->flags & ~FS_IMMUTABLE_FL) 175 return -EOPNOTSUPP; 176 177 if (fa->flags & FS_IMMUTABLE_FL) 178 i_flags |= S_IMMUTABLE; 179 180 inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE); 181 182 return 0; 183 } 184 185 static const struct inode_operations efivarfs_file_inode_operations = { 186 .fileattr_get = efivarfs_fileattr_get, 187 .fileattr_set = efivarfs_fileattr_set, 188 }; 189