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 efivarfs_get_inode(struct super_block * sb,const struct inode * dir,int mode,dev_t dev,bool is_removable)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->i_ctime = current_time(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 */ efivarfs_valid_name(const char * str,int len)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 efivarfs_create(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)73 static int efivarfs_create(struct user_namespace *mnt_userns, 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 95 if (efivar_variable_is_removable(var->var.VendorGuid, 96 dentry->d_name.name, namelen)) 97 is_removable = true; 98 99 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable); 100 if (!inode) { 101 err = -ENOMEM; 102 goto out; 103 } 104 105 for (i = 0; i < namelen; i++) 106 var->var.VariableName[i] = dentry->d_name.name[i]; 107 108 var->var.VariableName[i] = '\0'; 109 110 inode->i_private = var; 111 kmemleak_ignore(var); 112 113 err = efivar_entry_add(var, &efivarfs_list); 114 if (err) 115 goto out; 116 117 d_instantiate(dentry, inode); 118 dget(dentry); 119 out: 120 if (err) { 121 kfree(var); 122 if (inode) 123 iput(inode); 124 } 125 return err; 126 } 127 efivarfs_unlink(struct inode * dir,struct dentry * dentry)128 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 129 { 130 struct efivar_entry *var = d_inode(dentry)->i_private; 131 132 if (efivar_entry_delete(var)) 133 return -EINVAL; 134 135 drop_nlink(d_inode(dentry)); 136 dput(dentry); 137 return 0; 138 }; 139 140 const struct inode_operations efivarfs_dir_inode_operations = { 141 .lookup = simple_lookup, 142 .unlink = efivarfs_unlink, 143 .create = efivarfs_create, 144 }; 145 146 static int efivarfs_fileattr_get(struct dentry * dentry,struct fileattr * fa)147 efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa) 148 { 149 unsigned int i_flags; 150 unsigned int flags = 0; 151 152 i_flags = d_inode(dentry)->i_flags; 153 if (i_flags & S_IMMUTABLE) 154 flags |= FS_IMMUTABLE_FL; 155 156 fileattr_fill_flags(fa, flags); 157 158 return 0; 159 } 160 161 static int efivarfs_fileattr_set(struct user_namespace * mnt_userns,struct dentry * dentry,struct fileattr * fa)162 efivarfs_fileattr_set(struct user_namespace *mnt_userns, 163 struct dentry *dentry, struct fileattr *fa) 164 { 165 unsigned int i_flags = 0; 166 167 if (fileattr_has_fsx(fa)) 168 return -EOPNOTSUPP; 169 170 if (fa->flags & ~FS_IMMUTABLE_FL) 171 return -EOPNOTSUPP; 172 173 if (fa->flags & FS_IMMUTABLE_FL) 174 i_flags |= S_IMMUTABLE; 175 176 inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE); 177 178 return 0; 179 } 180 181 static const struct inode_operations efivarfs_file_inode_operations = { 182 .fileattr_get = efivarfs_fileattr_get, 183 .fileattr_set = efivarfs_fileattr_set, 184 }; 185