194 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*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 17static const struct inode_operations efivarfs_file_inode_operations;18 19struct 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 struct efivarfs_fs_info *fsi = sb->s_fs_info;25 struct efivarfs_mount_opts *opts = &fsi->mount_opts;26 27 if (inode) {28 inode->i_uid = opts->uid;29 inode->i_gid = opts->gid;30 inode->i_ino = get_next_ino();31 inode->i_mode = mode;32 simple_inode_init_ts(inode);33 inode->i_flags = is_removable ? 0 : S_IMMUTABLE;34 switch (mode & S_IFMT) {35 case S_IFREG:36 inode->i_op = &efivarfs_file_inode_operations;37 inode->i_fop = &efivarfs_file_operations;38 break;39 case S_IFDIR:40 inode->i_op = &efivarfs_dir_inode_operations;41 inode->i_fop = &simple_dir_operations;42 inc_nlink(inode);43 break;44 }45 }46 return inode;47}48 49/*50 * Return true if 'str' is a valid efivarfs filename of the form,51 *52 * VariableName-12345678-1234-1234-1234-1234567891bc53 */54bool efivarfs_valid_name(const char *str, int len)55{56 const char *s = str + len - EFI_VARIABLE_GUID_LEN;57 58 /*59 * We need a GUID, plus at least one letter for the variable name,60 * plus the '-' separator61 */62 if (len < EFI_VARIABLE_GUID_LEN + 2)63 return false;64 65 /* GUID must be preceded by a '-' */66 if (*(s - 1) != '-')67 return false;68 69 /*70 * Validate that 's' is of the correct format, e.g.71 *72 * 12345678-1234-1234-1234-123456789abc73 */74 return uuid_is_valid(s);75}76 77static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,78 struct dentry *dentry, umode_t mode, bool excl)79{80 struct efivarfs_fs_info *info = dir->i_sb->s_fs_info;81 struct inode *inode = NULL;82 struct efivar_entry *var;83 int namelen, i = 0, err = 0;84 bool is_removable = false;85 86 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))87 return -EINVAL;88 89 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);90 if (!var)91 return -ENOMEM;92 93 /* length of the variable name itself: remove GUID and separator */94 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;95 96 err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid);97 if (err)98 goto out;99 if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) {100 err = -EPERM;101 goto out;102 }103 104 if (efivar_variable_is_removable(var->var.VendorGuid,105 dentry->d_name.name, namelen))106 is_removable = true;107 108 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);109 if (!inode) {110 err = -ENOMEM;111 goto out;112 }113 114 for (i = 0; i < namelen; i++)115 var->var.VariableName[i] = dentry->d_name.name[i];116 117 var->var.VariableName[i] = '\0';118 119 inode->i_private = var;120 kmemleak_ignore(var);121 122 err = efivar_entry_add(var, &info->efivarfs_list);123 if (err)124 goto out;125 126 d_instantiate(dentry, inode);127 dget(dentry);128out:129 if (err) {130 kfree(var);131 if (inode)132 iput(inode);133 }134 return err;135}136 137static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)138{139 struct efivar_entry *var = d_inode(dentry)->i_private;140 141 if (efivar_entry_delete(var))142 return -EINVAL;143 144 drop_nlink(d_inode(dentry));145 dput(dentry);146 return 0;147};148 149const struct inode_operations efivarfs_dir_inode_operations = {150 .lookup = simple_lookup,151 .unlink = efivarfs_unlink,152 .create = efivarfs_create,153};154 155static int156efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)157{158 unsigned int i_flags;159 unsigned int flags = 0;160 161 i_flags = d_inode(dentry)->i_flags;162 if (i_flags & S_IMMUTABLE)163 flags |= FS_IMMUTABLE_FL;164 165 fileattr_fill_flags(fa, flags);166 167 return 0;168}169 170static int171efivarfs_fileattr_set(struct mnt_idmap *idmap,172 struct dentry *dentry, struct fileattr *fa)173{174 unsigned int i_flags = 0;175 176 if (fileattr_has_fsx(fa))177 return -EOPNOTSUPP;178 179 if (fa->flags & ~FS_IMMUTABLE_FL)180 return -EOPNOTSUPP;181 182 if (fa->flags & FS_IMMUTABLE_FL)183 i_flags |= S_IMMUTABLE;184 185 inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE);186 187 return 0;188}189 190static const struct inode_operations efivarfs_file_inode_operations = {191 .fileattr_get = efivarfs_fileattr_get,192 .fileattr_set = efivarfs_fileattr_set,193};194