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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 Red Hat, Inc.
* Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
*/
#include <linux/efi.h>
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/kmemleak.h>
#include <linux/slab.h>
#include <linux/uuid.h>
#include <linux/fileattr.h>
#include "internal.h"
static const struct inode_operations efivarfs_file_inode_operations;
struct inode *efivarfs_get_inode(struct super_block *sb,
const struct inode *dir, int mode,
dev_t dev, bool is_removable)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
switch (mode & S_IFMT) {
case S_IFREG:
inode->i_op = &efivarfs_file_inode_operations;
inode->i_fop = &efivarfs_file_operations;
break;
case S_IFDIR:
inode->i_op = &efivarfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inc_nlink(inode);
break;
}
}
return inode;
}
/*
* Return true if 'str' is a valid efivarfs filename of the form,
*
* VariableName-12345678-1234-1234-1234-1234567891bc
*/
bool efivarfs_valid_name(const char *str, int len)
{
const char *s = str + len - EFI_VARIABLE_GUID_LEN;
/*
* We need a GUID, plus at least one letter for the variable name,
* plus the '-' separator
*/
if (len < EFI_VARIABLE_GUID_LEN + 2)
return false;
/* GUID must be preceded by a '-' */
if (*(s - 1) != '-')
return false;
/*
* Validate that 's' is of the correct format, e.g.
*
* 12345678-1234-1234-1234-123456789abc
*/
return uuid_is_valid(s);
}
static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
struct inode *inode = NULL;
struct efivar_entry *var;
int namelen, i = 0, err = 0;
bool is_removable = false;
if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
return -EINVAL;
var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
if (!var)
return -ENOMEM;
/* length of the variable name itself: remove GUID and separator */
namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid);
if (err)
goto out;
if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) {
err = -EPERM;
goto out;
}
if (efivar_variable_is_removable(var->var.VendorGuid,
dentry->d_name.name, namelen))
is_removable = true;
inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
if (!inode) {
err = -ENOMEM;
goto out;
}
for (i = 0; i < namelen; i++)
var->var.VariableName[i] = dentry->d_name.name[i];
var->var.VariableName[i] = '\0';
inode->i_private = var;
kmemleak_ignore(var);
err = efivar_entry_add(var, &efivarfs_list);
if (err)
goto out;
d_instantiate(dentry, inode);
dget(dentry);
out:
if (err) {
kfree(var);
if (inode)
iput(inode);
}
return err;
}
static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
{
struct efivar_entry *var = d_inode(dentry)->i_private;
if (efivar_entry_delete(var))
return -EINVAL;
drop_nlink(d_inode(dentry));
dput(dentry);
return 0;
};
const struct inode_operations efivarfs_dir_inode_operations = {
.lookup = simple_lookup,
.unlink = efivarfs_unlink,
.create = efivarfs_create,
};
static int
efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
unsigned int i_flags;
unsigned int flags = 0;
i_flags = d_inode(dentry)->i_flags;
if (i_flags & S_IMMUTABLE)
flags |= FS_IMMUTABLE_FL;
fileattr_fill_flags(fa, flags);
return 0;
}
static int
efivarfs_fileattr_set(struct mnt_idmap *idmap,
struct dentry *dentry, struct fileattr *fa)
{
unsigned int i_flags = 0;
if (fileattr_has_fsx(fa))
return -EOPNOTSUPP;
if (fa->flags & ~FS_IMMUTABLE_FL)
return -EOPNOTSUPP;
if (fa->flags & FS_IMMUTABLE_FL)
i_flags |= S_IMMUTABLE;
inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE);
return 0;
}
static const struct inode_operations efivarfs_file_inode_operations = {
.fileattr_get = efivarfs_fileattr_get,
.fileattr_set = efivarfs_fileattr_set,
};
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