linux/fs/efivarfs/inode.c
Christian Brauner 8782a9aea3
fs: port ->fileattr_set() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:27 +01:00

189 lines
4.1 KiB
C

// 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,
};