linux-next/fs/minix/namei.c
Christian Brauner 5ebb29bee8
fs: port ->mknod() 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 09:24:26 +01:00

276 lines
5.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/minix/namei.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include "minix.h"
static int add_nondir(struct dentry *dentry, struct inode *inode)
{
int err = minix_add_link(dentry, inode);
if (!err) {
d_instantiate(dentry, inode);
return 0;
}
inode_dec_link_count(inode);
iput(inode);
return err;
}
static struct dentry *minix_lookup(struct inode * dir, struct dentry *dentry, unsigned int flags)
{
struct inode * inode = NULL;
ino_t ino;
if (dentry->d_name.len > minix_sb(dir->i_sb)->s_namelen)
return ERR_PTR(-ENAMETOOLONG);
ino = minix_inode_by_name(dentry);
if (ino)
inode = minix_iget(dir->i_sb, ino);
return d_splice_alias(inode, dentry);
}
static int minix_mknod(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, dev_t rdev)
{
int error;
struct inode *inode;
if (!old_valid_dev(rdev))
return -EINVAL;
inode = minix_new_inode(dir, mode, &error);
if (inode) {
minix_set_inode(inode, rdev);
mark_inode_dirty(inode);
error = add_nondir(dentry, inode);
}
return error;
}
static int minix_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
struct file *file, umode_t mode)
{
int error;
struct inode *inode = minix_new_inode(dir, mode, &error);
if (inode) {
minix_set_inode(inode, 0);
mark_inode_dirty(inode);
d_tmpfile(file, inode);
}
return finish_open_simple(file, error);
}
static int minix_create(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
return minix_mknod(&nop_mnt_idmap, dir, dentry, mode, 0);
}
static int minix_symlink(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, const char *symname)
{
int err = -ENAMETOOLONG;
int i = strlen(symname)+1;
struct inode * inode;
if (i > dir->i_sb->s_blocksize)
goto out;
inode = minix_new_inode(dir, S_IFLNK | 0777, &err);
if (!inode)
goto out;
minix_set_inode(inode, 0);
err = page_symlink(inode, symname, i);
if (err)
goto out_fail;
err = add_nondir(dentry, inode);
out:
return err;
out_fail:
inode_dec_link_count(inode);
iput(inode);
goto out;
}
static int minix_link(struct dentry * old_dentry, struct inode * dir,
struct dentry *dentry)
{
struct inode *inode = d_inode(old_dentry);
inode->i_ctime = current_time(inode);
inode_inc_link_count(inode);
ihold(inode);
return add_nondir(dentry, inode);
}
static int minix_mkdir(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode)
{
struct inode * inode;
int err;
inode_inc_link_count(dir);
inode = minix_new_inode(dir, S_IFDIR | mode, &err);
if (!inode)
goto out_dir;
minix_set_inode(inode, 0);
inode_inc_link_count(inode);
err = minix_make_empty(inode, dir);
if (err)
goto out_fail;
err = minix_add_link(dentry, inode);
if (err)
goto out_fail;
d_instantiate(dentry, inode);
out:
return err;
out_fail:
inode_dec_link_count(inode);
inode_dec_link_count(inode);
iput(inode);
out_dir:
inode_dec_link_count(dir);
goto out;
}
static int minix_unlink(struct inode * dir, struct dentry *dentry)
{
int err = -ENOENT;
struct inode * inode = d_inode(dentry);
struct page * page;
struct minix_dir_entry * de;
de = minix_find_entry(dentry, &page);
if (!de)
goto end_unlink;
err = minix_delete_entry(de, page);
if (err)
goto end_unlink;
inode->i_ctime = dir->i_ctime;
inode_dec_link_count(inode);
end_unlink:
return err;
}
static int minix_rmdir(struct inode * dir, struct dentry *dentry)
{
struct inode * inode = d_inode(dentry);
int err = -ENOTEMPTY;
if (minix_empty_dir(inode)) {
err = minix_unlink(dir, dentry);
if (!err) {
inode_dec_link_count(dir);
inode_dec_link_count(inode);
}
}
return err;
}
static int minix_rename(struct user_namespace *mnt_userns,
struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
struct inode * old_inode = d_inode(old_dentry);
struct inode * new_inode = d_inode(new_dentry);
struct page * dir_page = NULL;
struct minix_dir_entry * dir_de = NULL;
struct page * old_page;
struct minix_dir_entry * old_de;
int err = -ENOENT;
if (flags & ~RENAME_NOREPLACE)
return -EINVAL;
old_de = minix_find_entry(old_dentry, &old_page);
if (!old_de)
goto out;
if (S_ISDIR(old_inode->i_mode)) {
err = -EIO;
dir_de = minix_dotdot(old_inode, &dir_page);
if (!dir_de)
goto out_old;
}
if (new_inode) {
struct page * new_page;
struct minix_dir_entry * new_de;
err = -ENOTEMPTY;
if (dir_de && !minix_empty_dir(new_inode))
goto out_dir;
err = -ENOENT;
new_de = minix_find_entry(new_dentry, &new_page);
if (!new_de)
goto out_dir;
minix_set_link(new_de, new_page, old_inode);
new_inode->i_ctime = current_time(new_inode);
if (dir_de)
drop_nlink(new_inode);
inode_dec_link_count(new_inode);
} else {
err = minix_add_link(new_dentry, old_inode);
if (err)
goto out_dir;
if (dir_de)
inode_inc_link_count(new_dir);
}
minix_delete_entry(old_de, old_page);
mark_inode_dirty(old_inode);
if (dir_de) {
minix_set_link(dir_de, dir_page, new_dir);
inode_dec_link_count(old_dir);
}
return 0;
out_dir:
if (dir_de) {
kunmap(dir_page);
put_page(dir_page);
}
out_old:
kunmap(old_page);
put_page(old_page);
out:
return err;
}
/*
* directories can handle most operations...
*/
const struct inode_operations minix_dir_inode_operations = {
.create = minix_create,
.lookup = minix_lookup,
.link = minix_link,
.unlink = minix_unlink,
.symlink = minix_symlink,
.mkdir = minix_mkdir,
.rmdir = minix_rmdir,
.mknod = minix_mknod,
.rename = minix_rename,
.getattr = minix_getattr,
.tmpfile = minix_tmpfile,
};