linux/fs/sysv/namei.c
Christian Brauner 549c729771
fs: make helpers idmap mount aware
Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24 14:27:20 +01:00

279 lines
5.7 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/sysv/namei.c
*
* minix/namei.c
* Copyright (C) 1991, 1992 Linus Torvalds
*
* coh/namei.c
* Copyright (C) 1993 Pascal Haible, Bruno Haible
*
* sysv/namei.c
* Copyright (C) 1993 Bruno Haible
* Copyright (C) 1997, 1998 Krzysztof G. Baranowski
*/
#include <linux/pagemap.h>
#include "sysv.h"
static int add_nondir(struct dentry *dentry, struct inode *inode)
{
int err = sysv_add_link(dentry, inode);
if (!err) {
d_instantiate(dentry, inode);
return 0;
}
inode_dec_link_count(inode);
iput(inode);
return err;
}
static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
{
struct inode * inode = NULL;
ino_t ino;
if (dentry->d_name.len > SYSV_NAMELEN)
return ERR_PTR(-ENAMETOOLONG);
ino = sysv_inode_by_name(dentry);
if (ino)
inode = sysv_iget(dir->i_sb, ino);
return d_splice_alias(inode, dentry);
}
static int sysv_mknod(struct user_namespace *mnt_userns, struct inode *dir,
struct dentry *dentry, umode_t mode, dev_t rdev)
{
struct inode * inode;
int err;
if (!old_valid_dev(rdev))
return -EINVAL;
inode = sysv_new_inode(dir, mode);
err = PTR_ERR(inode);
if (!IS_ERR(inode)) {
sysv_set_inode(inode, rdev);
mark_inode_dirty(inode);
err = add_nondir(dentry, inode);
}
return err;
}
static int sysv_create(struct user_namespace *mnt_userns, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
return sysv_mknod(&init_user_ns, dir, dentry, mode, 0);
}
static int sysv_symlink(struct user_namespace *mnt_userns, struct inode *dir,
struct dentry *dentry, const char *symname)
{
int err = -ENAMETOOLONG;
int l = strlen(symname)+1;
struct inode * inode;
if (l > dir->i_sb->s_blocksize)
goto out;
inode = sysv_new_inode(dir, S_IFLNK|0777);
err = PTR_ERR(inode);
if (IS_ERR(inode))
goto out;
sysv_set_inode(inode, 0);
err = page_symlink(inode, symname, l);
if (err)
goto out_fail;
mark_inode_dirty(inode);
err = add_nondir(dentry, inode);
out:
return err;
out_fail:
inode_dec_link_count(inode);
iput(inode);
goto out;
}
static int sysv_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 sysv_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
struct dentry *dentry, umode_t mode)
{
struct inode * inode;
int err;
inode_inc_link_count(dir);
inode = sysv_new_inode(dir, S_IFDIR|mode);
err = PTR_ERR(inode);
if (IS_ERR(inode))
goto out_dir;
sysv_set_inode(inode, 0);
inode_inc_link_count(inode);
err = sysv_make_empty(inode, dir);
if (err)
goto out_fail;
err = sysv_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 sysv_unlink(struct inode * dir, struct dentry * dentry)
{
struct inode * inode = d_inode(dentry);
struct page * page;
struct sysv_dir_entry * de;
int err = -ENOENT;
de = sysv_find_entry(dentry, &page);
if (!de)
goto out;
err = sysv_delete_entry (de, page);
if (err)
goto out;
inode->i_ctime = dir->i_ctime;
inode_dec_link_count(inode);
out:
return err;
}
static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
{
struct inode *inode = d_inode(dentry);
int err = -ENOTEMPTY;
if (sysv_empty_dir(inode)) {
err = sysv_unlink(dir, dentry);
if (!err) {
inode->i_size = 0;
inode_dec_link_count(inode);
inode_dec_link_count(dir);
}
}
return err;
}
/*
* Anybody can rename anything with this: the permission checks are left to the
* higher-level routines.
*/
static int sysv_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 sysv_dir_entry * dir_de = NULL;
struct page * old_page;
struct sysv_dir_entry * old_de;
int err = -ENOENT;
if (flags & ~RENAME_NOREPLACE)
return -EINVAL;
old_de = sysv_find_entry(old_dentry, &old_page);
if (!old_de)
goto out;
if (S_ISDIR(old_inode->i_mode)) {
err = -EIO;
dir_de = sysv_dotdot(old_inode, &dir_page);
if (!dir_de)
goto out_old;
}
if (new_inode) {
struct page * new_page;
struct sysv_dir_entry * new_de;
err = -ENOTEMPTY;
if (dir_de && !sysv_empty_dir(new_inode))
goto out_dir;
err = -ENOENT;
new_de = sysv_find_entry(new_dentry, &new_page);
if (!new_de)
goto out_dir;
sysv_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 = sysv_add_link(new_dentry, old_inode);
if (err)
goto out_dir;
if (dir_de)
inode_inc_link_count(new_dir);
}
sysv_delete_entry(old_de, old_page);
mark_inode_dirty(old_inode);
if (dir_de) {
sysv_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 sysv_dir_inode_operations = {
.create = sysv_create,
.lookup = sysv_lookup,
.link = sysv_link,
.unlink = sysv_unlink,
.symlink = sysv_symlink,
.mkdir = sysv_mkdir,
.rmdir = sysv_rmdir,
.mknod = sysv_mknod,
.rename = sysv_rename,
.getattr = sysv_getattr,
};