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linux/fs/overlayfs/dir.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
*
* Copyright (C) 2011 Novell Inc.
*/
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/cred.h>
#include <linux/module.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/atomic.h>
#include <linux/ratelimit.h>
#include <linux/backing-file.h>
#include "overlayfs.h"
static unsigned short ovl_redirect_max = 256;
module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
MODULE_PARM_DESC(redirect_max,
"Maximum length of absolute redirect xattr value");
static int ovl_set_redirect(struct dentry *dentry, bool samedir);
static int ovl_cleanup_locked(struct ovl_fs *ofs, struct inode *wdir,
struct dentry *wdentry)
{
int err;
dget(wdentry);
if (d_is_dir(wdentry))
err = ovl_do_rmdir(ofs, wdir, wdentry);
else
err = ovl_do_unlink(ofs, wdir, wdentry);
dput(wdentry);
if (err) {
pr_err("cleanup of '%pd2' failed (%i)\n",
wdentry, err);
}
return err;
}
int ovl_cleanup(struct ovl_fs *ofs, struct dentry *workdir,
struct dentry *wdentry)
{
wdentry = start_removing_dentry(workdir, wdentry);
if (IS_ERR(wdentry))
return PTR_ERR(wdentry);
ovl_cleanup_locked(ofs, workdir->d_inode, wdentry);
end_removing(wdentry);
return 0;
}
void ovl_tempname(char name[OVL_TEMPNAME_SIZE])
{
static atomic_t temp_id = ATOMIC_INIT(0);
/* counter is allowed to wrap, since temp dentries are ephemeral */
snprintf(name, OVL_TEMPNAME_SIZE, "#%x", atomic_inc_return(&temp_id));
}
static struct dentry *ovl_start_creating_temp(struct ovl_fs *ofs,
struct dentry *workdir)
{
char name[OVL_TEMPNAME_SIZE];
ovl_tempname(name);
return start_creating(ovl_upper_mnt_idmap(ofs), workdir,
&QSTR(name));
}
static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
{
int err;
struct dentry *whiteout, *link;
struct dentry *workdir = ofs->workdir;
struct inode *wdir = workdir->d_inode;
guard(mutex)(&ofs->whiteout_lock);
if (!ofs->whiteout) {
whiteout = ovl_start_creating_temp(ofs, workdir);
if (IS_ERR(whiteout))
return whiteout;
err = ovl_do_whiteout(ofs, wdir, whiteout);
if (!err)
ofs->whiteout = dget(whiteout);
end_creating(whiteout);
if (err)
return ERR_PTR(err);
}
if (!ofs->no_shared_whiteout) {
link = ovl_start_creating_temp(ofs, workdir);
if (IS_ERR(link))
return link;
err = ovl_do_link(ofs, ofs->whiteout, wdir, link);
if (!err)
whiteout = dget(link);
end_creating(link);
if (!err)
return whiteout;
if (err != -EMLINK) {
pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%u)\n",
ofs->whiteout->d_inode->i_nlink,
err);
ofs->no_shared_whiteout = true;
}
}
whiteout = ofs->whiteout;
ofs->whiteout = NULL;
return whiteout;
}
int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct dentry *dir,
struct dentry *dentry)
{
struct dentry *whiteout;
struct renamedata rd = {};
int err;
int flags = 0;
whiteout = ovl_whiteout(ofs);
err = PTR_ERR(whiteout);
if (IS_ERR(whiteout))
return err;
if (d_is_dir(dentry))
flags = RENAME_EXCHANGE;
rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
rd.old_parent = ofs->workdir;
rd.new_parent = dir;
rd.flags = flags;
err = start_renaming_two_dentries(&rd, whiteout, dentry);
if (!err) {
err = ovl_do_rename_rd(&rd);
end_renaming(&rd);
}
if (err)
goto kill_whiteout;
if (flags)
ovl_cleanup(ofs, ofs->workdir, dentry);
out:
dput(whiteout);
return err;
kill_whiteout:
ovl_cleanup(ofs, ofs->workdir, whiteout);
goto out;
}
struct dentry *ovl_create_real(struct ovl_fs *ofs, struct dentry *parent,
struct dentry *newdentry, struct ovl_cattr *attr)
{
struct inode *dir = parent->d_inode;
int err;
if (IS_ERR(newdentry))
return newdentry;
err = -ESTALE;
if (newdentry->d_inode)
goto out;
if (attr->hardlink) {
err = ovl_do_link(ofs, attr->hardlink, dir, newdentry);
} else {
switch (attr->mode & S_IFMT) {
case S_IFREG:
err = ovl_do_create(ofs, dir, newdentry, attr->mode);
break;
case S_IFDIR:
/* mkdir is special... */
newdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode);
err = PTR_ERR_OR_ZERO(newdentry);
/* expect to inherit casefolding from workdir/upperdir */
if (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) {
pr_warn_ratelimited("wrong inherited casefold (%pd2)\n",
newdentry);
end_creating(newdentry);
err = -EINVAL;
}
break;
case S_IFCHR:
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
err = ovl_do_mknod(ofs, dir, newdentry, attr->mode,
attr->rdev);
break;
case S_IFLNK:
err = ovl_do_symlink(ofs, dir, newdentry, attr->link);
break;
default:
err = -EPERM;
}
}
if (err)
goto out;
if (WARN_ON(!newdentry->d_inode)) {
/*
* Not quite sure if non-instantiated dentry is legal or not.
* VFS doesn't seem to care so check and warn here.
*/
err = -EIO;
} else if (d_unhashed(newdentry)) {
struct dentry *d;
/*
* Some filesystems (i.e. casefolded) may return an unhashed
* negative dentry from the ovl_lookup_upper() call before
* ovl_create_real().
* In that case, lookup again after making the newdentry
* positive, so ovl_create_upper() always returns a hashed
* positive dentry.
*/
d = ovl_lookup_upper(ofs, newdentry->d_name.name, parent,
newdentry->d_name.len);
dput(newdentry);
if (IS_ERR_OR_NULL(d))
err = d ? PTR_ERR(d) : -ENOENT;
else
return d;
}
out:
if (err) {
end_creating(newdentry);
return ERR_PTR(err);
}
return newdentry;
}
struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir,
struct ovl_cattr *attr)
{
struct dentry *ret;
ret = ovl_start_creating_temp(ofs, workdir);
if (IS_ERR(ret))
return ret;
ret = ovl_create_real(ofs, workdir, ret, attr);
return end_creating_keep(ret);
}
static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
int xerr)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
int err;
err = ovl_check_setxattr(ofs, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
if (!err)
ovl_dentry_set_opaque(dentry);
return err;
}
static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
{
/*
* Fail with -EIO when trying to create opaque dir and upper doesn't
* support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
* return a specific error for noxattr case.
*/
return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
}
/*
* Common operations required to be done after creation of file on upper.
* If @hardlink is false, then @inode is a pre-allocated inode, we may or
* may not use to instantiate the new dentry.
*/
static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
struct dentry *newdentry, bool hardlink, struct file *tmpfile)
{
struct ovl_inode_params oip = {
.upperdentry = newdentry,
.newinode = inode,
};
ovl_dentry_set_upper_alias(dentry);
ovl_dentry_init_reval(dentry, newdentry, NULL);
if (!hardlink) {
/*
* ovl_obtain_alias() can be called after ovl_create_real()
* and before we get here, so we may get an inode from cache
* with the same real upperdentry that is not the inode we
* pre-allocated. In this case we will use the cached inode
* to instantiate the new dentry.
*
* XXX: if we ever use ovl_obtain_alias() to decode directory
* file handles, need to use ovl_get_inode_locked() and
* d_instantiate_new() here to prevent from creating two
* hashed directory inode aliases. We then need to return
* the obtained alias to ovl_mkdir().
*/
inode = ovl_get_inode(dentry->d_sb, &oip);
if (IS_ERR(inode))
return PTR_ERR(inode);
if (inode == oip.newinode)
ovl_set_flag(OVL_UPPERDATA, inode);
} else {
WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
dput(newdentry);
inc_nlink(inode);
}
if (tmpfile)
d_mark_tmpfile(tmpfile, inode);
d_instantiate(dentry, inode);
if (inode != oip.newinode) {
pr_warn_ratelimited("newly created inode found in cache (%pd2)\n",
dentry);
}
/* Force lookup of new upper hardlink to find its lower */
if (hardlink)
d_drop(dentry);
return 0;
}
static bool ovl_type_merge(struct dentry *dentry)
{
return OVL_TYPE_MERGE(ovl_path_type(dentry));
}
static bool ovl_type_origin(struct dentry *dentry)
{
return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
}
static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
struct ovl_cattr *attr)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct dentry *newdentry;
int err;
newdentry = ovl_start_creating_upper(ofs, upperdir,
&QSTR_LEN(dentry->d_name.name,
dentry->d_name.len));
if (IS_ERR(newdentry))
return PTR_ERR(newdentry);
newdentry = ovl_create_real(ofs, upperdir, newdentry, attr);
if (IS_ERR(newdentry))
return PTR_ERR(newdentry);
end_creating_keep(newdentry);
if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) &&
!ovl_allow_offline_changes(ofs)) {
/* Setting opaque here is just an optimization, allow to fail */
ovl_set_opaque(dentry, newdentry);
}
ovl_dir_modified(dentry->d_parent, false);
err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink, NULL);
if (err)
goto out_cleanup;
return 0;
out_cleanup:
ovl_cleanup(ofs, upperdir, newdentry);
dput(newdentry);
return err;
}
static struct dentry *ovl_clear_empty(struct dentry *dentry,
struct list_head *list)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *workdir = ovl_workdir(dentry);
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct renamedata rd = {};
struct path upperpath;
struct dentry *upper;
struct dentry *opaquedir;
struct kstat stat;
int err;
if (WARN_ON(!workdir))
return ERR_PTR(-EROFS);
ovl_path_upper(dentry, &upperpath);
err = vfs_getattr(&upperpath, &stat,
STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
if (err)
goto out;
err = -ESTALE;
if (!S_ISDIR(stat.mode))
goto out;
upper = upperpath.dentry;
opaquedir = ovl_create_temp(ofs, workdir, OVL_CATTR(stat.mode));
err = PTR_ERR(opaquedir);
if (IS_ERR(opaquedir))
goto out;
rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
rd.old_parent = workdir;
rd.new_parent = upperdir;
rd.flags = RENAME_EXCHANGE;
err = start_renaming_two_dentries(&rd, opaquedir, upper);
if (err)
goto out_cleanup_unlocked;
err = ovl_copy_xattr(dentry->d_sb, &upperpath, opaquedir);
if (err)
goto out_cleanup;
err = ovl_set_opaque(dentry, opaquedir);
if (err)
goto out_cleanup;
inode_lock(opaquedir->d_inode);
err = ovl_set_attr(ofs, opaquedir, &stat);
inode_unlock(opaquedir->d_inode);
if (err)
goto out_cleanup;
err = ovl_do_rename_rd(&rd);
end_renaming(&rd);
if (err)
goto out_cleanup_unlocked;
ovl_cleanup_whiteouts(ofs, upper, list);
ovl_cleanup(ofs, workdir, upper);
/* dentry's upper doesn't match now, get rid of it */
d_drop(dentry);
return opaquedir;
out_cleanup:
end_renaming(&rd);
out_cleanup_unlocked:
ovl_cleanup(ofs, workdir, opaquedir);
dput(opaquedir);
out:
return ERR_PTR(err);
}
static int ovl_set_upper_acl(struct ovl_fs *ofs, struct dentry *upperdentry,
const char *acl_name, struct posix_acl *acl)
{
if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
return 0;
return ovl_do_set_acl(ofs, upperdentry, acl_name, acl);
}
static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
struct ovl_cattr *cattr)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *workdir = ovl_workdir(dentry);
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct renamedata rd = {};
struct dentry *upper;
struct dentry *newdentry;
int err;
struct posix_acl *acl, *default_acl;
bool hardlink = !!cattr->hardlink;
if (WARN_ON(!workdir))
return -EROFS;
if (!hardlink) {
err = posix_acl_create(dentry->d_parent->d_inode,
&cattr->mode, &default_acl, &acl);
if (err)
return err;
}
upper = ovl_lookup_upper_unlocked(ofs, dentry->d_name.name, upperdir,
dentry->d_name.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto out;
err = -ESTALE;
if (d_is_negative(upper) || !ovl_upper_is_whiteout(ofs, upper))
goto out_dput;
newdentry = ovl_create_temp(ofs, workdir, cattr);
err = PTR_ERR(newdentry);
if (IS_ERR(newdentry))
goto out_dput;
rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
rd.old_parent = workdir;
rd.new_parent = upperdir;
rd.flags = 0;
err = start_renaming_two_dentries(&rd, newdentry, upper);
if (err)
goto out_cleanup_unlocked;
/*
* mode could have been mutilated due to umask (e.g. sgid directory)
*/
if (!hardlink &&
!S_ISLNK(cattr->mode) &&
newdentry->d_inode->i_mode != cattr->mode) {
struct iattr attr = {
.ia_valid = ATTR_MODE,
.ia_mode = cattr->mode,
};
inode_lock(newdentry->d_inode);
err = ovl_do_notify_change(ofs, newdentry, &attr);
inode_unlock(newdentry->d_inode);
if (err)
goto out_cleanup;
}
if (!hardlink) {
err = ovl_set_upper_acl(ofs, newdentry,
XATTR_NAME_POSIX_ACL_ACCESS, acl);
if (err)
goto out_cleanup;
err = ovl_set_upper_acl(ofs, newdentry,
XATTR_NAME_POSIX_ACL_DEFAULT, default_acl);
if (err)
goto out_cleanup;
}
if (!hardlink && S_ISDIR(cattr->mode)) {
err = ovl_set_opaque(dentry, newdentry);
if (err)
goto out_cleanup;
rd.flags = RENAME_EXCHANGE;
err = ovl_do_rename_rd(&rd);
end_renaming(&rd);
if (err)
goto out_cleanup_unlocked;
ovl_cleanup(ofs, workdir, upper);
} else {
err = ovl_do_rename_rd(&rd);
end_renaming(&rd);
if (err)
goto out_cleanup_unlocked;
}
ovl_dir_modified(dentry->d_parent, false);
err = ovl_instantiate(dentry, inode, newdentry, hardlink, NULL);
if (err) {
ovl_cleanup(ofs, upperdir, newdentry);
dput(newdentry);
}
out_dput:
dput(upper);
out:
if (!hardlink) {
posix_acl_release(acl);
posix_acl_release(default_acl);
}
return err;
out_cleanup:
end_renaming(&rd);
out_cleanup_unlocked:
ovl_cleanup(ofs, workdir, newdentry);
dput(newdentry);
goto out_dput;
}
static const struct cred *ovl_override_creator_creds(const struct cred *original_creds,
struct dentry *dentry, struct inode *inode, umode_t mode)
{
int err;
if (WARN_ON_ONCE(current->cred != ovl_creds(dentry->d_sb)))
return ERR_PTR(-EINVAL);
CLASS(prepare_creds, override_cred)();
if (!override_cred)
return ERR_PTR(-ENOMEM);
override_cred->fsuid = inode->i_uid;
override_cred->fsgid = inode->i_gid;
err = security_dentry_create_files_as(dentry, mode, &dentry->d_name,
original_creds, override_cred);
if (err)
return ERR_PTR(err);
return override_creds(no_free_ptr(override_cred));
}
static void ovl_revert_creator_creds(const struct cred *old_cred)
{
const struct cred *override_cred;
override_cred = revert_creds(old_cred);
put_cred(override_cred);
}
DEFINE_CLASS(ovl_override_creator_creds,
const struct cred *,
if (!IS_ERR_OR_NULL(_T)) ovl_revert_creator_creds(_T),
ovl_override_creator_creds(original_creds, dentry, inode, mode),
const struct cred *original_creds,
struct dentry *dentry,
struct inode *inode,
umode_t mode)
static int ovl_create_handle_whiteouts(struct dentry *dentry,
struct inode *inode,
struct ovl_cattr *attr)
{
if (!ovl_dentry_is_whiteout(dentry))
return ovl_create_upper(dentry, inode, attr);
return ovl_create_over_whiteout(dentry, inode, attr);
}
static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
struct ovl_cattr *attr, bool origin)
{
int err;
struct dentry *parent = dentry->d_parent;
scoped_class(override_creds_ovl, original_creds, dentry->d_sb) {
/*
* When linking a file with copy up origin into a new parent, mark the
* new parent dir "impure".
*/
if (origin) {
err = ovl_set_impure(parent, ovl_dentry_upper(parent));
if (err)
return err;
}
/*
* In the creation cases(create, mkdir, mknod, symlink),
* ovl should transfer current's fs{u,g}id to underlying
* fs. Because underlying fs want to initialize its new
* inode owner using current's fs{u,g}id. And in this
* case, the @inode is a new inode that is initialized
* in inode_init_owner() to current's fs{u,g}id. So use
* the inode's i_{u,g}id to override the cred's fs{u,g}id.
*
* But in the other hardlink case, ovl_link() does not
* create a new inode, so just use the ovl mounter's
* fs{u,g}id.
*/
if (attr->hardlink)
return ovl_create_handle_whiteouts(dentry, inode, attr);
scoped_class(ovl_override_creator_creds, cred, original_creds, dentry, inode, attr->mode) {
if (IS_ERR(cred))
return PTR_ERR(cred);
return ovl_create_handle_whiteouts(dentry, inode, attr);
}
}
return err;
}
static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
const char *link)
{
int err;
struct inode *inode;
struct ovl_cattr attr = {
.rdev = rdev,
.link = link,
};
err = ovl_copy_up(dentry->d_parent);
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
goto out;
/* Preallocate inode to be used by ovl_get_inode() */
err = -ENOMEM;
inode = ovl_new_inode(dentry->d_sb, mode, rdev);
if (!inode)
goto out_drop_write;
spin_lock(&inode->i_lock);
inode_state_set(inode, I_CREATING);
spin_unlock(&inode->i_lock);
inode_init_owner(&nop_mnt_idmap, inode, dentry->d_parent->d_inode, mode);
attr.mode = inode->i_mode;
err = ovl_create_or_link(dentry, inode, &attr, false);
/* Did we end up using the preallocated inode? */
if (inode != d_inode(dentry))
iput(inode);
out_drop_write:
ovl_drop_write(dentry);
out:
return err;
}
static int ovl_create(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
}
static struct dentry *ovl_mkdir(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode)
{
return ERR_PTR(ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL));
}
static int ovl_mknod(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, dev_t rdev)
{
/* Don't allow creation of "whiteout" on overlay */
if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
return -EPERM;
return ovl_create_object(dentry, mode, rdev, NULL);
}
static int ovl_symlink(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, const char *link)
{
return ovl_create_object(dentry, S_IFLNK, 0, link);
}
static int ovl_set_link_redirect(struct dentry *dentry)
{
with_ovl_creds(dentry->d_sb)
return ovl_set_redirect(dentry, false);
}
static int ovl_link(struct dentry *old, struct inode *newdir,
struct dentry *new)
{
int err;
struct inode *inode;
err = ovl_copy_up(old);
if (err)
goto out;
err = ovl_copy_up(new->d_parent);
if (err)
goto out;
err = ovl_nlink_start(old);
if (err)
goto out;
if (ovl_is_metacopy_dentry(old)) {
err = ovl_set_link_redirect(old);
if (err)
goto out_nlink_end;
}
inode = d_inode(old);
ihold(inode);
err = ovl_create_or_link(new, inode,
&(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)},
ovl_type_origin(old));
if (err)
iput(inode);
out_nlink_end:
ovl_nlink_end(old);
out:
return err;
}
static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
{
return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper);
}
static int ovl_remove_and_whiteout(struct dentry *dentry,
struct list_head *list)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *workdir = ovl_workdir(dentry);
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct dentry *upper;
struct dentry *opaquedir = NULL;
int err;
if (WARN_ON(!workdir))
return -EROFS;
if (!list_empty(list)) {
opaquedir = ovl_clear_empty(dentry, list);
err = PTR_ERR(opaquedir);
if (IS_ERR(opaquedir))
goto out;
}
upper = ovl_lookup_upper_unlocked(ofs, dentry->d_name.name, upperdir,
dentry->d_name.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto out_dput;
err = -ESTALE;
if ((opaquedir && upper != opaquedir) ||
(!opaquedir && ovl_dentry_upper(dentry) &&
!ovl_matches_upper(dentry, upper))) {
goto out_dput_upper;
}
err = ovl_cleanup_and_whiteout(ofs, upperdir, upper);
if (!err)
ovl_dir_modified(dentry->d_parent, true);
d_drop(dentry);
out_dput_upper:
dput(upper);
out_dput:
dput(opaquedir);
out:
return err;
}
static int ovl_remove_upper(struct dentry *dentry, bool is_dir,
struct list_head *list)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct inode *dir = upperdir->d_inode;
struct dentry *upper;
struct dentry *opaquedir = NULL;
int err;
if (!list_empty(list)) {
opaquedir = ovl_clear_empty(dentry, list);
err = PTR_ERR(opaquedir);
if (IS_ERR(opaquedir))
goto out;
}
upper = ovl_start_removing_upper(ofs, upperdir,
&QSTR_LEN(dentry->d_name.name,
dentry->d_name.len));
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto out_dput;
err = -ESTALE;
if ((opaquedir && upper != opaquedir) ||
(!opaquedir && !ovl_matches_upper(dentry, upper)))
goto out_unlock;
if (is_dir)
err = ovl_do_rmdir(ofs, dir, upper);
else
err = ovl_do_unlink(ofs, dir, upper);
ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry));
/*
* Keeping this dentry hashed would mean having to release
* upperpath/lowerpath, which could only be done if we are the
* sole user of this dentry. Too tricky... Just unhash for
* now.
*/
if (!err)
d_drop(dentry);
out_unlock:
end_removing(upper);
out_dput:
dput(opaquedir);
out:
return err;
}
static bool ovl_pure_upper(struct dentry *dentry)
{
return !ovl_dentry_lower(dentry) &&
!ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry));
}
static void ovl_drop_nlink(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct dentry *alias;
/* Try to find another, hashed alias */
spin_lock(&inode->i_lock);
hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
if (alias != dentry && !d_unhashed(alias))
break;
}
spin_unlock(&inode->i_lock);
/*
* Changes to underlying layers may cause i_nlink to lose sync with
* reality. In this case prevent the link count from going to zero
* prematurely.
*/
if (inode->i_nlink > !!alias)
drop_nlink(inode);
}
static int ovl_do_remove(struct dentry *dentry, bool is_dir)
{
int err;
bool lower_positive = ovl_lower_positive(dentry);
LIST_HEAD(list);
/* No need to clean pure upper removed by vfs_rmdir() */
if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) {
err = ovl_check_empty_dir(dentry, &list);
if (err)
goto out;
}
err = ovl_copy_up(dentry->d_parent);
if (err)
goto out;
err = ovl_nlink_start(dentry);
if (err)
goto out;
with_ovl_creds(dentry->d_sb) {
if (!lower_positive)
err = ovl_remove_upper(dentry, is_dir, &list);
else
err = ovl_remove_and_whiteout(dentry, &list);
}
if (!err) {
if (is_dir)
clear_nlink(dentry->d_inode);
else
ovl_drop_nlink(dentry);
}
ovl_nlink_end(dentry);
/*
* Copy ctime
*
* Note: we fail to update ctime if there was no copy-up, only a
* whiteout
*/
if (ovl_dentry_upper(dentry))
ovl_copyattr(d_inode(dentry));
out:
ovl_cache_free(&list);
return err;
}
static int ovl_unlink(struct inode *dir, struct dentry *dentry)
{
return ovl_do_remove(dentry, false);
}
static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
{
return ovl_do_remove(dentry, true);
}
static bool ovl_type_merge_or_lower(struct dentry *dentry)
{
enum ovl_path_type type = ovl_path_type(dentry);
return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type);
}
static bool ovl_can_move(struct dentry *dentry)
{
return ovl_redirect_dir(OVL_FS(dentry->d_sb)) ||
!d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
}
static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect)
{
char *buf, *ret;
struct dentry *d, *tmp;
int buflen = ovl_redirect_max + 1;
if (!abs_redirect) {
ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
GFP_KERNEL);
goto out;
}
buf = ret = kmalloc(buflen, GFP_KERNEL);
if (!buf)
goto out;
buflen--;
buf[buflen] = '\0';
for (d = dget(dentry); !IS_ROOT(d);) {
const char *name;
int thislen;
spin_lock(&d->d_lock);
name = ovl_dentry_get_redirect(d);
if (name) {
thislen = strlen(name);
} else {
name = d->d_name.name;
thislen = d->d_name.len;
}
/* If path is too long, fall back to userspace move */
if (thislen + (name[0] != '/') > buflen) {
ret = ERR_PTR(-EXDEV);
spin_unlock(&d->d_lock);
goto out_put;
}
buflen -= thislen;
memcpy(&buf[buflen], name, thislen);
spin_unlock(&d->d_lock);
tmp = dget_parent(d);
dput(d);
d = tmp;
/* Absolute redirect: finished */
if (buf[buflen] == '/')
break;
buflen--;
buf[buflen] = '/';
}
ret = kstrdup(&buf[buflen], GFP_KERNEL);
out_put:
dput(d);
kfree(buf);
out:
return ret ? ret : ERR_PTR(-ENOMEM);
}
static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir)
{
struct dentry *lowerdentry;
if (!samedir)
return true;
if (d_is_dir(dentry))
return false;
/*
* For non-dir hardlinked files, we need absolute redirects
* in general as two upper hardlinks could be in different
* dirs. We could put a relative redirect now and convert
* it to absolute redirect later. But when nlink > 1 and
* indexing is on, that means relative redirect needs to be
* converted to absolute during copy up of another lower
* hardllink as well.
*
* So without optimizing too much, just check if lower is
* a hard link or not. If lower is hard link, put absolute
* redirect.
*/
lowerdentry = ovl_dentry_lower(dentry);
return (d_inode(lowerdentry)->i_nlink > 1);
}
static int ovl_set_redirect(struct dentry *dentry, bool samedir)
{
int err;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
const char *redirect = ovl_dentry_get_redirect(dentry);
bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir);
if (redirect && (!absolute_redirect || redirect[0] == '/'))
return 0;
redirect = ovl_get_redirect(dentry, absolute_redirect);
if (IS_ERR(redirect))
return PTR_ERR(redirect);
err = ovl_check_setxattr(ofs, ovl_dentry_upper(dentry),
OVL_XATTR_REDIRECT,
redirect, strlen(redirect), -EXDEV);
if (!err) {
spin_lock(&dentry->d_lock);
ovl_dentry_set_redirect(dentry, redirect);
spin_unlock(&dentry->d_lock);
} else {
kfree(redirect);
pr_warn_ratelimited("failed to set redirect (%i)\n",
err);
/* Fall back to userspace copy-up */
err = -EXDEV;
}
return err;
}
struct ovl_renamedata {
struct renamedata;
struct dentry *opaquedir;
bool cleanup_whiteout;
bool update_nlink;
bool overwrite;
};
static int ovl_rename_start(struct ovl_renamedata *ovlrd, struct list_head *list)
{
struct dentry *old = ovlrd->old_dentry;
struct dentry *new = ovlrd->new_dentry;
bool is_dir = d_is_dir(old);
bool new_is_dir = d_is_dir(new);
int err;
if (ovlrd->flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
return -EINVAL;
ovlrd->flags &= ~RENAME_NOREPLACE;
/* Don't copy up directory trees */
err = -EXDEV;
if (!ovl_can_move(old))
return err;
if (!ovlrd->overwrite && !ovl_can_move(new))
return err;
if (ovlrd->overwrite && new_is_dir && !ovl_pure_upper(new)) {
err = ovl_check_empty_dir(new, list);
if (err)
return err;
}
if (ovlrd->overwrite) {
if (ovl_lower_positive(old)) {
if (!ovl_dentry_is_whiteout(new)) {
/* Whiteout source */
ovlrd->flags |= RENAME_WHITEOUT;
} else {
/* Switch whiteouts */
ovlrd->flags |= RENAME_EXCHANGE;
}
} else if (is_dir && ovl_dentry_is_whiteout(new)) {
ovlrd->flags |= RENAME_EXCHANGE;
ovlrd->cleanup_whiteout = true;
}
}
err = ovl_copy_up(old);
if (err)
return err;
err = ovl_copy_up(new->d_parent);
if (err)
return err;
if (!ovlrd->overwrite) {
err = ovl_copy_up(new);
if (err)
return err;
} else if (d_inode(new)) {
err = ovl_nlink_start(new);
if (err)
return err;
ovlrd->update_nlink = true;
}
if (!ovlrd->update_nlink) {
/* ovl_nlink_start() took ovl_want_write() */
err = ovl_want_write(old);
if (err)
return err;
}
return 0;
}
static int ovl_rename_upper(struct ovl_renamedata *ovlrd, struct list_head *list)
{
struct dentry *old = ovlrd->old_dentry;
struct dentry *new = ovlrd->new_dentry;
struct ovl_fs *ofs = OVL_FS(old->d_sb);
struct dentry *old_upperdir = ovl_dentry_upper(old->d_parent);
struct dentry *new_upperdir = ovl_dentry_upper(new->d_parent);
bool is_dir = d_is_dir(old);
bool new_is_dir = d_is_dir(new);
bool samedir = old->d_parent == new->d_parent;
struct renamedata rd = {};
struct dentry *de;
struct dentry *whiteout = NULL;
bool old_opaque, new_opaque;
int err;
if (!list_empty(list)) {
de = ovl_clear_empty(new, list);
if (IS_ERR(de))
return PTR_ERR(de);
ovlrd->opaquedir = de;
}
if (!samedir) {
/*
* When moving a merge dir or non-dir with copy up origin into
* a new parent, we are marking the new parent dir "impure".
* When ovl_iterate() iterates an "impure" upper dir, it will
* lookup the origin inodes of the entries to fill d_ino.
*/
if (ovl_type_origin(old)) {
err = ovl_set_impure(new->d_parent, new_upperdir);
if (err)
return err;
}
if (!ovlrd->overwrite && ovl_type_origin(new)) {
err = ovl_set_impure(old->d_parent, old_upperdir);
if (err)
return err;
}
}
rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
rd.old_parent = old_upperdir;
rd.new_parent = new_upperdir;
rd.flags = ovlrd->flags;
err = start_renaming(&rd, 0,
&QSTR_LEN(old->d_name.name, old->d_name.len),
&QSTR_LEN(new->d_name.name, new->d_name.len));
if (err)
return err;
err = -ESTALE;
if (!ovl_matches_upper(old, rd.old_dentry))
goto out_unlock;
old_opaque = ovl_dentry_is_opaque(old);
new_opaque = ovl_dentry_is_opaque(new);
err = -ESTALE;
if (d_inode(new) && ovl_dentry_upper(new)) {
if (ovlrd->opaquedir) {
if (rd.new_dentry != ovlrd->opaquedir)
goto out_unlock;
} else {
if (!ovl_matches_upper(new, rd.new_dentry))
goto out_unlock;
}
} else {
if (!d_is_negative(rd.new_dentry)) {
if (!new_opaque || !ovl_upper_is_whiteout(ofs, rd.new_dentry))
goto out_unlock;
} else {
if (ovlrd->flags & RENAME_EXCHANGE)
goto out_unlock;
}
}
if (rd.old_dentry->d_inode == rd.new_dentry->d_inode)
goto out_unlock;
err = 0;
if (ovl_type_merge_or_lower(old))
err = ovl_set_redirect(old, samedir);
else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent))
err = ovl_set_opaque_xerr(old, rd.old_dentry, -EXDEV);
if (err)
goto out_unlock;
if (!ovlrd->overwrite && ovl_type_merge_or_lower(new))
err = ovl_set_redirect(new, samedir);
else if (!ovlrd->overwrite && new_is_dir && !new_opaque &&
ovl_type_merge(old->d_parent))
err = ovl_set_opaque_xerr(new, rd.new_dentry, -EXDEV);
if (err)
goto out_unlock;
err = ovl_do_rename_rd(&rd);
if (!err && ovlrd->cleanup_whiteout)
whiteout = dget(rd.new_dentry);
out_unlock:
end_renaming(&rd);
if (err)
return err;
if (whiteout) {
ovl_cleanup(ofs, old_upperdir, whiteout);
dput(whiteout);
}
if (ovlrd->overwrite && d_inode(new)) {
if (new_is_dir)
clear_nlink(d_inode(new));
else
ovl_drop_nlink(new);
}
ovl_dir_modified(old->d_parent, ovl_type_origin(old) ||
(!ovlrd->overwrite && ovl_type_origin(new)));
ovl_dir_modified(new->d_parent, ovl_type_origin(old) ||
(d_inode(new) && ovl_type_origin(new)));
/* copy ctime: */
ovl_copyattr(d_inode(old));
if (d_inode(new) && ovl_dentry_upper(new))
ovl_copyattr(d_inode(new));
return err;
}
static void ovl_rename_end(struct ovl_renamedata *ovlrd)
{
if (ovlrd->update_nlink)
ovl_nlink_end(ovlrd->new_dentry);
else
ovl_drop_write(ovlrd->old_dentry);
}
static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
struct dentry *old, struct inode *newdir,
struct dentry *new, unsigned int flags)
{
struct ovl_renamedata ovlrd = {
.old_parent = old->d_parent,
.old_dentry = old,
.new_parent = new->d_parent,
.new_dentry = new,
.flags = flags,
.overwrite = !(flags & RENAME_EXCHANGE),
};
LIST_HEAD(list);
int err;
err = ovl_rename_start(&ovlrd, &list);
if (!err) {
with_ovl_creds(old->d_sb)
err = ovl_rename_upper(&ovlrd, &list);
ovl_rename_end(&ovlrd);
}
dput(ovlrd.opaquedir);
ovl_cache_free(&list);
return err;
}
static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
struct inode *inode, umode_t mode)
{
struct path realparentpath;
struct file *realfile;
struct ovl_file *of;
struct dentry *newdentry;
/* It's okay to set O_NOATIME, since the owner will be current fsuid */
int flags = file->f_flags | OVL_OPEN_FLAGS;
int err;
scoped_class(override_creds_ovl, original_creds, dentry->d_sb) {
scoped_class(ovl_override_creator_creds, cred, original_creds, dentry, inode, mode) {
if (IS_ERR(cred))
return PTR_ERR(cred);
ovl_path_upper(dentry->d_parent, &realparentpath);
realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath,
mode, current_cred());
err = PTR_ERR_OR_ZERO(realfile);
pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err);
if (err)
return err;
of = ovl_file_alloc(realfile);
if (!of) {
fput(realfile);
return -ENOMEM;
}
/* ovl_instantiate() consumes the newdentry reference on success */
newdentry = dget(realfile->f_path.dentry);
err = ovl_instantiate(dentry, inode, newdentry, false, file);
if (!err) {
file->private_data = of;
} else {
dput(newdentry);
ovl_file_free(of);
}
}
}
return err;
}
static int ovl_dummy_open(struct inode *inode, struct file *file)
{
return 0;
}
static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
struct file *file, umode_t mode)
{
int err;
struct dentry *dentry = file->f_path.dentry;
struct inode *inode;
if (!OVL_FS(dentry->d_sb)->tmpfile)
return -EOPNOTSUPP;
err = ovl_copy_up(dentry->d_parent);
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
return err;
err = -ENOMEM;
inode = ovl_new_inode(dentry->d_sb, mode, 0);
if (!inode)
goto drop_write;
inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
err = ovl_create_tmpfile(file, dentry, inode, inode->i_mode);
if (err)
goto put_inode;
/*
* Check if the preallocated inode was actually used. Having something
* else assigned to the dentry shouldn't happen as that would indicate
* that the backing tmpfile "leaked" out of overlayfs.
*/
err = -EIO;
if (WARN_ON(inode != d_inode(dentry)))
goto put_realfile;
/* inode reference was transferred to dentry */
inode = NULL;
err = finish_open(file, dentry, ovl_dummy_open);
put_realfile:
/* Without FMODE_OPENED ->release() won't be called on @file */
if (!(file->f_mode & FMODE_OPENED))
ovl_file_free(file->private_data);
put_inode:
iput(inode);
drop_write:
ovl_drop_write(dentry);
return err;
}
const struct inode_operations ovl_dir_inode_operations = {
.lookup = ovl_lookup,
.mkdir = ovl_mkdir,
.symlink = ovl_symlink,
.unlink = ovl_unlink,
.rmdir = ovl_rmdir,
.rename = ovl_rename,
.link = ovl_link,
.setattr = ovl_setattr,
.create = ovl_create,
.mknod = ovl_mknod,
.permission = ovl_permission,
.getattr = ovl_getattr,
.listxattr = ovl_listxattr,
.get_inode_acl = ovl_get_inode_acl,
.get_acl = ovl_get_acl,
.set_acl = ovl_set_acl,
.update_time = ovl_update_time,
.fileattr_get = ovl_fileattr_get,
.fileattr_set = ovl_fileattr_set,
.tmpfile = ovl_tmpfile,
};
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