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![Christian Brauner](/assets/img/avatar_default.png)
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>
719 lines
16 KiB
C
719 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2017 Red Hat, Inc.
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*/
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#include <linux/cred.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/xattr.h>
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#include <linux/uio.h>
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#include <linux/uaccess.h>
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#include <linux/splice.h>
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#include <linux/security.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include "overlayfs.h"
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struct ovl_aio_req {
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struct kiocb iocb;
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refcount_t ref;
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struct kiocb *orig_iocb;
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struct fd fd;
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};
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static struct kmem_cache *ovl_aio_request_cachep;
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static char ovl_whatisit(struct inode *inode, struct inode *realinode)
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{
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if (realinode != ovl_inode_upper(inode))
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return 'l';
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if (ovl_has_upperdata(inode))
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return 'u';
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else
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return 'm';
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}
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/* No atime modification nor notify on underlying */
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#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
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static struct file *ovl_open_realfile(const struct file *file,
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const struct path *realpath)
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{
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struct inode *realinode = d_inode(realpath->dentry);
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struct inode *inode = file_inode(file);
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struct mnt_idmap *real_idmap;
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struct file *realfile;
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const struct cred *old_cred;
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int flags = file->f_flags | OVL_OPEN_FLAGS;
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int acc_mode = ACC_MODE(flags);
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int err;
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if (flags & O_APPEND)
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acc_mode |= MAY_APPEND;
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old_cred = ovl_override_creds(inode->i_sb);
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real_idmap = mnt_idmap(realpath->mnt);
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err = inode_permission(real_idmap, realinode, MAY_OPEN | acc_mode);
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if (err) {
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realfile = ERR_PTR(err);
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} else {
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if (!inode_owner_or_capable(real_idmap, realinode))
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flags &= ~O_NOATIME;
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realfile = open_with_fake_path(&file->f_path, flags, realinode,
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current_cred());
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}
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revert_creds(old_cred);
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pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
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file, file, ovl_whatisit(inode, realinode), file->f_flags,
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realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
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return realfile;
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}
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#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
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static int ovl_change_flags(struct file *file, unsigned int flags)
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{
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struct inode *inode = file_inode(file);
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int err;
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flags &= OVL_SETFL_MASK;
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if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
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return -EPERM;
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if ((flags & O_DIRECT) && !(file->f_mode & FMODE_CAN_ODIRECT))
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return -EINVAL;
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if (file->f_op->check_flags) {
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err = file->f_op->check_flags(flags);
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if (err)
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return err;
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}
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spin_lock(&file->f_lock);
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file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
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file->f_iocb_flags = iocb_flags(file);
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spin_unlock(&file->f_lock);
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return 0;
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}
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static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
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bool allow_meta)
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{
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struct dentry *dentry = file_dentry(file);
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struct path realpath;
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real->flags = 0;
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real->file = file->private_data;
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if (allow_meta)
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ovl_path_real(dentry, &realpath);
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else
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ovl_path_realdata(dentry, &realpath);
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/* Has it been copied up since we'd opened it? */
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if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
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real->flags = FDPUT_FPUT;
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real->file = ovl_open_realfile(file, &realpath);
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return PTR_ERR_OR_ZERO(real->file);
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}
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/* Did the flags change since open? */
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if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
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return ovl_change_flags(real->file, file->f_flags);
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return 0;
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}
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static int ovl_real_fdget(const struct file *file, struct fd *real)
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{
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if (d_is_dir(file_dentry(file))) {
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real->flags = 0;
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real->file = ovl_dir_real_file(file, false);
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return PTR_ERR_OR_ZERO(real->file);
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}
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return ovl_real_fdget_meta(file, real, false);
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}
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static int ovl_open(struct inode *inode, struct file *file)
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{
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struct dentry *dentry = file_dentry(file);
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struct file *realfile;
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struct path realpath;
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int err;
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err = ovl_maybe_copy_up(dentry, file->f_flags);
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if (err)
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return err;
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/* No longer need these flags, so don't pass them on to underlying fs */
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file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
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ovl_path_realdata(dentry, &realpath);
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realfile = ovl_open_realfile(file, &realpath);
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if (IS_ERR(realfile))
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return PTR_ERR(realfile);
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file->private_data = realfile;
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return 0;
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}
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static int ovl_release(struct inode *inode, struct file *file)
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{
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fput(file->private_data);
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return 0;
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}
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static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
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{
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struct inode *inode = file_inode(file);
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struct fd real;
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const struct cred *old_cred;
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loff_t ret;
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/*
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* The two special cases below do not need to involve real fs,
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* so we can optimizing concurrent callers.
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*/
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if (offset == 0) {
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if (whence == SEEK_CUR)
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return file->f_pos;
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if (whence == SEEK_SET)
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return vfs_setpos(file, 0, 0);
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}
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ret = ovl_real_fdget(file, &real);
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if (ret)
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return ret;
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/*
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* Overlay file f_pos is the master copy that is preserved
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* through copy up and modified on read/write, but only real
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* fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
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* limitations that are more strict than ->s_maxbytes for specific
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* files, so we use the real file to perform seeks.
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*/
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ovl_inode_lock(inode);
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real.file->f_pos = file->f_pos;
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old_cred = ovl_override_creds(inode->i_sb);
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ret = vfs_llseek(real.file, offset, whence);
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revert_creds(old_cred);
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file->f_pos = real.file->f_pos;
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ovl_inode_unlock(inode);
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fdput(real);
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return ret;
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}
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static void ovl_file_accessed(struct file *file)
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{
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struct inode *inode, *upperinode;
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if (file->f_flags & O_NOATIME)
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return;
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inode = file_inode(file);
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upperinode = ovl_inode_upper(inode);
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if (!upperinode)
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return;
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if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
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!timespec64_equal(&inode->i_ctime, &upperinode->i_ctime))) {
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inode->i_mtime = upperinode->i_mtime;
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inode->i_ctime = upperinode->i_ctime;
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}
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touch_atime(&file->f_path);
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}
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static rwf_t ovl_iocb_to_rwf(int ifl)
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{
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rwf_t flags = 0;
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if (ifl & IOCB_NOWAIT)
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flags |= RWF_NOWAIT;
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if (ifl & IOCB_HIPRI)
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flags |= RWF_HIPRI;
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if (ifl & IOCB_DSYNC)
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flags |= RWF_DSYNC;
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if (ifl & IOCB_SYNC)
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flags |= RWF_SYNC;
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return flags;
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}
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static inline void ovl_aio_put(struct ovl_aio_req *aio_req)
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{
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if (refcount_dec_and_test(&aio_req->ref)) {
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fdput(aio_req->fd);
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kmem_cache_free(ovl_aio_request_cachep, aio_req);
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}
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}
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static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
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{
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struct kiocb *iocb = &aio_req->iocb;
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struct kiocb *orig_iocb = aio_req->orig_iocb;
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if (iocb->ki_flags & IOCB_WRITE) {
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struct inode *inode = file_inode(orig_iocb->ki_filp);
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/* Actually acquired in ovl_write_iter() */
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__sb_writers_acquired(file_inode(iocb->ki_filp)->i_sb,
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SB_FREEZE_WRITE);
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file_end_write(iocb->ki_filp);
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ovl_copyattr(inode);
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}
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orig_iocb->ki_pos = iocb->ki_pos;
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ovl_aio_put(aio_req);
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}
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static void ovl_aio_rw_complete(struct kiocb *iocb, long res)
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{
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struct ovl_aio_req *aio_req = container_of(iocb,
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struct ovl_aio_req, iocb);
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struct kiocb *orig_iocb = aio_req->orig_iocb;
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ovl_aio_cleanup_handler(aio_req);
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orig_iocb->ki_complete(orig_iocb, res);
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}
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static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct file *file = iocb->ki_filp;
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struct fd real;
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const struct cred *old_cred;
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ssize_t ret;
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if (!iov_iter_count(iter))
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return 0;
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ret = ovl_real_fdget(file, &real);
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if (ret)
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return ret;
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ret = -EINVAL;
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if (iocb->ki_flags & IOCB_DIRECT &&
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!(real.file->f_mode & FMODE_CAN_ODIRECT))
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goto out_fdput;
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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if (is_sync_kiocb(iocb)) {
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ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
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ovl_iocb_to_rwf(iocb->ki_flags));
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} else {
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struct ovl_aio_req *aio_req;
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ret = -ENOMEM;
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aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
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if (!aio_req)
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goto out;
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aio_req->fd = real;
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real.flags = 0;
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aio_req->orig_iocb = iocb;
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kiocb_clone(&aio_req->iocb, iocb, real.file);
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aio_req->iocb.ki_complete = ovl_aio_rw_complete;
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refcount_set(&aio_req->ref, 2);
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ret = vfs_iocb_iter_read(real.file, &aio_req->iocb, iter);
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ovl_aio_put(aio_req);
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if (ret != -EIOCBQUEUED)
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ovl_aio_cleanup_handler(aio_req);
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}
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out:
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revert_creds(old_cred);
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ovl_file_accessed(file);
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out_fdput:
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fdput(real);
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return ret;
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}
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static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct file *file = iocb->ki_filp;
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struct inode *inode = file_inode(file);
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struct fd real;
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const struct cred *old_cred;
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ssize_t ret;
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int ifl = iocb->ki_flags;
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if (!iov_iter_count(iter))
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return 0;
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inode_lock(inode);
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/* Update mode */
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ovl_copyattr(inode);
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ret = file_remove_privs(file);
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if (ret)
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goto out_unlock;
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ret = ovl_real_fdget(file, &real);
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if (ret)
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goto out_unlock;
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ret = -EINVAL;
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if (iocb->ki_flags & IOCB_DIRECT &&
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!(real.file->f_mode & FMODE_CAN_ODIRECT))
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goto out_fdput;
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if (!ovl_should_sync(OVL_FS(inode->i_sb)))
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ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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if (is_sync_kiocb(iocb)) {
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file_start_write(real.file);
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ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
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ovl_iocb_to_rwf(ifl));
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file_end_write(real.file);
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/* Update size */
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ovl_copyattr(inode);
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} else {
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struct ovl_aio_req *aio_req;
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|
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ret = -ENOMEM;
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aio_req = kmem_cache_zalloc(ovl_aio_request_cachep, GFP_KERNEL);
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if (!aio_req)
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goto out;
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|
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file_start_write(real.file);
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/* Pacify lockdep, same trick as done in aio_write() */
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__sb_writers_release(file_inode(real.file)->i_sb,
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SB_FREEZE_WRITE);
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aio_req->fd = real;
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real.flags = 0;
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aio_req->orig_iocb = iocb;
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kiocb_clone(&aio_req->iocb, iocb, real.file);
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aio_req->iocb.ki_flags = ifl;
|
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aio_req->iocb.ki_complete = ovl_aio_rw_complete;
|
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refcount_set(&aio_req->ref, 2);
|
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ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter);
|
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ovl_aio_put(aio_req);
|
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if (ret != -EIOCBQUEUED)
|
|
ovl_aio_cleanup_handler(aio_req);
|
|
}
|
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out:
|
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revert_creds(old_cred);
|
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out_fdput:
|
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fdput(real);
|
|
|
|
out_unlock:
|
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inode_unlock(inode);
|
|
|
|
return ret;
|
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}
|
|
|
|
/*
|
|
* Calling iter_file_splice_write() directly from overlay's f_op may deadlock
|
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* due to lock order inversion between pipe->mutex in iter_file_splice_write()
|
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* and file_start_write(real.file) in ovl_write_iter().
|
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*
|
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* So do everything ovl_write_iter() does and call iter_file_splice_write() on
|
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* the real file.
|
|
*/
|
|
static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
struct fd real;
|
|
const struct cred *old_cred;
|
|
struct inode *inode = file_inode(out);
|
|
ssize_t ret;
|
|
|
|
inode_lock(inode);
|
|
/* Update mode */
|
|
ovl_copyattr(inode);
|
|
ret = file_remove_privs(out);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
ret = ovl_real_fdget(out, &real);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
old_cred = ovl_override_creds(inode->i_sb);
|
|
file_start_write(real.file);
|
|
|
|
ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);
|
|
|
|
file_end_write(real.file);
|
|
/* Update size */
|
|
ovl_copyattr(inode);
|
|
revert_creds(old_cred);
|
|
fdput(real);
|
|
|
|
out_unlock:
|
|
inode_unlock(inode);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
|
|
{
|
|
struct fd real;
|
|
const struct cred *old_cred;
|
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int ret;
|
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|
|
ret = ovl_sync_status(OVL_FS(file_inode(file)->i_sb));
|
|
if (ret <= 0)
|
|
return ret;
|
|
|
|
ret = ovl_real_fdget_meta(file, &real, !datasync);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/* Don't sync lower file for fear of receiving EROFS error */
|
|
if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
|
|
old_cred = ovl_override_creds(file_inode(file)->i_sb);
|
|
ret = vfs_fsync_range(real.file, start, end, datasync);
|
|
revert_creds(old_cred);
|
|
}
|
|
|
|
fdput(real);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
struct file *realfile = file->private_data;
|
|
const struct cred *old_cred;
|
|
int ret;
|
|
|
|
if (!realfile->f_op->mmap)
|
|
return -ENODEV;
|
|
|
|
if (WARN_ON(file != vma->vm_file))
|
|
return -EIO;
|
|
|
|
vma_set_file(vma, realfile);
|
|
|
|
old_cred = ovl_override_creds(file_inode(file)->i_sb);
|
|
ret = call_mmap(vma->vm_file, vma);
|
|
revert_creds(old_cred);
|
|
ovl_file_accessed(file);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
|
|
{
|
|
struct inode *inode = file_inode(file);
|
|
struct fd real;
|
|
const struct cred *old_cred;
|
|
int ret;
|
|
|
|
inode_lock(inode);
|
|
/* Update mode */
|
|
ovl_copyattr(inode);
|
|
ret = file_remove_privs(file);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
ret = ovl_real_fdget(file, &real);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
old_cred = ovl_override_creds(file_inode(file)->i_sb);
|
|
ret = vfs_fallocate(real.file, mode, offset, len);
|
|
revert_creds(old_cred);
|
|
|
|
/* Update size */
|
|
ovl_copyattr(inode);
|
|
|
|
fdput(real);
|
|
|
|
out_unlock:
|
|
inode_unlock(inode);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
|
|
{
|
|
struct fd real;
|
|
const struct cred *old_cred;
|
|
int ret;
|
|
|
|
ret = ovl_real_fdget(file, &real);
|
|
if (ret)
|
|
return ret;
|
|
|
|
old_cred = ovl_override_creds(file_inode(file)->i_sb);
|
|
ret = vfs_fadvise(real.file, offset, len, advice);
|
|
revert_creds(old_cred);
|
|
|
|
fdput(real);
|
|
|
|
return ret;
|
|
}
|
|
|
|
enum ovl_copyop {
|
|
OVL_COPY,
|
|
OVL_CLONE,
|
|
OVL_DEDUPE,
|
|
};
|
|
|
|
static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
|
|
struct file *file_out, loff_t pos_out,
|
|
loff_t len, unsigned int flags, enum ovl_copyop op)
|
|
{
|
|
struct inode *inode_out = file_inode(file_out);
|
|
struct fd real_in, real_out;
|
|
const struct cred *old_cred;
|
|
loff_t ret;
|
|
|
|
inode_lock(inode_out);
|
|
if (op != OVL_DEDUPE) {
|
|
/* Update mode */
|
|
ovl_copyattr(inode_out);
|
|
ret = file_remove_privs(file_out);
|
|
if (ret)
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = ovl_real_fdget(file_out, &real_out);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
ret = ovl_real_fdget(file_in, &real_in);
|
|
if (ret) {
|
|
fdput(real_out);
|
|
goto out_unlock;
|
|
}
|
|
|
|
old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
|
|
switch (op) {
|
|
case OVL_COPY:
|
|
ret = vfs_copy_file_range(real_in.file, pos_in,
|
|
real_out.file, pos_out, len, flags);
|
|
break;
|
|
|
|
case OVL_CLONE:
|
|
ret = vfs_clone_file_range(real_in.file, pos_in,
|
|
real_out.file, pos_out, len, flags);
|
|
break;
|
|
|
|
case OVL_DEDUPE:
|
|
ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
|
|
real_out.file, pos_out, len,
|
|
flags);
|
|
break;
|
|
}
|
|
revert_creds(old_cred);
|
|
|
|
/* Update size */
|
|
ovl_copyattr(inode_out);
|
|
|
|
fdput(real_in);
|
|
fdput(real_out);
|
|
|
|
out_unlock:
|
|
inode_unlock(inode_out);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
|
|
struct file *file_out, loff_t pos_out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
|
|
OVL_COPY);
|
|
}
|
|
|
|
static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
|
|
struct file *file_out, loff_t pos_out,
|
|
loff_t len, unsigned int remap_flags)
|
|
{
|
|
enum ovl_copyop op;
|
|
|
|
if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
|
|
return -EINVAL;
|
|
|
|
if (remap_flags & REMAP_FILE_DEDUP)
|
|
op = OVL_DEDUPE;
|
|
else
|
|
op = OVL_CLONE;
|
|
|
|
/*
|
|
* Don't copy up because of a dedupe request, this wouldn't make sense
|
|
* most of the time (data would be duplicated instead of deduplicated).
|
|
*/
|
|
if (op == OVL_DEDUPE &&
|
|
(!ovl_inode_upper(file_inode(file_in)) ||
|
|
!ovl_inode_upper(file_inode(file_out))))
|
|
return -EPERM;
|
|
|
|
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len,
|
|
remap_flags, op);
|
|
}
|
|
|
|
static int ovl_flush(struct file *file, fl_owner_t id)
|
|
{
|
|
struct fd real;
|
|
const struct cred *old_cred;
|
|
int err;
|
|
|
|
err = ovl_real_fdget(file, &real);
|
|
if (err)
|
|
return err;
|
|
|
|
if (real.file->f_op->flush) {
|
|
old_cred = ovl_override_creds(file_inode(file)->i_sb);
|
|
err = real.file->f_op->flush(real.file, id);
|
|
revert_creds(old_cred);
|
|
}
|
|
fdput(real);
|
|
|
|
return err;
|
|
}
|
|
|
|
const struct file_operations ovl_file_operations = {
|
|
.open = ovl_open,
|
|
.release = ovl_release,
|
|
.llseek = ovl_llseek,
|
|
.read_iter = ovl_read_iter,
|
|
.write_iter = ovl_write_iter,
|
|
.fsync = ovl_fsync,
|
|
.mmap = ovl_mmap,
|
|
.fallocate = ovl_fallocate,
|
|
.fadvise = ovl_fadvise,
|
|
.flush = ovl_flush,
|
|
.splice_read = generic_file_splice_read,
|
|
.splice_write = ovl_splice_write,
|
|
|
|
.copy_file_range = ovl_copy_file_range,
|
|
.remap_file_range = ovl_remap_file_range,
|
|
};
|
|
|
|
int __init ovl_aio_request_cache_init(void)
|
|
{
|
|
ovl_aio_request_cachep = kmem_cache_create("ovl_aio_req",
|
|
sizeof(struct ovl_aio_req),
|
|
0, SLAB_HWCACHE_ALIGN, NULL);
|
|
if (!ovl_aio_request_cachep)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void ovl_aio_request_cache_destroy(void)
|
|
{
|
|
kmem_cache_destroy(ovl_aio_request_cachep);
|
|
}
|