freebsd-skq/sys/fs/deadfs/dead_vnops.c
Mateusz Guzik eb88fed446 cache: fix vexec panic when racing against vgone
Use of dead_vnodeops would result in a panic instead of returning the intended
EOPNOTSUPP error.

While here make sure to abort, not just try to return a partial result.
The former allows the regular lookup to restart from scratch, while the latter
makes it stuck with an unusable vnode.

Reported by:	kevans
2020-10-09 19:10:00 +00:00

162 lines
4.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)dead_vnops.c 8.1 (Berkeley) 6/10/93
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/poll.h>
#include <sys/vnode.h>
/*
* Prototypes for dead operations on vnodes.
*/
static vop_lookup_t dead_lookup;
static vop_open_t dead_open;
static vop_getwritemount_t dead_getwritemount;
static vop_rename_t dead_rename;
static vop_unset_text_t dead_unset_text;
struct vop_vector dead_vnodeops = {
.vop_default = &default_vnodeops,
.vop_access = VOP_EBADF,
.vop_advlock = VOP_EBADF,
.vop_bmap = VOP_EBADF,
.vop_create = VOP_PANIC,
.vop_getattr = VOP_EBADF,
.vop_getwritemount = dead_getwritemount,
.vop_inactive = VOP_NULL,
.vop_ioctl = VOP_EBADF,
.vop_link = VOP_PANIC,
.vop_lookup = dead_lookup,
.vop_mkdir = VOP_PANIC,
.vop_mknod = VOP_PANIC,
.vop_open = dead_open,
.vop_pathconf = VOP_EBADF, /* per pathconf(2) */
.vop_poll = dead_poll,
.vop_read = dead_read,
.vop_readdir = VOP_EBADF,
.vop_readlink = VOP_EBADF,
.vop_reclaim = VOP_NULL,
.vop_remove = VOP_PANIC,
.vop_rename = dead_rename,
.vop_rmdir = VOP_PANIC,
.vop_setattr = VOP_EBADF,
.vop_symlink = VOP_PANIC,
.vop_vptocnp = VOP_EBADF,
.vop_unset_text = dead_unset_text,
.vop_write = dead_write,
.vop_fplookup_vexec = VOP_EOPNOTSUPP,
};
VFS_VOP_VECTOR_REGISTER(dead_vnodeops);
static int
dead_getwritemount(struct vop_getwritemount_args *ap)
{
*(ap->a_mpp) = NULL;
return (0);
}
/*
* Trivial lookup routine that always fails.
*/
static int
dead_lookup(struct vop_lookup_args *ap)
{
*ap->a_vpp = NULL;
return (ENOTDIR);
}
/*
* Open always fails as if device did not exist.
*/
static int
dead_open(struct vop_open_args *ap)
{
return (ENXIO);
}
int
dead_read(struct vop_read_args *ap)
{
/*
* Return EOF for tty devices, EIO for others
*/
if ((ap->a_vp->v_vflag & VV_ISTTY) == 0)
return (EIO);
return (0);
}
int
dead_write(struct vop_write_args *ap)
{
return (EIO);
}
int
dead_poll(struct vop_poll_args *ap)
{
if (ap->a_events & ~POLLSTANDARD)
return (POLLNVAL);
/*
* Let the user find out that the descriptor is gone.
*/
return (POLLHUP | ((POLLIN | POLLRDNORM) & ap->a_events));
}
static int
dead_rename(struct vop_rename_args *ap)
{
vop_rename_fail(ap);
return (EXDEV);
}
static int
dead_unset_text(struct vop_unset_text_args *ap)
{
return (0);
}