freebsd-dev/module/zcommon/zfs_uio.c
Chunwei Chen 502923bb44 Fix uio_prefaultpages for 0 length iovec
Userspace can freely pass in whatever iovec it feels like, and it's perfectly
legal to pass an iovec which contains a zero length segment. In the current
implementation, uio_prefaultpages would touch an out of bound byte in the
"last byte" logic. While this probably wouldn't cause any critical error, we
would like uio_prefaultpages to be able to continue gracefully.

Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4078
2015-12-15 16:19:55 -08:00

259 lines
6.0 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
/*
* University Copyright- Copyright (c) 1982, 1986, 1988
* The Regents of the University of California
* All Rights Reserved
*
* University Acknowledgment- Portions of this document are derived from
* software developed by the University of California, Berkeley, and its
* contributors.
*/
/*
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
*/
/*
* The uio support from OpenSolaris has been added as a short term
* work around. The hope is to adopt native Linux type and drop the
* use of uio's entirely. Under Linux they only add overhead and
* when possible we want to use native APIs for the ZPL layer.
*/
#ifdef _KERNEL
#include <sys/types.h>
#include <sys/uio_impl.h>
#include <linux/kmap_compat.h>
/*
* Move "n" bytes at byte address "p"; "rw" indicates the direction
* of the move, and the I/O parameters are provided in "uio", which is
* update to reflect the data which was moved. Returns 0 on success or
* a non-zero errno on failure.
*/
static int
uiomove_iov(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
const struct iovec *iov = uio->uio_iov;
size_t skip = uio->uio_skip;
ulong_t cnt;
while (n && uio->uio_resid) {
cnt = MIN(iov->iov_len - skip, n);
switch (uio->uio_segflg) {
case UIO_USERSPACE:
case UIO_USERISPACE:
/*
* p = kernel data pointer
* iov->iov_base = user data pointer
*/
if (rw == UIO_READ) {
if (copy_to_user(iov->iov_base+skip, p, cnt))
return (EFAULT);
} else {
if (copy_from_user(p, iov->iov_base+skip, cnt))
return (EFAULT);
}
break;
case UIO_SYSSPACE:
if (rw == UIO_READ)
bcopy(p, iov->iov_base + skip, cnt);
else
bcopy(iov->iov_base + skip, p, cnt);
break;
default:
ASSERT(0);
}
skip += cnt;
if (skip == iov->iov_len) {
skip = 0;
uio->uio_iov = (++iov);
uio->uio_iovcnt--;
}
uio->uio_skip = skip;
uio->uio_resid -= cnt;
uio->uio_loffset += cnt;
p = (caddr_t)p + cnt;
n -= cnt;
}
return (0);
}
static int
uiomove_bvec(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
const struct bio_vec *bv = uio->uio_bvec;
size_t skip = uio->uio_skip;
ulong_t cnt;
while (n && uio->uio_resid) {
void *paddr;
cnt = MIN(bv->bv_len - skip, n);
paddr = zfs_kmap_atomic(bv->bv_page, KM_USER1);
if (rw == UIO_READ)
bcopy(p, paddr + bv->bv_offset + skip, cnt);
else
bcopy(paddr + bv->bv_offset + skip, p, cnt);
zfs_kunmap_atomic(paddr, KM_USER1);
skip += cnt;
if (skip == bv->bv_len) {
skip = 0;
uio->uio_bvec = (++bv);
uio->uio_iovcnt--;
}
uio->uio_skip = skip;
uio->uio_resid -= cnt;
uio->uio_loffset += cnt;
p = (caddr_t)p + cnt;
n -= cnt;
}
return (0);
}
int
uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
if (uio->uio_segflg != UIO_BVEC)
return (uiomove_iov(p, n, rw, uio));
else
return (uiomove_bvec(p, n, rw, uio));
}
EXPORT_SYMBOL(uiomove);
#define fuword8(uptr, vptr) get_user((*vptr), (uptr))
/*
* Fault in the pages of the first n bytes specified by the uio structure.
* 1 byte in each page is touched and the uio struct is unmodified. Any
* error will terminate the process as this is only a best attempt to get
* the pages resident.
*/
void
uio_prefaultpages(ssize_t n, struct uio *uio)
{
const struct iovec *iov;
ulong_t cnt, incr;
caddr_t p;
uint8_t tmp;
int iovcnt;
size_t skip;
/* no need to fault in kernel pages */
switch (uio->uio_segflg) {
case UIO_SYSSPACE:
case UIO_BVEC:
return;
case UIO_USERSPACE:
case UIO_USERISPACE:
break;
default:
ASSERT(0);
}
iov = uio->uio_iov;
iovcnt = uio->uio_iovcnt;
skip = uio->uio_skip;
for (; n > 0 && iovcnt > 0; iov++, iovcnt--, skip = 0) {
cnt = MIN(iov->iov_len - skip, n);
/* empty iov */
if (cnt == 0)
continue;
n -= cnt;
/*
* touch each page in this segment.
*/
p = iov->iov_base + skip;
while (cnt) {
if (fuword8((uint8_t *) p, &tmp))
return;
incr = MIN(cnt, PAGESIZE);
p += incr;
cnt -= incr;
}
/*
* touch the last byte in case it straddles a page.
*/
p--;
if (fuword8((uint8_t *) p, &tmp))
return;
}
}
EXPORT_SYMBOL(uio_prefaultpages);
/*
* same as uiomove() but doesn't modify uio structure.
* return in cbytes how many bytes were copied.
*/
int
uiocopy(void *p, size_t n, enum uio_rw rw, struct uio *uio, size_t *cbytes)
{
struct uio uio_copy;
int ret;
bcopy(uio, &uio_copy, sizeof (struct uio));
ret = uiomove(p, n, rw, &uio_copy);
*cbytes = uio->uio_resid - uio_copy.uio_resid;
return (ret);
}
EXPORT_SYMBOL(uiocopy);
/*
* Drop the next n chars out of *uiop.
*/
void
uioskip(uio_t *uiop, size_t n)
{
if (n > uiop->uio_resid)
return;
uiop->uio_skip += n;
if (uiop->uio_segflg != UIO_BVEC) {
while (uiop->uio_iovcnt &&
uiop->uio_skip >= uiop->uio_iov->iov_len) {
uiop->uio_skip -= uiop->uio_iov->iov_len;
uiop->uio_iov++;
uiop->uio_iovcnt--;
}
} else {
while (uiop->uio_iovcnt &&
uiop->uio_skip >= uiop->uio_bvec->bv_len) {
uiop->uio_skip -= uiop->uio_bvec->bv_len;
uiop->uio_bvec++;
uiop->uio_iovcnt--;
}
}
uiop->uio_loffset += n;
uiop->uio_resid -= n;
}
EXPORT_SYMBOL(uioskip);
#endif /* _KERNEL */