freebsd-skq/sys/kern/vfs_extattr.c
rwatson 4af919b491 Second-to-last commit implementing Capsicum capabilities in the FreeBSD
kernel for FreeBSD 9.0:

Add a new capability mask argument to fget(9) and friends, allowing system
call code to declare what capabilities are required when an integer file
descriptor is converted into an in-kernel struct file *.  With options
CAPABILITIES compiled into the kernel, this enforces capability
protection; without, this change is effectively a no-op.

Some cases require special handling, such as mmap(2), which must preserve
information about the maximum rights at the time of mapping in the memory
map so that they can later be enforced in mprotect(2) -- this is done by
narrowing the rights in the existing max_protection field used for similar
purposes with file permissions.

In namei(9), we assert that the code is not reached from within capability
mode, as we're not yet ready to enforce namespace capabilities there.
This will follow in a later commit.

Update two capability names: CAP_EVENT and CAP_KEVENT become
CAP_POST_KEVENT and CAP_POLL_KEVENT to more accurately indicate what they
represent.

Approved by:	re (bz)
Submitted by:	jonathan
Sponsored by:	Google Inc
2011-08-11 12:30:23 +00:00

796 lines
18 KiB
C

/*-
* Copyright (c) 1999-2001 Robert N. M. Watson
* All rights reserved.
*
* This software was developed by Robert Watson for the TrustedBSD Project.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/capability.h>
#include <sys/lock.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/fcntl.h>
#include <sys/namei.h>
#include <sys/filedesc.h>
#include <sys/limits.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/extattr.h>
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
/*
* Syscall to push extended attribute configuration information into the VFS.
* Accepts a path, which it converts to a mountpoint, as well as a command
* (int cmd), and attribute name and misc data.
*
* Currently this is used only by UFS1 extended attributes.
*/
int
extattrctl(td, uap)
struct thread *td;
struct extattrctl_args /* {
const char *path;
int cmd;
const char *filename;
int attrnamespace;
const char *attrname;
} */ *uap;
{
struct vnode *filename_vp;
struct nameidata nd;
struct mount *mp, *mp_writable;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, fnvfslocked, error;
AUDIT_ARG_CMD(uap->cmd);
AUDIT_ARG_VALUE(uap->attrnamespace);
/*
* uap->attrname is not always defined. We check again later when we
* invoke the VFS call so as to pass in NULL there if needed.
*/
if (uap->attrname != NULL) {
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN,
NULL);
if (error)
return (error);
}
AUDIT_ARG_TEXT(attrname);
vfslocked = fnvfslocked = 0;
mp = NULL;
filename_vp = NULL;
if (uap->filename != NULL) {
NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | AUDITVNODE2,
UIO_USERSPACE, uap->filename, td);
error = namei(&nd);
if (error)
return (error);
fnvfslocked = NDHASGIANT(&nd);
filename_vp = nd.ni_vp;
NDFREE(&nd, NDF_NO_VP_RELE);
}
/* uap->path is always defined. */
NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | LOCKLEAF | AUDITVNODE1,
UIO_USERSPACE, uap->path, td);
error = namei(&nd);
if (error)
goto out;
vfslocked = NDHASGIANT(&nd);
mp = nd.ni_vp->v_mount;
error = vfs_busy(mp, 0);
if (error) {
NDFREE(&nd, 0);
mp = NULL;
goto out;
}
VOP_UNLOCK(nd.ni_vp, 0);
error = vn_start_write(nd.ni_vp, &mp_writable, V_WAIT | PCATCH);
NDFREE(&nd, NDF_NO_VP_UNLOCK);
if (error)
goto out;
if (filename_vp != NULL) {
/*
* uap->filename is not always defined. If it is,
* grab a vnode lock, which VFS_EXTATTRCTL() will
* later release.
*/
error = vn_lock(filename_vp, LK_EXCLUSIVE);
if (error) {
vn_finished_write(mp_writable);
goto out;
}
}
error = VFS_EXTATTRCTL(mp, uap->cmd, filename_vp, uap->attrnamespace,
uap->attrname != NULL ? attrname : NULL);
vn_finished_write(mp_writable);
out:
if (mp != NULL)
vfs_unbusy(mp);
/*
* VFS_EXTATTRCTL will have unlocked, but not de-ref'd, filename_vp,
* so vrele it if it is defined.
*/
if (filename_vp != NULL)
vrele(filename_vp);
VFS_UNLOCK_GIANT(fnvfslocked);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
/*-
* Set a named extended attribute on a file or directory
*
* Arguments: unlocked vnode "vp", attribute namespace "attrnamespace",
* kernelspace string pointer "attrname", userspace buffer
* pointer "data", buffer length "nbytes", thread "td".
* Returns: 0 on success, an error number otherwise
* Locks: none
* References: vp must be a valid reference for the duration of the call
*/
static int
extattr_set_vp(struct vnode *vp, int attrnamespace, const char *attrname,
void *data, size_t nbytes, struct thread *td)
{
struct mount *mp;
struct uio auio;
struct iovec aiov;
ssize_t cnt;
int error;
VFS_ASSERT_GIANT(vp->v_mount);
error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
if (error)
return (error);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
aiov.iov_base = data;
aiov.iov_len = nbytes;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = 0;
if (nbytes > INT_MAX) {
error = EINVAL;
goto done;
}
auio.uio_resid = nbytes;
auio.uio_rw = UIO_WRITE;
auio.uio_segflg = UIO_USERSPACE;
auio.uio_td = td;
cnt = nbytes;
#ifdef MAC
error = mac_vnode_check_setextattr(td->td_ucred, vp, attrnamespace,
attrname);
if (error)
goto done;
#endif
error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio,
td->td_ucred, td);
cnt -= auio.uio_resid;
td->td_retval[0] = cnt;
done:
VOP_UNLOCK(vp, 0);
vn_finished_write(mp);
return (error);
}
int
extattr_set_fd(td, uap)
struct thread *td;
struct extattr_set_fd_args /* {
int fd;
int attrnamespace;
const char *attrname;
void *data;
size_t nbytes;
} */ *uap;
{
struct file *fp;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_FD(uap->fd);
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
error = getvnode(td->td_proc->p_fd, uap->fd, CAP_EXTATTR_SET, &fp);
if (error)
return (error);
vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
error = extattr_set_vp(fp->f_vnode, uap->attrnamespace,
attrname, uap->data, uap->nbytes, td);
fdrop(fp, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_set_file(td, uap)
struct thread *td;
struct extattr_set_file_args /* {
const char *path;
int attrnamespace;
const char *attrname;
void *data;
size_t nbytes;
} */ *uap;
{
struct nameidata nd;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_set_vp(nd.ni_vp, uap->attrnamespace, attrname,
uap->data, uap->nbytes, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_set_link(td, uap)
struct thread *td;
struct extattr_set_link_args /* {
const char *path;
int attrnamespace;
const char *attrname;
void *data;
size_t nbytes;
} */ *uap;
{
struct nameidata nd;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
NDINIT(&nd, LOOKUP, MPSAFE | NOFOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_set_vp(nd.ni_vp, uap->attrnamespace, attrname,
uap->data, uap->nbytes, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
/*-
* Get a named extended attribute on a file or directory
*
* Arguments: unlocked vnode "vp", attribute namespace "attrnamespace",
* kernelspace string pointer "attrname", userspace buffer
* pointer "data", buffer length "nbytes", thread "td".
* Returns: 0 on success, an error number otherwise
* Locks: none
* References: vp must be a valid reference for the duration of the call
*/
static int
extattr_get_vp(struct vnode *vp, int attrnamespace, const char *attrname,
void *data, size_t nbytes, struct thread *td)
{
struct uio auio, *auiop;
struct iovec aiov;
ssize_t cnt;
size_t size, *sizep;
int error;
VFS_ASSERT_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
/*
* Slightly unusual semantics: if the user provides a NULL data
* pointer, they don't want to receive the data, just the maximum
* read length.
*/
auiop = NULL;
sizep = NULL;
cnt = 0;
if (data != NULL) {
aiov.iov_base = data;
aiov.iov_len = nbytes;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = 0;
if (nbytes > INT_MAX) {
error = EINVAL;
goto done;
}
auio.uio_resid = nbytes;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_USERSPACE;
auio.uio_td = td;
auiop = &auio;
cnt = nbytes;
} else
sizep = &size;
#ifdef MAC
error = mac_vnode_check_getextattr(td->td_ucred, vp, attrnamespace,
attrname);
if (error)
goto done;
#endif
error = VOP_GETEXTATTR(vp, attrnamespace, attrname, auiop, sizep,
td->td_ucred, td);
if (auiop != NULL) {
cnt -= auio.uio_resid;
td->td_retval[0] = cnt;
} else
td->td_retval[0] = size;
done:
VOP_UNLOCK(vp, 0);
return (error);
}
int
extattr_get_fd(td, uap)
struct thread *td;
struct extattr_get_fd_args /* {
int fd;
int attrnamespace;
const char *attrname;
void *data;
size_t nbytes;
} */ *uap;
{
struct file *fp;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_FD(uap->fd);
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
error = getvnode(td->td_proc->p_fd, uap->fd, CAP_EXTATTR_GET, &fp);
if (error)
return (error);
vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
error = extattr_get_vp(fp->f_vnode, uap->attrnamespace,
attrname, uap->data, uap->nbytes, td);
fdrop(fp, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_get_file(td, uap)
struct thread *td;
struct extattr_get_file_args /* {
const char *path;
int attrnamespace;
const char *attrname;
void *data;
size_t nbytes;
} */ *uap;
{
struct nameidata nd;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_get_vp(nd.ni_vp, uap->attrnamespace, attrname,
uap->data, uap->nbytes, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_get_link(td, uap)
struct thread *td;
struct extattr_get_link_args /* {
const char *path;
int attrnamespace;
const char *attrname;
void *data;
size_t nbytes;
} */ *uap;
{
struct nameidata nd;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
NDINIT(&nd, LOOKUP, MPSAFE | NOFOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_get_vp(nd.ni_vp, uap->attrnamespace, attrname,
uap->data, uap->nbytes, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
/*
* extattr_delete_vp(): Delete a named extended attribute on a file or
* directory
*
* Arguments: unlocked vnode "vp", attribute namespace "attrnamespace",
* kernelspace string pointer "attrname", proc "p"
* Returns: 0 on success, an error number otherwise
* Locks: none
* References: vp must be a valid reference for the duration of the call
*/
static int
extattr_delete_vp(struct vnode *vp, int attrnamespace, const char *attrname,
struct thread *td)
{
struct mount *mp;
int error;
VFS_ASSERT_GIANT(vp->v_mount);
error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
if (error)
return (error);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
#ifdef MAC
error = mac_vnode_check_deleteextattr(td->td_ucred, vp, attrnamespace,
attrname);
if (error)
goto done;
#endif
error = VOP_DELETEEXTATTR(vp, attrnamespace, attrname, td->td_ucred,
td);
if (error == EOPNOTSUPP)
error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
td->td_ucred, td);
#ifdef MAC
done:
#endif
VOP_UNLOCK(vp, 0);
vn_finished_write(mp);
return (error);
}
int
extattr_delete_fd(td, uap)
struct thread *td;
struct extattr_delete_fd_args /* {
int fd;
int attrnamespace;
const char *attrname;
} */ *uap;
{
struct file *fp;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_FD(uap->fd);
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return (error);
AUDIT_ARG_TEXT(attrname);
error = getvnode(td->td_proc->p_fd, uap->fd, CAP_EXTATTR_DELETE,
&fp);
if (error)
return (error);
vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
error = extattr_delete_vp(fp->f_vnode, uap->attrnamespace,
attrname, td);
fdrop(fp, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_delete_file(td, uap)
struct thread *td;
struct extattr_delete_file_args /* {
const char *path;
int attrnamespace;
const char *attrname;
} */ *uap;
{
struct nameidata nd;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return(error);
AUDIT_ARG_TEXT(attrname);
NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return(error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_delete_vp(nd.ni_vp, uap->attrnamespace, attrname, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return(error);
}
int
extattr_delete_link(td, uap)
struct thread *td;
struct extattr_delete_link_args /* {
const char *path;
int attrnamespace;
const char *attrname;
} */ *uap;
{
struct nameidata nd;
char attrname[EXTATTR_MAXNAMELEN];
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
error = copyinstr(uap->attrname, attrname, EXTATTR_MAXNAMELEN, NULL);
if (error)
return(error);
AUDIT_ARG_TEXT(attrname);
NDINIT(&nd, LOOKUP, MPSAFE | NOFOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return(error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_delete_vp(nd.ni_vp, uap->attrnamespace, attrname, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return(error);
}
/*-
* Retrieve a list of extended attributes on a file or directory.
*
* Arguments: unlocked vnode "vp", attribute namespace 'attrnamespace",
* userspace buffer pointer "data", buffer length "nbytes",
* thread "td".
* Returns: 0 on success, an error number otherwise
* Locks: none
* References: vp must be a valid reference for the duration of the call
*/
static int
extattr_list_vp(struct vnode *vp, int attrnamespace, void *data,
size_t nbytes, struct thread *td)
{
struct uio auio, *auiop;
size_t size, *sizep;
struct iovec aiov;
ssize_t cnt;
int error;
VFS_ASSERT_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
auiop = NULL;
sizep = NULL;
cnt = 0;
if (data != NULL) {
aiov.iov_base = data;
aiov.iov_len = nbytes;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = 0;
if (nbytes > INT_MAX) {
error = EINVAL;
goto done;
}
auio.uio_resid = nbytes;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_USERSPACE;
auio.uio_td = td;
auiop = &auio;
cnt = nbytes;
} else
sizep = &size;
#ifdef MAC
error = mac_vnode_check_listextattr(td->td_ucred, vp, attrnamespace);
if (error)
goto done;
#endif
error = VOP_LISTEXTATTR(vp, attrnamespace, auiop, sizep,
td->td_ucred, td);
if (auiop != NULL) {
cnt -= auio.uio_resid;
td->td_retval[0] = cnt;
} else
td->td_retval[0] = size;
done:
VOP_UNLOCK(vp, 0);
return (error);
}
int
extattr_list_fd(td, uap)
struct thread *td;
struct extattr_list_fd_args /* {
int fd;
int attrnamespace;
void *data;
size_t nbytes;
} */ *uap;
{
struct file *fp;
int vfslocked, error;
AUDIT_ARG_FD(uap->fd);
AUDIT_ARG_VALUE(uap->attrnamespace);
error = getvnode(td->td_proc->p_fd, uap->fd, CAP_EXTATTR_LIST, &fp);
if (error)
return (error);
vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
error = extattr_list_vp(fp->f_vnode, uap->attrnamespace, uap->data,
uap->nbytes, td);
fdrop(fp, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_list_file(td, uap)
struct thread*td;
struct extattr_list_file_args /* {
const char *path;
int attrnamespace;
void *data;
size_t nbytes;
} */ *uap;
{
struct nameidata nd;
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_list_vp(nd.ni_vp, uap->attrnamespace, uap->data,
uap->nbytes, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
int
extattr_list_link(td, uap)
struct thread*td;
struct extattr_list_link_args /* {
const char *path;
int attrnamespace;
void *data;
size_t nbytes;
} */ *uap;
{
struct nameidata nd;
int vfslocked, error;
AUDIT_ARG_VALUE(uap->attrnamespace);
NDINIT(&nd, LOOKUP, MPSAFE | NOFOLLOW | AUDITVNODE1, UIO_USERSPACE,
uap->path, td);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vfslocked = NDHASGIANT(&nd);
error = extattr_list_vp(nd.ni_vp, uap->attrnamespace, uap->data,
uap->nbytes, td);
vrele(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}