freebsd-skq/sys/security/audit/audit_arg.c
csjp 118c82a5e3 Fix the handling of IPv6 addresses for subject and process BSM audit
tokens. Currently, we do not support the set{get}audit_addr(2) system
calls which allows processes like sshd to set extended or ip6
information for subject tokens.

The approach that was taken was to change the process audit state
slightly to use an extended terminal ID in the kernel. This allows
us to store both IPv4 IPv6 addresses. In the case that an IPv4 address
is in use, we convert the terminal ID from an struct auditinfo_addr to
a struct auditinfo.

If getaudit(2) is called when the subject is bound to an ip6 address,
we return E2BIG.

- Change the internal audit record to store an extended terminal ID
- Introduce ARG_TERMID_ADDR
- Change the kaudit <-> BSM conversion process so that we are using
  the appropriate subject token. If the address associated with the
  subject is IPv4, we use the standard subject32 token. If the subject
  has an IPv6 address associated with them, we use an extended subject32
  token.
- Fix a couple of endian issues where we do a couple of byte swaps when
  we shouldn't be. IP addresses are already in the correct byte order,
  so reading the ip6 address 4 bytes at a time and swapping them results
  in in-correct address data. It should be noted that the same issue was
  found in the openbsm library and it has been changed there too on the
  vendor branch
- Change A_GETPINFO to use the appropriate structures
- Implement A_GETPINFO_ADDR which basically does what A_GETPINFO does,
  but can also handle ip6 addresses
- Adjust get{set}audit(2) syscalls to convert the data
  auditinfo <-> auditinfo_addr
- Fully implement set{get}audit_addr(2)

NOTE: This adds the ability for processes to correctly set extended subject
information. The appropriate userspace utilities still need to be updated.

MFC after:	1 month
Reviewed by:	rwatson
Obtained from:	TrustedBSD
2007-04-13 14:55:19 +00:00

834 lines
17 KiB
C

/*
* Copyright (c) 1999-2005 Apple Computer, Inc.
* 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 Apple Computer, Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/filedesc.h>
#include <sys/ipc.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/sbuf.h>
#include <sys/systm.h>
#include <sys/un.h>
#include <sys/vnode.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <security/audit/audit.h>
#include <security/audit/audit_private.h>
/*
* Calls to manipulate elements of the audit record structure from system
* call code. Macro wrappers will prevent this functions from being
* entered if auditing is disabled, avoiding the function call cost. We
* check the thread audit record pointer anyway, as the audit condition
* could change, and pre-selection may not have allocated an audit
* record for this event.
*
* XXXAUDIT: Should we assert, in each case, that this field of the record
* hasn't already been filled in?
*/
void
audit_arg_addr(void * addr)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_addr = addr;
ARG_SET_VALID(ar, ARG_ADDR);
}
void
audit_arg_exit(int status, int retval)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_exitstatus = status;
ar->k_ar.ar_arg_exitretval = retval;
ARG_SET_VALID(ar, ARG_EXIT);
}
void
audit_arg_len(int len)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_len = len;
ARG_SET_VALID(ar, ARG_LEN);
}
void
audit_arg_fd(int fd)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_fd = fd;
ARG_SET_VALID(ar, ARG_FD);
}
void
audit_arg_fflags(int fflags)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_fflags = fflags;
ARG_SET_VALID(ar, ARG_FFLAGS);
}
void
audit_arg_gid(gid_t gid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_gid = gid;
ARG_SET_VALID(ar, ARG_GID);
}
void
audit_arg_uid(uid_t uid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_uid = uid;
ARG_SET_VALID(ar, ARG_UID);
}
void
audit_arg_egid(gid_t egid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_egid = egid;
ARG_SET_VALID(ar, ARG_EGID);
}
void
audit_arg_euid(uid_t euid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_euid = euid;
ARG_SET_VALID(ar, ARG_EUID);
}
void
audit_arg_rgid(gid_t rgid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_rgid = rgid;
ARG_SET_VALID(ar, ARG_RGID);
}
void
audit_arg_ruid(uid_t ruid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_ruid = ruid;
ARG_SET_VALID(ar, ARG_RUID);
}
void
audit_arg_sgid(gid_t sgid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_sgid = sgid;
ARG_SET_VALID(ar, ARG_SGID);
}
void
audit_arg_suid(uid_t suid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_suid = suid;
ARG_SET_VALID(ar, ARG_SUID);
}
void
audit_arg_groupset(gid_t *gidset, u_int gidset_size)
{
int i;
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
for (i = 0; i < gidset_size; i++)
ar->k_ar.ar_arg_groups.gidset[i] = gidset[i];
ar->k_ar.ar_arg_groups.gidset_size = gidset_size;
ARG_SET_VALID(ar, ARG_GROUPSET);
}
void
audit_arg_login(char *login)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
strlcpy(ar->k_ar.ar_arg_login, login, MAXLOGNAME);
ARG_SET_VALID(ar, ARG_LOGIN);
}
void
audit_arg_ctlname(int *name, int namelen)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
bcopy(name, &ar->k_ar.ar_arg_ctlname, namelen * sizeof(int));
ar->k_ar.ar_arg_len = namelen;
ARG_SET_VALID(ar, ARG_CTLNAME | ARG_LEN);
}
void
audit_arg_mask(int mask)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_mask = mask;
ARG_SET_VALID(ar, ARG_MASK);
}
void
audit_arg_mode(mode_t mode)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_mode = mode;
ARG_SET_VALID(ar, ARG_MODE);
}
void
audit_arg_dev(int dev)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_dev = dev;
ARG_SET_VALID(ar, ARG_DEV);
}
void
audit_arg_value(long value)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_value = value;
ARG_SET_VALID(ar, ARG_VALUE);
}
void
audit_arg_owner(uid_t uid, gid_t gid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_uid = uid;
ar->k_ar.ar_arg_gid = gid;
ARG_SET_VALID(ar, ARG_UID | ARG_GID);
}
void
audit_arg_pid(pid_t pid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_pid = pid;
ARG_SET_VALID(ar, ARG_PID);
}
void
audit_arg_process(struct proc *p)
{
struct kaudit_record *ar;
KASSERT(p != NULL, ("audit_arg_process: p == NULL"));
PROC_LOCK_ASSERT(p, MA_OWNED);
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_auid = p->p_au->ai_auid;
ar->k_ar.ar_arg_euid = p->p_ucred->cr_uid;
ar->k_ar.ar_arg_egid = p->p_ucred->cr_groups[0];
ar->k_ar.ar_arg_ruid = p->p_ucred->cr_ruid;
ar->k_ar.ar_arg_rgid = p->p_ucred->cr_rgid;
ar->k_ar.ar_arg_asid = p->p_au->ai_asid;
ar->k_ar.ar_arg_termid_addr = p->p_au->ai_termid;
ar->k_ar.ar_arg_pid = p->p_pid;
ARG_SET_VALID(ar, ARG_AUID | ARG_EUID | ARG_EGID | ARG_RUID |
ARG_RGID | ARG_ASID | ARG_TERMID_ADDR | ARG_PID | ARG_PROCESS);
}
void
audit_arg_signum(u_int signum)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_signum = signum;
ARG_SET_VALID(ar, ARG_SIGNUM);
}
void
audit_arg_socket(int sodomain, int sotype, int soprotocol)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_sockinfo.so_domain = sodomain;
ar->k_ar.ar_arg_sockinfo.so_type = sotype;
ar->k_ar.ar_arg_sockinfo.so_protocol = soprotocol;
ARG_SET_VALID(ar, ARG_SOCKINFO);
}
void
audit_arg_sockaddr(struct thread *td, struct sockaddr *sa)
{
struct kaudit_record *ar;
KASSERT(td != NULL, ("audit_arg_sockaddr: td == NULL"));
KASSERT(sa != NULL, ("audit_arg_sockaddr: sa == NULL"));
ar = currecord();
if (ar == NULL)
return;
bcopy(sa, &ar->k_ar.ar_arg_sockaddr, sa->sa_len);
switch (sa->sa_family) {
case AF_INET:
ARG_SET_VALID(ar, ARG_SADDRINET);
break;
case AF_INET6:
ARG_SET_VALID(ar, ARG_SADDRINET6);
break;
case AF_UNIX:
audit_arg_upath(td, ((struct sockaddr_un *)sa)->sun_path,
ARG_UPATH1);
ARG_SET_VALID(ar, ARG_SADDRUNIX);
break;
/* XXXAUDIT: default:? */
}
}
void
audit_arg_auid(uid_t auid)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_auid = auid;
ARG_SET_VALID(ar, ARG_AUID);
}
void
audit_arg_auditinfo(struct auditinfo *au_info)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_auid = au_info->ai_auid;
ar->k_ar.ar_arg_asid = au_info->ai_asid;
ar->k_ar.ar_arg_amask.am_success = au_info->ai_mask.am_success;
ar->k_ar.ar_arg_amask.am_failure = au_info->ai_mask.am_failure;
ar->k_ar.ar_arg_termid.port = au_info->ai_termid.port;
ar->k_ar.ar_arg_termid.machine = au_info->ai_termid.machine;
ARG_SET_VALID(ar, ARG_AUID | ARG_ASID | ARG_AMASK | ARG_TERMID);
}
void
audit_arg_text(char *text)
{
struct kaudit_record *ar;
KASSERT(text != NULL, ("audit_arg_text: text == NULL"));
ar = currecord();
if (ar == NULL)
return;
/* Invalidate the text string */
ar->k_ar.ar_valid_arg &= (ARG_ALL ^ ARG_TEXT);
if (ar->k_ar.ar_arg_text == NULL)
ar->k_ar.ar_arg_text = malloc(MAXPATHLEN, M_AUDITTEXT,
M_WAITOK);
strncpy(ar->k_ar.ar_arg_text, text, MAXPATHLEN);
ARG_SET_VALID(ar, ARG_TEXT);
}
void
audit_arg_cmd(int cmd)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_cmd = cmd;
ARG_SET_VALID(ar, ARG_CMD);
}
void
audit_arg_svipc_cmd(int cmd)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_svipc_cmd = cmd;
ARG_SET_VALID(ar, ARG_SVIPC_CMD);
}
void
audit_arg_svipc_perm(struct ipc_perm *perm)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
bcopy(perm, &ar->k_ar.ar_arg_svipc_perm,
sizeof(ar->k_ar.ar_arg_svipc_perm));
ARG_SET_VALID(ar, ARG_SVIPC_PERM);
}
void
audit_arg_svipc_id(int id)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_svipc_id = id;
ARG_SET_VALID(ar, ARG_SVIPC_ID);
}
void
audit_arg_svipc_addr(void * addr)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_svipc_addr = addr;
ARG_SET_VALID(ar, ARG_SVIPC_ADDR);
}
void
audit_arg_posix_ipc_perm(uid_t uid, gid_t gid, mode_t mode)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_pipc_perm.pipc_uid = uid;
ar->k_ar.ar_arg_pipc_perm.pipc_gid = gid;
ar->k_ar.ar_arg_pipc_perm.pipc_mode = mode;
ARG_SET_VALID(ar, ARG_POSIX_IPC_PERM);
}
void
audit_arg_auditon(union auditon_udata *udata)
{
struct kaudit_record *ar;
ar = currecord();
if (ar == NULL)
return;
bcopy((void *)udata, &ar->k_ar.ar_arg_auditon,
sizeof(ar->k_ar.ar_arg_auditon));
ARG_SET_VALID(ar, ARG_AUDITON);
}
/*
* Audit information about a file, either the file's vnode info, or its
* socket address info.
*/
void
audit_arg_file(struct proc *p, struct file *fp)
{
struct kaudit_record *ar;
struct socket *so;
struct inpcb *pcb;
struct vnode *vp;
int vfslocked;
ar = currecord();
if (ar == NULL)
return;
switch (fp->f_type) {
case DTYPE_VNODE:
case DTYPE_FIFO:
/*
* XXXAUDIT: Only possibly to record as first vnode?
*/
vp = fp->f_vnode;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
audit_arg_vnode(vp, ARG_VNODE1);
VOP_UNLOCK(vp, 0, curthread);
VFS_UNLOCK_GIANT(vfslocked);
break;
case DTYPE_SOCKET:
so = (struct socket *)fp->f_data;
if (INP_CHECK_SOCKAF(so, PF_INET)) {
SOCK_LOCK(so);
ar->k_ar.ar_arg_sockinfo.so_type =
so->so_type;
ar->k_ar.ar_arg_sockinfo.so_domain =
INP_SOCKAF(so);
ar->k_ar.ar_arg_sockinfo.so_protocol =
so->so_proto->pr_protocol;
SOCK_UNLOCK(so);
pcb = (struct inpcb *)so->so_pcb;
INP_LOCK(pcb);
ar->k_ar.ar_arg_sockinfo.so_raddr =
pcb->inp_faddr.s_addr;
ar->k_ar.ar_arg_sockinfo.so_laddr =
pcb->inp_laddr.s_addr;
ar->k_ar.ar_arg_sockinfo.so_rport =
pcb->inp_fport;
ar->k_ar.ar_arg_sockinfo.so_lport =
pcb->inp_lport;
INP_UNLOCK(pcb);
ARG_SET_VALID(ar, ARG_SOCKINFO);
}
break;
default:
/* XXXAUDIT: else? */
break;
}
}
/*
* Store a path as given by the user process for auditing into the audit
* record stored on the user thread. This function will allocate the memory
* to store the path info if not already available. This memory will be freed
* when the audit record is freed.
*
* XXXAUDIT: Possibly assert that the memory isn't already allocated?
*/
void
audit_arg_upath(struct thread *td, char *upath, u_int64_t flag)
{
struct kaudit_record *ar;
char **pathp;
KASSERT(td != NULL, ("audit_arg_upath: td == NULL"));
KASSERT(upath != NULL, ("audit_arg_upath: upath == NULL"));
ar = currecord();
if (ar == NULL)
return;
KASSERT((flag == ARG_UPATH1) || (flag == ARG_UPATH2),
("audit_arg_upath: flag %llu", (unsigned long long)flag));
KASSERT((flag != ARG_UPATH1) || (flag != ARG_UPATH2),
("audit_arg_upath: flag %llu", (unsigned long long)flag));
if (flag == ARG_UPATH1)
pathp = &ar->k_ar.ar_arg_upath1;
else
pathp = &ar->k_ar.ar_arg_upath2;
if (*pathp == NULL)
*pathp = malloc(MAXPATHLEN, M_AUDITPATH, M_WAITOK);
canon_path(td, upath, *pathp);
ARG_SET_VALID(ar, flag);
}
/*
* Function to save the path and vnode attr information into the audit
* record.
*
* It is assumed that the caller will hold any vnode locks necessary to
* perform a VOP_GETATTR() on the passed vnode.
*
* XXX: The attr code is very similar to vfs_vnops.c:vn_stat(), but
* always provides access to the generation number as we need that
* to construct the BSM file ID.
* XXX: We should accept the process argument from the caller, since
* it's very likely they already have a reference.
* XXX: Error handling in this function is poor.
*
* XXXAUDIT: Possibly KASSERT the path pointer is NULL?
*/
void
audit_arg_vnode(struct vnode *vp, u_int64_t flags)
{
struct kaudit_record *ar;
struct vattr vattr;
int error;
struct vnode_au_info *vnp;
KASSERT(vp != NULL, ("audit_arg_vnode: vp == NULL"));
KASSERT((flags == ARG_VNODE1) || (flags == ARG_VNODE2),
("audit_arg_vnode: flags %jd", (intmax_t)flags));
/*
* Assume that if the caller is calling audit_arg_vnode() on a
* non-MPSAFE vnode, then it will have acquired Giant.
*/
VFS_ASSERT_GIANT(vp->v_mount);
ASSERT_VOP_LOCKED(vp, "audit_arg_vnode");
ar = currecord();
if (ar == NULL)
return;
/*
* XXXAUDIT: The below clears, and then resets the flags for valid
* arguments. Ideally, either the new vnode is used, or the old one
* would be.
*/
if (flags & ARG_VNODE1) {
ar->k_ar.ar_valid_arg &= (ARG_ALL ^ ARG_VNODE1);
vnp = &ar->k_ar.ar_arg_vnode1;
} else {
ar->k_ar.ar_valid_arg &= (ARG_ALL ^ ARG_VNODE2);
vnp = &ar->k_ar.ar_arg_vnode2;
}
error = VOP_GETATTR(vp, &vattr, curthread->td_ucred, curthread);
if (error) {
/* XXX: How to handle this case? */
return;
}
vnp->vn_mode = vattr.va_mode;
vnp->vn_uid = vattr.va_uid;
vnp->vn_gid = vattr.va_gid;
vnp->vn_dev = vattr.va_rdev;
vnp->vn_fsid = vattr.va_fsid;
vnp->vn_fileid = vattr.va_fileid;
vnp->vn_gen = vattr.va_gen;
if (flags & ARG_VNODE1)
ARG_SET_VALID(ar, ARG_VNODE1);
else
ARG_SET_VALID(ar, ARG_VNODE2);
}
/*
* Audit the argument strings passed to exec.
*/
void
audit_arg_argv(char *argv, int argc, int length)
{
struct kaudit_record *ar;
if (audit_argv == 0)
return;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_argv = malloc(length, M_AUDITTEXT, M_WAITOK);
bcopy(argv, ar->k_ar.ar_arg_argv, length);
ar->k_ar.ar_arg_argc = argc;
ARG_SET_VALID(ar, ARG_ARGV);
}
/*
* Audit the environment strings passed to exec.
*/
void
audit_arg_envv(char *envv, int envc, int length)
{
struct kaudit_record *ar;
if (audit_arge == 0)
return;
ar = currecord();
if (ar == NULL)
return;
ar->k_ar.ar_arg_envv = malloc(length, M_AUDITTEXT, M_WAITOK);
bcopy(envv, ar->k_ar.ar_arg_envv, length);
ar->k_ar.ar_arg_envc = envc;
ARG_SET_VALID(ar, ARG_ENVV);
}
/*
* The close() system call uses it's own audit call to capture the path/vnode
* information because those pieces are not easily obtained within the system
* call itself.
*/
void
audit_sysclose(struct thread *td, int fd)
{
struct kaudit_record *ar;
struct vnode *vp;
struct file *fp;
int vfslocked;
KASSERT(td != NULL, ("audit_sysclose: td == NULL"));
ar = currecord();
if (ar == NULL)
return;
audit_arg_fd(fd);
if (getvnode(td->td_proc->p_fd, fd, &fp) != 0)
return;
vp = fp->f_vnode;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
audit_arg_vnode(vp, ARG_VNODE1);
VOP_UNLOCK(vp, 0, td);
VFS_UNLOCK_GIANT(vfslocked);
fdrop(fp, td);
}