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freebsd-dev/sys/kern/uipc_usrreq.c
Robert Watson a0ec558af0 Correct a number of serious and closely related bugs in the UNIX domain 
socket file descriptor garbage collection code, which is intended to
detect and clear cycles of orphaned file descriptors that are "in-flight"
in a socket when that socket is closed before they are received.  The
algorithm present was both run at poor times (resulting in recursion and
reentrance), and also buggy in the presence of parallelism.  In order to
fix these problems, make the following changes:

- When there are in-flight sockets and a UNIX domain socket is destroyed,
  asynchronously schedule the garbage collector, rather than running it
  synchronously in the current context.  This avoids lock order issues
  when the garbage collection code reenters the UNIX domain socket code,
  avoiding lock order reversals, deadlocks, etc.  Run the code
  asynchronously in a task queue.

- In the garbage collector, when skipping file descriptors that have
  entered a closing state (i.e., have f_count == 0), re-test the FDEFER
  flag, and decrement unp_defer.  As file descriptors can now transition
  to a closed state, while the garbage collector is running, it is no
  longer the case that unp_defer will remain an accurate count of
  deferred sockets in the mark portion of the GC algorithm.  Otherwise,
  the garbage collector will loop waiting waiting for unp_defer to reach
  zero, which it will never do as it is skipping file descriptors that
  were marked in an earlier pass, but now closed.

- Acquire the UNIX domain socket subsystem lock in unp_discard() when
  modifying the unp_rights counter, or a read/write race is risked with
  other threads also manipulating the counter.

While here:

- Remove #if 0'd code regarding acquiring the socket buffer sleep lock in
  the garbage collector, this is not required as we are able to use the
  socket buffer receive lock to protect scanning the receive buffer for
  in-flight file descriptors on the socket buffer.

- Annotate that the description of the garbage collector implementation
  is increasingly inaccurate and needs to be updated.

- Add counters of the number of deferred garbage collections and recycled
  file descriptors.  This will be removed and is here temporarily for
  debugging purposes.

With these changes in place, the unp_passfd regression test now appears
to be passed consistently on UP and SMP systems for extended runs,
whereas before it hung quickly or panicked, depending on which bug was
triggered.

Reported by:	Philip Kizer <pckizer at nostrum dot com>
MFC after:	2 weeks
2005-11-10 16:06:04 +00:00

1888 lines
44 KiB
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/*-
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California.
* Copyright 2004-2005 Robert N. M. Watson
* 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.
* 4. 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.
*
* From: @(#)uipc_usrreq.c 8.3 (Berkeley) 1/4/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/domain.h>
#include <sys/fcntl.h>
#include <sys/malloc.h> /* XXX must be before <sys/file.h> */
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/resourcevar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/signalvar.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/taskqueue.h>
#include <sys/un.h>
#include <sys/unpcb.h>
#include <sys/vnode.h>
#include <vm/uma.h>
static uma_zone_t unp_zone;
static unp_gen_t unp_gencnt;
static u_int unp_count;
static struct unp_head unp_shead, unp_dhead;
/*
* Unix communications domain.
*
* TODO:
* SEQPACKET, RDM
* rethink name space problems
* need a proper out-of-band
* lock pushdown
*/
static const struct sockaddr sun_noname = { sizeof(sun_noname), AF_LOCAL };
static ino_t unp_ino; /* prototype for fake inode numbers */
struct mbuf *unp_addsockcred(struct thread *, struct mbuf *);
/*
* Currently, UNIX domain sockets are protected by a single subsystem lock,
* which covers global data structures and variables, the contents of each
* per-socket unpcb structure, and the so_pcb field in sockets attached to
* the UNIX domain. This provides for a moderate degree of paralellism, as
* receive operations on UNIX domain sockets do not need to acquire the
* subsystem lock. Finer grained locking to permit send() without acquiring
* a global lock would be a logical next step.
*
* The UNIX domain socket lock preceds all socket layer locks, including the
* socket lock and socket buffer lock, permitting UNIX domain socket code to
* call into socket support routines without releasing its locks.
*
* Some caution is required in areas where the UNIX domain socket code enters
* VFS in order to create or find rendezvous points. This results in
* dropping of the UNIX domain socket subsystem lock, acquisition of the
* Giant lock, and potential sleeping. This increases the chances of races,
* and exposes weaknesses in the socket->protocol API by offering poor
* failure modes.
*/
static struct mtx unp_mtx;
#define UNP_LOCK_INIT() \
mtx_init(&unp_mtx, "unp", NULL, MTX_DEF)
#define UNP_LOCK() mtx_lock(&unp_mtx)
#define UNP_UNLOCK() mtx_unlock(&unp_mtx)
#define UNP_LOCK_ASSERT() mtx_assert(&unp_mtx, MA_OWNED)
#define UNP_UNLOCK_ASSERT() mtx_assert(&unp_mtx, MA_NOTOWNED)
/*
* Garbage collection of cyclic file descriptor/socket references occurs
* asynchronously in a taskqueue context in order to avoid recursion and
* reentrance in the UNIX domain socket, file descriptor, and socket layer
* code. See unp_gc() for a full description.
*/
static struct task unp_gc_task;
static int unp_attach(struct socket *);
static void unp_detach(struct unpcb *);
static int unp_bind(struct unpcb *,struct sockaddr *, struct thread *);
static int unp_connect(struct socket *,struct sockaddr *, struct thread *);
static int unp_connect2(struct socket *so, struct socket *so2, int);
static void unp_disconnect(struct unpcb *);
static void unp_shutdown(struct unpcb *);
static void unp_drop(struct unpcb *, int);
static void unp_gc(__unused void *, int);
static void unp_scan(struct mbuf *, void (*)(struct file *));
static void unp_mark(struct file *);
static void unp_discard(struct file *);
static void unp_freerights(struct file **, int);
static int unp_internalize(struct mbuf **, struct thread *);
static int unp_listen(struct socket *, struct unpcb *, int,
struct thread *);
static int
uipc_abort(struct socket *so)
{
struct unpcb *unp;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
unp_drop(unp, ECONNABORTED);
unp_detach(unp);
UNP_UNLOCK_ASSERT();
ACCEPT_LOCK();
SOCK_LOCK(so);
sotryfree(so);
return (0);
}
static int
uipc_accept(struct socket *so, struct sockaddr **nam)
{
struct unpcb *unp;
const struct sockaddr *sa;
/*
* Pass back name of connected socket,
* if it was bound and we are still connected
* (our peer may have closed already!).
*/
*nam = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
free(*nam, M_SONAME);
*nam = NULL;
return (EINVAL);
}
if (unp->unp_conn != NULL && unp->unp_conn->unp_addr != NULL)
sa = (struct sockaddr *) unp->unp_conn->unp_addr;
else
sa = &sun_noname;
bcopy(sa, *nam, sa->sa_len);
UNP_UNLOCK();
return (0);
}
static int
uipc_attach(struct socket *so, int proto, struct thread *td)
{
struct unpcb *unp = sotounpcb(so);
if (unp != NULL)
return (EISCONN);
return (unp_attach(so));
}
static int
uipc_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
struct unpcb *unp;
int error;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
error = unp_bind(unp, nam, td);
UNP_UNLOCK();
return (error);
}
static int
uipc_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
{
struct unpcb *unp;
int error;
KASSERT(td == curthread, ("uipc_connect: td != curthread"));
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
error = unp_connect(so, nam, td);
UNP_UNLOCK();
return (error);
}
int
uipc_connect2(struct socket *so1, struct socket *so2)
{
struct unpcb *unp;
int error;
UNP_LOCK();
unp = sotounpcb(so1);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
error = unp_connect2(so1, so2, PRU_CONNECT2);
UNP_UNLOCK();
return (error);
}
/* control is EOPNOTSUPP */
static int
uipc_detach(struct socket *so)
{
struct unpcb *unp;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
unp_detach(unp);
UNP_UNLOCK_ASSERT();
return (0);
}
static int
uipc_disconnect(struct socket *so)
{
struct unpcb *unp;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
unp_disconnect(unp);
UNP_UNLOCK();
return (0);
}
static int
uipc_listen(struct socket *so, int backlog, struct thread *td)
{
struct unpcb *unp;
int error;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL || unp->unp_vnode == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
error = unp_listen(so, unp, backlog, td);
UNP_UNLOCK();
return (error);
}
static int
uipc_peeraddr(struct socket *so, struct sockaddr **nam)
{
struct unpcb *unp;
const struct sockaddr *sa;
*nam = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
free(*nam, M_SONAME);
*nam = NULL;
return (EINVAL);
}
if (unp->unp_conn != NULL && unp->unp_conn->unp_addr!= NULL)
sa = (struct sockaddr *) unp->unp_conn->unp_addr;
else {
/*
* XXX: It seems that this test always fails even when
* connection is established. So, this else clause is
* added as workaround to return PF_LOCAL sockaddr.
*/
sa = &sun_noname;
}
bcopy(sa, *nam, sa->sa_len);
UNP_UNLOCK();
return (0);
}
static int
uipc_rcvd(struct socket *so, int flags)
{
struct unpcb *unp;
struct socket *so2;
u_long newhiwat;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
switch (so->so_type) {
case SOCK_DGRAM:
panic("uipc_rcvd DGRAM?");
/*NOTREACHED*/
case SOCK_STREAM:
if (unp->unp_conn == NULL)
break;
so2 = unp->unp_conn->unp_socket;
SOCKBUF_LOCK(&so2->so_snd);
SOCKBUF_LOCK(&so->so_rcv);
/*
* Adjust backpressure on sender
* and wakeup any waiting to write.
*/
so2->so_snd.sb_mbmax += unp->unp_mbcnt - so->so_rcv.sb_mbcnt;
unp->unp_mbcnt = so->so_rcv.sb_mbcnt;
newhiwat = so2->so_snd.sb_hiwat + unp->unp_cc -
so->so_rcv.sb_cc;
(void)chgsbsize(so2->so_cred->cr_uidinfo, &so2->so_snd.sb_hiwat,
newhiwat, RLIM_INFINITY);
unp->unp_cc = so->so_rcv.sb_cc;
SOCKBUF_UNLOCK(&so->so_rcv);
sowwakeup_locked(so2);
break;
default:
panic("uipc_rcvd unknown socktype");
}
UNP_UNLOCK();
return (0);
}
/* pru_rcvoob is EOPNOTSUPP */
static int
uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
struct mbuf *control, struct thread *td)
{
int error = 0;
struct unpcb *unp;
struct socket *so2;
u_long newhiwat;
unp = sotounpcb(so);
if (unp == NULL) {
error = EINVAL;
goto release;
}
if (flags & PRUS_OOB) {
error = EOPNOTSUPP;
goto release;
}
if (control != NULL && (error = unp_internalize(&control, td)))
goto release;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
error = EINVAL;
goto dispose_release;
}
switch (so->so_type) {
case SOCK_DGRAM:
{
const struct sockaddr *from;
if (nam != NULL) {
if (unp->unp_conn != NULL) {
error = EISCONN;
break;
}
error = unp_connect(so, nam, td);
if (error)
break;
} else {
if (unp->unp_conn == NULL) {
error = ENOTCONN;
break;
}
}
so2 = unp->unp_conn->unp_socket;
if (unp->unp_addr != NULL)
from = (struct sockaddr *)unp->unp_addr;
else
from = &sun_noname;
if (unp->unp_conn->unp_flags & UNP_WANTCRED)
control = unp_addsockcred(td, control);
SOCKBUF_LOCK(&so2->so_rcv);
if (sbappendaddr_locked(&so2->so_rcv, from, m, control)) {
sorwakeup_locked(so2);
m = NULL;
control = NULL;
} else {
SOCKBUF_UNLOCK(&so2->so_rcv);
error = ENOBUFS;
}
if (nam != NULL)
unp_disconnect(unp);
break;
}
case SOCK_STREAM:
/* Connect if not connected yet. */
/*
* Note: A better implementation would complain
* if not equal to the peer's address.
*/
if ((so->so_state & SS_ISCONNECTED) == 0) {
if (nam != NULL) {
error = unp_connect(so, nam, td);
if (error)
break; /* XXX */
} else {
error = ENOTCONN;
break;
}
}
SOCKBUF_LOCK(&so->so_snd);
if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
SOCKBUF_UNLOCK(&so->so_snd);
error = EPIPE;
break;
}
if (unp->unp_conn == NULL)
panic("uipc_send connected but no connection?");
so2 = unp->unp_conn->unp_socket;
SOCKBUF_LOCK(&so2->so_rcv);
if (unp->unp_conn->unp_flags & UNP_WANTCRED) {
/*
* Credentials are passed only once on
* SOCK_STREAM.
*/
unp->unp_conn->unp_flags &= ~UNP_WANTCRED;
control = unp_addsockcred(td, control);
}
/*
* Send to paired receive port, and then reduce
* send buffer hiwater marks to maintain backpressure.
* Wake up readers.
*/
if (control != NULL) {
if (sbappendcontrol_locked(&so2->so_rcv, m, control))
control = NULL;
} else {
sbappend_locked(&so2->so_rcv, m);
}
so->so_snd.sb_mbmax -=
so2->so_rcv.sb_mbcnt - unp->unp_conn->unp_mbcnt;
unp->unp_conn->unp_mbcnt = so2->so_rcv.sb_mbcnt;
newhiwat = so->so_snd.sb_hiwat -
(so2->so_rcv.sb_cc - unp->unp_conn->unp_cc);
(void)chgsbsize(so->so_cred->cr_uidinfo, &so->so_snd.sb_hiwat,
newhiwat, RLIM_INFINITY);
SOCKBUF_UNLOCK(&so->so_snd);
unp->unp_conn->unp_cc = so2->so_rcv.sb_cc;
sorwakeup_locked(so2);
m = NULL;
break;
default:
panic("uipc_send unknown socktype");
}
/*
* SEND_EOF is equivalent to a SEND followed by
* a SHUTDOWN.
*/
if (flags & PRUS_EOF) {
socantsendmore(so);
unp_shutdown(unp);
}
UNP_UNLOCK();
dispose_release:
if (control != NULL && error != 0)
unp_dispose(control);
release:
if (control != NULL)
m_freem(control);
if (m != NULL)
m_freem(m);
return (error);
}
static int
uipc_sense(struct socket *so, struct stat *sb)
{
struct unpcb *unp;
struct socket *so2;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
sb->st_blksize = so->so_snd.sb_hiwat;
if (so->so_type == SOCK_STREAM && unp->unp_conn != NULL) {
so2 = unp->unp_conn->unp_socket;
sb->st_blksize += so2->so_rcv.sb_cc;
}
sb->st_dev = NODEV;
if (unp->unp_ino == 0)
unp->unp_ino = (++unp_ino == 0) ? ++unp_ino : unp_ino;
sb->st_ino = unp->unp_ino;
UNP_UNLOCK();
return (0);
}
static int
uipc_shutdown(struct socket *so)
{
struct unpcb *unp;
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
socantsendmore(so);
unp_shutdown(unp);
UNP_UNLOCK();
return (0);
}
static int
uipc_sockaddr(struct socket *so, struct sockaddr **nam)
{
struct unpcb *unp;
const struct sockaddr *sa;
*nam = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
free(*nam, M_SONAME);
*nam = NULL;
return (EINVAL);
}
if (unp->unp_addr != NULL)
sa = (struct sockaddr *) unp->unp_addr;
else
sa = &sun_noname;
bcopy(sa, *nam, sa->sa_len);
UNP_UNLOCK();
return (0);
}
struct pr_usrreqs uipc_usrreqs = {
.pru_abort = uipc_abort,
.pru_accept = uipc_accept,
.pru_attach = uipc_attach,
.pru_bind = uipc_bind,
.pru_connect = uipc_connect,
.pru_connect2 = uipc_connect2,
.pru_detach = uipc_detach,
.pru_disconnect = uipc_disconnect,
.pru_listen = uipc_listen,
.pru_peeraddr = uipc_peeraddr,
.pru_rcvd = uipc_rcvd,
.pru_send = uipc_send,
.pru_sense = uipc_sense,
.pru_shutdown = uipc_shutdown,
.pru_sockaddr = uipc_sockaddr,
.pru_sosend = sosend,
.pru_soreceive = soreceive,
.pru_sopoll = sopoll,
};
int
uipc_ctloutput(struct socket *so, struct sockopt *sopt)
{
struct unpcb *unp;
struct xucred xu;
int error, optval;
if (sopt->sopt_level != 0)
return (EINVAL);
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
UNP_UNLOCK();
return (EINVAL);
}
error = 0;
switch (sopt->sopt_dir) {
case SOPT_GET:
switch (sopt->sopt_name) {
case LOCAL_PEERCRED:
if (unp->unp_flags & UNP_HAVEPC)
xu = unp->unp_peercred;
else {
if (so->so_type == SOCK_STREAM)
error = ENOTCONN;
else
error = EINVAL;
}
if (error == 0)
error = sooptcopyout(sopt, &xu, sizeof(xu));
break;
case LOCAL_CREDS:
optval = unp->unp_flags & UNP_WANTCRED ? 1 : 0;
error = sooptcopyout(sopt, &optval, sizeof(optval));
break;
case LOCAL_CONNWAIT:
optval = unp->unp_flags & UNP_CONNWAIT ? 1 : 0;
error = sooptcopyout(sopt, &optval, sizeof(optval));
break;
default:
error = EOPNOTSUPP;
break;
}
break;
case SOPT_SET:
switch (sopt->sopt_name) {
case LOCAL_CREDS:
case LOCAL_CONNWAIT:
error = sooptcopyin(sopt, &optval, sizeof(optval),
sizeof(optval));
if (error)
break;
#define OPTSET(bit) \
if (optval) \
unp->unp_flags |= bit; \
else \
unp->unp_flags &= ~bit;
switch (sopt->sopt_name) {
case LOCAL_CREDS:
OPTSET(UNP_WANTCRED);
break;
case LOCAL_CONNWAIT:
OPTSET(UNP_CONNWAIT);
break;
default:
break;
}
break;
#undef OPTSET
default:
error = ENOPROTOOPT;
break;
}
break;
default:
error = EOPNOTSUPP;
break;
}
UNP_UNLOCK();
return (error);
}
/*
* Both send and receive buffers are allocated PIPSIZ bytes of buffering
* for stream sockets, although the total for sender and receiver is
* actually only PIPSIZ.
* Datagram sockets really use the sendspace as the maximum datagram size,
* and don't really want to reserve the sendspace. Their recvspace should
* be large enough for at least one max-size datagram plus address.
*/
#ifndef PIPSIZ
#define PIPSIZ 8192
#endif
static u_long unpst_sendspace = PIPSIZ;
static u_long unpst_recvspace = PIPSIZ;
static u_long unpdg_sendspace = 2*1024; /* really max datagram size */
static u_long unpdg_recvspace = 4*1024;
static int unp_rights; /* file descriptors in flight */
SYSCTL_DECL(_net_local_stream);
SYSCTL_INT(_net_local_stream, OID_AUTO, sendspace, CTLFLAG_RW,
&unpst_sendspace, 0, "");
SYSCTL_INT(_net_local_stream, OID_AUTO, recvspace, CTLFLAG_RW,
&unpst_recvspace, 0, "");
SYSCTL_DECL(_net_local_dgram);
SYSCTL_INT(_net_local_dgram, OID_AUTO, maxdgram, CTLFLAG_RW,
&unpdg_sendspace, 0, "");
SYSCTL_INT(_net_local_dgram, OID_AUTO, recvspace, CTLFLAG_RW,
&unpdg_recvspace, 0, "");
SYSCTL_DECL(_net_local);
SYSCTL_INT(_net_local, OID_AUTO, inflight, CTLFLAG_RD, &unp_rights, 0, "");
static int
unp_attach(struct socket *so)
{
struct unpcb *unp;
int error;
if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
switch (so->so_type) {
case SOCK_STREAM:
error = soreserve(so, unpst_sendspace, unpst_recvspace);
break;
case SOCK_DGRAM:
error = soreserve(so, unpdg_sendspace, unpdg_recvspace);
break;
default:
panic("unp_attach");
}
if (error)
return (error);
}
unp = uma_zalloc(unp_zone, M_WAITOK | M_ZERO);
if (unp == NULL)
return (ENOBUFS);
LIST_INIT(&unp->unp_refs);
unp->unp_socket = so;
so->so_pcb = unp;
UNP_LOCK();
unp->unp_gencnt = ++unp_gencnt;
unp_count++;
LIST_INSERT_HEAD(so->so_type == SOCK_DGRAM ? &unp_dhead
: &unp_shead, unp, unp_link);
UNP_UNLOCK();
return (0);
}
static void
unp_detach(struct unpcb *unp)
{
struct vnode *vp;
int local_unp_rights;
UNP_LOCK_ASSERT();
LIST_REMOVE(unp, unp_link);
unp->unp_gencnt = ++unp_gencnt;
--unp_count;
if ((vp = unp->unp_vnode) != NULL) {
/*
* XXXRW: should v_socket be frobbed only while holding
* Giant?
*/
unp->unp_vnode->v_socket = NULL;
unp->unp_vnode = NULL;
}
if (unp->unp_conn != NULL)
unp_disconnect(unp);
while (!LIST_EMPTY(&unp->unp_refs)) {
struct unpcb *ref = LIST_FIRST(&unp->unp_refs);
unp_drop(ref, ECONNRESET);
}
soisdisconnected(unp->unp_socket);
unp->unp_socket->so_pcb = NULL;
local_unp_rights = unp_rights;
UNP_UNLOCK();
if (unp->unp_addr != NULL)
FREE(unp->unp_addr, M_SONAME);
uma_zfree(unp_zone, unp);
if (vp) {
mtx_lock(&Giant);
vrele(vp);
mtx_unlock(&Giant);
}
if (local_unp_rights)
taskqueue_enqueue(taskqueue_thread, &unp_gc_task);
}
static int
unp_bind(struct unpcb *unp, struct sockaddr *nam, struct thread *td)
{
struct sockaddr_un *soun = (struct sockaddr_un *)nam;
struct vnode *vp;
struct mount *mp;
struct vattr vattr;
int error, namelen;
struct nameidata nd;
char *buf;
UNP_LOCK_ASSERT();
/*
* XXXRW: This test-and-set of unp_vnode is non-atomic; the
* unlocked read here is fine, but the value of unp_vnode needs
* to be tested again after we do all the lookups to see if the
* pcb is still unbound?
*/
if (unp->unp_vnode != NULL)
return (EINVAL);
namelen = soun->sun_len - offsetof(struct sockaddr_un, sun_path);
if (namelen <= 0)
return (EINVAL);
UNP_UNLOCK();
buf = malloc(namelen + 1, M_TEMP, M_WAITOK);
strlcpy(buf, soun->sun_path, namelen + 1);
mtx_lock(&Giant);
restart:
mtx_assert(&Giant, MA_OWNED);
NDINIT(&nd, CREATE, NOFOLLOW | LOCKPARENT | SAVENAME, UIO_SYSSPACE,
buf, td);
/* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */
error = namei(&nd);
if (error)
goto done;
vp = nd.ni_vp;
if (vp != NULL || vn_start_write(nd.ni_dvp, &mp, V_NOWAIT) != 0) {
NDFREE(&nd, NDF_ONLY_PNBUF);
if (nd.ni_dvp == vp)
vrele(nd.ni_dvp);
else
vput(nd.ni_dvp);
if (vp != NULL) {
vrele(vp);
error = EADDRINUSE;
goto done;
}
error = vn_start_write(NULL, &mp, V_XSLEEP | PCATCH);
if (error)
goto done;
goto restart;
}
VATTR_NULL(&vattr);
vattr.va_type = VSOCK;
vattr.va_mode = (ACCESSPERMS & ~td->td_proc->p_fd->fd_cmask);
#ifdef MAC
error = mac_check_vnode_create(td->td_ucred, nd.ni_dvp, &nd.ni_cnd,
&vattr);
#endif
if (error == 0) {
VOP_LEASE(nd.ni_dvp, td, td->td_ucred, LEASE_WRITE);
error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr);
}
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(nd.ni_dvp);
if (error) {
vn_finished_write(mp);
goto done;
}
vp = nd.ni_vp;
ASSERT_VOP_LOCKED(vp, "unp_bind");
soun = (struct sockaddr_un *)sodupsockaddr(nam, M_WAITOK);
UNP_LOCK();
vp->v_socket = unp->unp_socket;
unp->unp_vnode = vp;
unp->unp_addr = soun;
UNP_UNLOCK();
VOP_UNLOCK(vp, 0, td);
vn_finished_write(mp);
done:
mtx_unlock(&Giant);
free(buf, M_TEMP);
UNP_LOCK();
return (error);
}
static int
unp_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
{
struct sockaddr_un *soun = (struct sockaddr_un *)nam;
struct vnode *vp;
struct socket *so2, *so3;
struct unpcb *unp, *unp2, *unp3;
int error, len;
struct nameidata nd;
char buf[SOCK_MAXADDRLEN];
struct sockaddr *sa;
UNP_LOCK_ASSERT();
unp = sotounpcb(so);
len = nam->sa_len - offsetof(struct sockaddr_un, sun_path);
if (len <= 0)
return (EINVAL);
strlcpy(buf, soun->sun_path, len + 1);
UNP_UNLOCK();
sa = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
mtx_lock(&Giant);
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, buf, td);
error = namei(&nd);
if (error)
vp = NULL;
else
vp = nd.ni_vp;
ASSERT_VOP_LOCKED(vp, "unp_connect");
NDFREE(&nd, NDF_ONLY_PNBUF);
if (error)
goto bad;
if (vp->v_type != VSOCK) {
error = ENOTSOCK;
goto bad;
}
error = VOP_ACCESS(vp, VWRITE, td->td_ucred, td);
if (error)
goto bad;
mtx_unlock(&Giant);
UNP_LOCK();
unp = sotounpcb(so);
if (unp == NULL) {
error = EINVAL;
goto bad2;
}
so2 = vp->v_socket;
if (so2 == NULL) {
error = ECONNREFUSED;
goto bad2;
}
if (so->so_type != so2->so_type) {
error = EPROTOTYPE;
goto bad2;
}
if (so->so_proto->pr_flags & PR_CONNREQUIRED) {
if (so2->so_options & SO_ACCEPTCONN) {
/*
* NB: drop locks here so unp_attach is entered
* w/o locks; this avoids a recursive lock
* of the head and holding sleep locks across
* a (potentially) blocking malloc.
*/
UNP_UNLOCK();
so3 = sonewconn(so2, 0);
UNP_LOCK();
} else
so3 = NULL;
if (so3 == NULL) {
error = ECONNREFUSED;
goto bad2;
}
unp = sotounpcb(so);
unp2 = sotounpcb(so2);
unp3 = sotounpcb(so3);
if (unp2->unp_addr != NULL) {
bcopy(unp2->unp_addr, sa, unp2->unp_addr->sun_len);
unp3->unp_addr = (struct sockaddr_un *) sa;
sa = NULL;
}
/*
* unp_peercred management:
*
* The connecter's (client's) credentials are copied
* from its process structure at the time of connect()
* (which is now).
*/
cru2x(td->td_ucred, &unp3->unp_peercred);
unp3->unp_flags |= UNP_HAVEPC;
/*
* The receiver's (server's) credentials are copied
* from the unp_peercred member of socket on which the
* former called listen(); unp_listen() cached that
* process's credentials at that time so we can use
* them now.
*/
KASSERT(unp2->unp_flags & UNP_HAVEPCCACHED,
("unp_connect: listener without cached peercred"));
memcpy(&unp->unp_peercred, &unp2->unp_peercred,
sizeof(unp->unp_peercred));
unp->unp_flags |= UNP_HAVEPC;
#ifdef MAC
SOCK_LOCK(so);
mac_set_socket_peer_from_socket(so, so3);
mac_set_socket_peer_from_socket(so3, so);
SOCK_UNLOCK(so);
#endif
so2 = so3;
}
error = unp_connect2(so, so2, PRU_CONNECT);
bad2:
UNP_UNLOCK();
mtx_lock(&Giant);
bad:
mtx_assert(&Giant, MA_OWNED);
if (vp != NULL)
vput(vp);
mtx_unlock(&Giant);
free(sa, M_SONAME);
UNP_LOCK();
return (error);
}
static int
unp_connect2(struct socket *so, struct socket *so2, int req)
{
struct unpcb *unp = sotounpcb(so);
struct unpcb *unp2;
UNP_LOCK_ASSERT();
if (so2->so_type != so->so_type)
return (EPROTOTYPE);
unp2 = sotounpcb(so2);
unp->unp_conn = unp2;
switch (so->so_type) {
case SOCK_DGRAM:
LIST_INSERT_HEAD(&unp2->unp_refs, unp, unp_reflink);
soisconnected(so);
break;
case SOCK_STREAM:
unp2->unp_conn = unp;
if (req == PRU_CONNECT &&
((unp->unp_flags | unp2->unp_flags) & UNP_CONNWAIT))
soisconnecting(so);
else
soisconnected(so);
soisconnected(so2);
break;
default:
panic("unp_connect2");
}
return (0);
}
static void
unp_disconnect(struct unpcb *unp)
{
struct unpcb *unp2 = unp->unp_conn;
struct socket *so;
UNP_LOCK_ASSERT();
if (unp2 == NULL)
return;
unp->unp_conn = NULL;
switch (unp->unp_socket->so_type) {
case SOCK_DGRAM:
LIST_REMOVE(unp, unp_reflink);
so = unp->unp_socket;
SOCK_LOCK(so);
so->so_state &= ~SS_ISCONNECTED;
SOCK_UNLOCK(so);
break;
case SOCK_STREAM:
soisdisconnected(unp->unp_socket);
unp2->unp_conn = NULL;
soisdisconnected(unp2->unp_socket);
break;
}
}
#ifdef notdef
void
unp_abort(struct unpcb *unp)
{
unp_detach(unp);
UNP_UNLOCK_ASSERT();
}
#endif
/*
* unp_pcblist() assumes that UNIX domain socket memory is never reclaimed
* by the zone (UMA_ZONE_NOFREE), and as such potentially stale pointers
* are safe to reference. It first scans the list of struct unpcb's to
* generate a pointer list, then it rescans its list one entry at a time to
* externalize and copyout. It checks the generation number to see if a
* struct unpcb has been reused, and will skip it if so.
*/
static int
unp_pcblist(SYSCTL_HANDLER_ARGS)
{
int error, i, n;
struct unpcb *unp, **unp_list;
unp_gen_t gencnt;
struct xunpgen *xug;
struct unp_head *head;
struct xunpcb *xu;
head = ((intptr_t)arg1 == SOCK_DGRAM ? &unp_dhead : &unp_shead);
/*
* The process of preparing the PCB list is too time-consuming and
* resource-intensive to repeat twice on every request.
*/
if (req->oldptr == NULL) {
n = unp_count;
req->oldidx = 2 * (sizeof *xug)
+ (n + n/8) * sizeof(struct xunpcb);
return (0);
}
if (req->newptr != NULL)
return (EPERM);
/*
* OK, now we're committed to doing something.
*/
xug = malloc(sizeof(*xug), M_TEMP, M_WAITOK);
UNP_LOCK();
gencnt = unp_gencnt;
n = unp_count;
UNP_UNLOCK();
xug->xug_len = sizeof *xug;
xug->xug_count = n;
xug->xug_gen = gencnt;
xug->xug_sogen = so_gencnt;
error = SYSCTL_OUT(req, xug, sizeof *xug);
if (error) {
free(xug, M_TEMP);
return (error);
}
unp_list = malloc(n * sizeof *unp_list, M_TEMP, M_WAITOK);
UNP_LOCK();
for (unp = LIST_FIRST(head), i = 0; unp && i < n;
unp = LIST_NEXT(unp, unp_link)) {
if (unp->unp_gencnt <= gencnt) {
if (cr_cansee(req->td->td_ucred,
unp->unp_socket->so_cred))
continue;
unp_list[i++] = unp;
}
}
UNP_UNLOCK();
n = i; /* in case we lost some during malloc */
error = 0;
xu = malloc(sizeof(*xu), M_TEMP, M_WAITOK | M_ZERO);
for (i = 0; i < n; i++) {
unp = unp_list[i];
if (unp->unp_gencnt <= gencnt) {
xu->xu_len = sizeof *xu;
xu->xu_unpp = unp;
/*
* XXX - need more locking here to protect against
* connect/disconnect races for SMP.
*/
if (unp->unp_addr != NULL)
bcopy(unp->unp_addr, &xu->xu_addr,
unp->unp_addr->sun_len);
if (unp->unp_conn != NULL &&
unp->unp_conn->unp_addr != NULL)
bcopy(unp->unp_conn->unp_addr,
&xu->xu_caddr,
unp->unp_conn->unp_addr->sun_len);
bcopy(unp, &xu->xu_unp, sizeof *unp);
sotoxsocket(unp->unp_socket, &xu->xu_socket);
error = SYSCTL_OUT(req, xu, sizeof *xu);
}
}
free(xu, M_TEMP);
if (!error) {
/*
* Give the user an updated idea of our state.
* If the generation differs from what we told
* her before, she knows that something happened
* while we were processing this request, and it
* might be necessary to retry.
*/
xug->xug_gen = unp_gencnt;
xug->xug_sogen = so_gencnt;
xug->xug_count = unp_count;
error = SYSCTL_OUT(req, xug, sizeof *xug);
}
free(unp_list, M_TEMP);
free(xug, M_TEMP);
return (error);
}
SYSCTL_PROC(_net_local_dgram, OID_AUTO, pcblist, CTLFLAG_RD,
(caddr_t)(long)SOCK_DGRAM, 0, unp_pcblist, "S,xunpcb",
"List of active local datagram sockets");
SYSCTL_PROC(_net_local_stream, OID_AUTO, pcblist, CTLFLAG_RD,
(caddr_t)(long)SOCK_STREAM, 0, unp_pcblist, "S,xunpcb",
"List of active local stream sockets");
static void
unp_shutdown(struct unpcb *unp)
{
struct socket *so;
UNP_LOCK_ASSERT();
if (unp->unp_socket->so_type == SOCK_STREAM && unp->unp_conn &&
(so = unp->unp_conn->unp_socket))
socantrcvmore(so);
}
static void
unp_drop(struct unpcb *unp, int errno)
{
struct socket *so = unp->unp_socket;
UNP_LOCK_ASSERT();
so->so_error = errno;
unp_disconnect(unp);
}
#ifdef notdef
void
unp_drain(void)
{
}
#endif
static void
unp_freerights(struct file **rp, int fdcount)
{
int i;
struct file *fp;
for (i = 0; i < fdcount; i++) {
fp = *rp;
/*
* zero the pointer before calling
* unp_discard since it may end up
* in unp_gc()..
*/
*rp++ = 0;
unp_discard(fp);
}
}
int
unp_externalize(struct mbuf *control, struct mbuf **controlp)
{
struct thread *td = curthread; /* XXX */
struct cmsghdr *cm = mtod(control, struct cmsghdr *);
int i;
int *fdp;
struct file **rp;
struct file *fp;
void *data;
socklen_t clen = control->m_len, datalen;
int error, newfds;
int f;
u_int newlen;
UNP_UNLOCK_ASSERT();
error = 0;
if (controlp != NULL) /* controlp == NULL => free control messages */
*controlp = NULL;
while (cm != NULL) {
if (sizeof(*cm) > clen || cm->cmsg_len > clen) {
error = EINVAL;
break;
}
data = CMSG_DATA(cm);
datalen = (caddr_t)cm + cm->cmsg_len - (caddr_t)data;
if (cm->cmsg_level == SOL_SOCKET
&& cm->cmsg_type == SCM_RIGHTS) {
newfds = datalen / sizeof(struct file *);
rp = data;
/* If we're not outputting the descriptors free them. */
if (error || controlp == NULL) {
unp_freerights(rp, newfds);
goto next;
}
FILEDESC_LOCK(td->td_proc->p_fd);
/* if the new FD's will not fit free them. */
if (!fdavail(td, newfds)) {
FILEDESC_UNLOCK(td->td_proc->p_fd);
error = EMSGSIZE;
unp_freerights(rp, newfds);
goto next;
}
/*
* now change each pointer to an fd in the global
* table to an integer that is the index to the
* local fd table entry that we set up to point
* to the global one we are transferring.
*/
newlen = newfds * sizeof(int);
*controlp = sbcreatecontrol(NULL, newlen,
SCM_RIGHTS, SOL_SOCKET);
if (*controlp == NULL) {
FILEDESC_UNLOCK(td->td_proc->p_fd);
error = E2BIG;
unp_freerights(rp, newfds);
goto next;
}
fdp = (int *)
CMSG_DATA(mtod(*controlp, struct cmsghdr *));
for (i = 0; i < newfds; i++) {
if (fdalloc(td, 0, &f))
panic("unp_externalize fdalloc failed");
fp = *rp++;
td->td_proc->p_fd->fd_ofiles[f] = fp;
FILE_LOCK(fp);
fp->f_msgcount--;
FILE_UNLOCK(fp);
unp_rights--;
*fdp++ = f;
}
FILEDESC_UNLOCK(td->td_proc->p_fd);
} else { /* We can just copy anything else across */
if (error || controlp == NULL)
goto next;
*controlp = sbcreatecontrol(NULL, datalen,
cm->cmsg_type, cm->cmsg_level);
if (*controlp == NULL) {
error = ENOBUFS;
goto next;
}
bcopy(data,
CMSG_DATA(mtod(*controlp, struct cmsghdr *)),
datalen);
}
controlp = &(*controlp)->m_next;
next:
if (CMSG_SPACE(datalen) < clen) {
clen -= CMSG_SPACE(datalen);
cm = (struct cmsghdr *)
((caddr_t)cm + CMSG_SPACE(datalen));
} else {
clen = 0;
cm = NULL;
}
}
m_freem(control);
return (error);
}
void
unp_init(void)
{
unp_zone = uma_zcreate("unpcb", sizeof(struct unpcb), NULL, NULL,
NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
if (unp_zone == NULL)
panic("unp_init");
uma_zone_set_max(unp_zone, nmbclusters);
LIST_INIT(&unp_dhead);
LIST_INIT(&unp_shead);
TASK_INIT(&unp_gc_task, 0, unp_gc, NULL);
UNP_LOCK_INIT();
}
static int
unp_internalize(struct mbuf **controlp, struct thread *td)
{
struct mbuf *control = *controlp;
struct proc *p = td->td_proc;
struct filedesc *fdescp = p->p_fd;
struct cmsghdr *cm = mtod(control, struct cmsghdr *);
struct cmsgcred *cmcred;
struct file **rp;
struct file *fp;
struct timeval *tv;
int i, fd, *fdp;
void *data;
socklen_t clen = control->m_len, datalen;
int error, oldfds;
u_int newlen;
UNP_UNLOCK_ASSERT();
error = 0;
*controlp = NULL;
while (cm != NULL) {
if (sizeof(*cm) > clen || cm->cmsg_level != SOL_SOCKET
|| cm->cmsg_len > clen) {
error = EINVAL;
goto out;
}
data = CMSG_DATA(cm);
datalen = (caddr_t)cm + cm->cmsg_len - (caddr_t)data;
switch (cm->cmsg_type) {
/*
* Fill in credential information.
*/
case SCM_CREDS:
*controlp = sbcreatecontrol(NULL, sizeof(*cmcred),
SCM_CREDS, SOL_SOCKET);
if (*controlp == NULL) {
error = ENOBUFS;
goto out;
}
cmcred = (struct cmsgcred *)
CMSG_DATA(mtod(*controlp, struct cmsghdr *));
cmcred->cmcred_pid = p->p_pid;
cmcred->cmcred_uid = td->td_ucred->cr_ruid;
cmcred->cmcred_gid = td->td_ucred->cr_rgid;
cmcred->cmcred_euid = td->td_ucred->cr_uid;
cmcred->cmcred_ngroups = MIN(td->td_ucred->cr_ngroups,
CMGROUP_MAX);
for (i = 0; i < cmcred->cmcred_ngroups; i++)
cmcred->cmcred_groups[i] =
td->td_ucred->cr_groups[i];
break;
case SCM_RIGHTS:
oldfds = datalen / sizeof (int);
/*
* check that all the FDs passed in refer to legal files
* If not, reject the entire operation.
*/
fdp = data;
FILEDESC_LOCK(fdescp);
for (i = 0; i < oldfds; i++) {
fd = *fdp++;
if ((unsigned)fd >= fdescp->fd_nfiles ||
fdescp->fd_ofiles[fd] == NULL) {
FILEDESC_UNLOCK(fdescp);
error = EBADF;
goto out;
}
fp = fdescp->fd_ofiles[fd];
if (!(fp->f_ops->fo_flags & DFLAG_PASSABLE)) {
FILEDESC_UNLOCK(fdescp);
error = EOPNOTSUPP;
goto out;
}
}
/*
* Now replace the integer FDs with pointers to
* the associated global file table entry..
*/
newlen = oldfds * sizeof(struct file *);
*controlp = sbcreatecontrol(NULL, newlen,
SCM_RIGHTS, SOL_SOCKET);
if (*controlp == NULL) {
FILEDESC_UNLOCK(fdescp);
error = E2BIG;
goto out;
}
fdp = data;
rp = (struct file **)
CMSG_DATA(mtod(*controlp, struct cmsghdr *));
for (i = 0; i < oldfds; i++) {
fp = fdescp->fd_ofiles[*fdp++];
*rp++ = fp;
FILE_LOCK(fp);
fp->f_count++;
fp->f_msgcount++;
FILE_UNLOCK(fp);
unp_rights++;
}
FILEDESC_UNLOCK(fdescp);
break;
case SCM_TIMESTAMP:
*controlp = sbcreatecontrol(NULL, sizeof(*tv),
SCM_TIMESTAMP, SOL_SOCKET);
if (*controlp == NULL) {
error = ENOBUFS;
goto out;
}
tv = (struct timeval *)
CMSG_DATA(mtod(*controlp, struct cmsghdr *));
microtime(tv);
break;
default:
error = EINVAL;
goto out;
}
controlp = &(*controlp)->m_next;
if (CMSG_SPACE(datalen) < clen) {
clen -= CMSG_SPACE(datalen);
cm = (struct cmsghdr *)
((caddr_t)cm + CMSG_SPACE(datalen));
} else {
clen = 0;
cm = NULL;
}
}
out:
m_freem(control);
return (error);
}
struct mbuf *
unp_addsockcred(struct thread *td, struct mbuf *control)
{
struct mbuf *m, *n;
struct sockcred *sc;
int ngroups;
int i;
ngroups = MIN(td->td_ucred->cr_ngroups, CMGROUP_MAX);
m = sbcreatecontrol(NULL, SOCKCREDSIZE(ngroups), SCM_CREDS, SOL_SOCKET);
if (m == NULL)
return (control);
m->m_next = NULL;
sc = (struct sockcred *) CMSG_DATA(mtod(m, struct cmsghdr *));
sc->sc_uid = td->td_ucred->cr_ruid;
sc->sc_euid = td->td_ucred->cr_uid;
sc->sc_gid = td->td_ucred->cr_rgid;
sc->sc_egid = td->td_ucred->cr_gid;
sc->sc_ngroups = ngroups;
for (i = 0; i < sc->sc_ngroups; i++)
sc->sc_groups[i] = td->td_ucred->cr_groups[i];
/*
* If a control message already exists, append us to the end.
*/
if (control != NULL) {
for (n = control; n->m_next != NULL; n = n->m_next)
;
n->m_next = m;
} else
control = m;
return (control);
}
/*
* unp_defer indicates whether additional work has been defered for a future
* pass through unp_gc(). It is thread local and does not require explicit
* synchronization.
*/
static int unp_defer;
static int unp_taskcount;
SYSCTL_INT(_net_local, OID_AUTO, taskcount, CTLFLAG_RD, &unp_taskcount, 0, "");
static int unp_recycled;
SYSCTL_INT(_net_local, OID_AUTO, recycled, CTLFLAG_RD, &unp_recycled, 0, "");
static void
unp_gc(__unused void *arg, int pending)
{
struct file *fp, *nextfp;
struct socket *so;
struct file **extra_ref, **fpp;
int nunref, i;
int nfiles_snap;
int nfiles_slack = 20;
unp_taskcount++;
unp_defer = 0;
/*
* before going through all this, set all FDs to
* be NOT defered and NOT externally accessible
*/
sx_slock(&filelist_lock);
LIST_FOREACH(fp, &filehead, f_list)
fp->f_gcflag &= ~(FMARK|FDEFER);
do {
KASSERT(unp_defer >= 0, ("unp_gc: unp_defer %d", unp_defer));
LIST_FOREACH(fp, &filehead, f_list) {
FILE_LOCK(fp);
/*
* If the file is not open, skip it -- could be a
* file in the process of being opened, or in the
* process of being closed. If the file is
* "closing", it may have been marked for deferred
* consideration. Clear the flag now if so.
*/
if (fp->f_count == 0) {
if (fp->f_gcflag & FDEFER)
unp_defer--;
fp->f_gcflag &= ~(FMARK|FDEFER);
FILE_UNLOCK(fp);
continue;
}
/*
* If we already marked it as 'defer' in a
* previous pass, then try process it this time
* and un-mark it
*/
if (fp->f_gcflag & FDEFER) {
fp->f_gcflag &= ~FDEFER;
unp_defer--;
} else {
/*
* if it's not defered, then check if it's
* already marked.. if so skip it
*/
if (fp->f_gcflag & FMARK) {
FILE_UNLOCK(fp);
continue;
}
/*
* If all references are from messages
* in transit, then skip it. it's not
* externally accessible.
*/
if (fp->f_count == fp->f_msgcount) {
FILE_UNLOCK(fp);
continue;
}
/*
* If it got this far then it must be
* externally accessible.
*/
fp->f_gcflag |= FMARK;
}
/*
* either it was defered, or it is externally
* accessible and not already marked so.
* Now check if it is possibly one of OUR sockets.
*/
if (fp->f_type != DTYPE_SOCKET ||
(so = fp->f_data) == NULL) {
FILE_UNLOCK(fp);
continue;
}
FILE_UNLOCK(fp);
if (so->so_proto->pr_domain != &localdomain ||
(so->so_proto->pr_flags&PR_RIGHTS) == 0)
continue;
/*
* So, Ok, it's one of our sockets and it IS externally
* accessible (or was defered). Now we look
* to see if we hold any file descriptors in its
* message buffers. Follow those links and mark them
* as accessible too.
*/
SOCKBUF_LOCK(&so->so_rcv);
unp_scan(so->so_rcv.sb_mb, unp_mark);
SOCKBUF_UNLOCK(&so->so_rcv);
}
} while (unp_defer);
sx_sunlock(&filelist_lock);
/*
* XXXRW: The following comments need updating for a post-SMPng and
* deferred unp_gc() world, but are still generally accurate.
*
* We grab an extra reference to each of the file table entries
* that are not otherwise accessible and then free the rights
* that are stored in messages on them.
*
* The bug in the orginal code is a little tricky, so I'll describe
* what's wrong with it here.
*
* It is incorrect to simply unp_discard each entry for f_msgcount
* times -- consider the case of sockets A and B that contain
* references to each other. On a last close of some other socket,
* we trigger a gc since the number of outstanding rights (unp_rights)
* is non-zero. If during the sweep phase the gc code unp_discards,
* we end up doing a (full) closef on the descriptor. A closef on A
* results in the following chain. Closef calls soo_close, which
* calls soclose. Soclose calls first (through the switch
* uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply
* returns because the previous instance had set unp_gcing, and
* we return all the way back to soclose, which marks the socket
* with SS_NOFDREF, and then calls sofree. Sofree calls sorflush
* to free up the rights that are queued in messages on the socket A,
* i.e., the reference on B. The sorflush calls via the dom_dispose
* switch unp_dispose, which unp_scans with unp_discard. This second
* instance of unp_discard just calls closef on B.
*
* Well, a similar chain occurs on B, resulting in a sorflush on B,
* which results in another closef on A. Unfortunately, A is already
* being closed, and the descriptor has already been marked with
* SS_NOFDREF, and soclose panics at this point.
*
* Here, we first take an extra reference to each inaccessible
* descriptor. Then, we call sorflush ourself, since we know
* it is a Unix domain socket anyhow. After we destroy all the
* rights carried in messages, we do a last closef to get rid
* of our extra reference. This is the last close, and the
* unp_detach etc will shut down the socket.
*
* 91/09/19, bsy@cs.cmu.edu
*/
again:
nfiles_snap = openfiles + nfiles_slack; /* some slack */
extra_ref = malloc(nfiles_snap * sizeof(struct file *), M_TEMP,
M_WAITOK);
sx_slock(&filelist_lock);
if (nfiles_snap < openfiles) {
sx_sunlock(&filelist_lock);
free(extra_ref, M_TEMP);
nfiles_slack += 20;
goto again;
}
for (nunref = 0, fp = LIST_FIRST(&filehead), fpp = extra_ref;
fp != NULL; fp = nextfp) {
nextfp = LIST_NEXT(fp, f_list);
FILE_LOCK(fp);
/*
* If it's not open, skip it
*/
if (fp->f_count == 0) {
FILE_UNLOCK(fp);
continue;
}
/*
* If all refs are from msgs, and it's not marked accessible
* then it must be referenced from some unreachable cycle
* of (shut-down) FDs, so include it in our
* list of FDs to remove
*/
if (fp->f_count == fp->f_msgcount && !(fp->f_gcflag & FMARK)) {
*fpp++ = fp;
nunref++;
fp->f_count++;
}
FILE_UNLOCK(fp);
}
sx_sunlock(&filelist_lock);
/*
* for each FD on our hit list, do the following two things
*/
for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) {
struct file *tfp = *fpp;
FILE_LOCK(tfp);
if (tfp->f_type == DTYPE_SOCKET &&
tfp->f_data != NULL) {
FILE_UNLOCK(tfp);
sorflush(tfp->f_data);
} else {
FILE_UNLOCK(tfp);
}
}
for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) {
closef(*fpp, (struct thread *) NULL);
unp_recycled++;
}
free(extra_ref, M_TEMP);
}
void
unp_dispose(struct mbuf *m)
{
if (m)
unp_scan(m, unp_discard);
}
static int
unp_listen(struct socket *so, struct unpcb *unp, int backlog,
struct thread *td)
{
int error;
UNP_LOCK_ASSERT();
SOCK_LOCK(so);
error = solisten_proto_check(so);
if (error == 0) {
cru2x(td->td_ucred, &unp->unp_peercred);
unp->unp_flags |= UNP_HAVEPCCACHED;
solisten_proto(so, backlog);
}
SOCK_UNLOCK(so);
return (error);
}
static void
unp_scan(struct mbuf *m0, void (*op)(struct file *))
{
struct mbuf *m;
struct file **rp;
struct cmsghdr *cm;
void *data;
int i;
socklen_t clen, datalen;
int qfds;
while (m0 != NULL) {
for (m = m0; m; m = m->m_next) {
if (m->m_type != MT_CONTROL)
continue;
cm = mtod(m, struct cmsghdr *);
clen = m->m_len;
while (cm != NULL) {
if (sizeof(*cm) > clen || cm->cmsg_len > clen)
break;
data = CMSG_DATA(cm);
datalen = (caddr_t)cm + cm->cmsg_len
- (caddr_t)data;
if (cm->cmsg_level == SOL_SOCKET &&
cm->cmsg_type == SCM_RIGHTS) {
qfds = datalen / sizeof (struct file *);
rp = data;
for (i = 0; i < qfds; i++)
(*op)(*rp++);
}
if (CMSG_SPACE(datalen) < clen) {
clen -= CMSG_SPACE(datalen);
cm = (struct cmsghdr *)
((caddr_t)cm + CMSG_SPACE(datalen));
} else {
clen = 0;
cm = NULL;
}
}
}
m0 = m0->m_act;
}
}
static void
unp_mark(struct file *fp)
{
if (fp->f_gcflag & FMARK)
return;
unp_defer++;
fp->f_gcflag |= (FMARK|FDEFER);
}
static void
unp_discard(struct file *fp)
{
UNP_LOCK();
FILE_LOCK(fp);
fp->f_msgcount--;
unp_rights--;
FILE_UNLOCK(fp);
UNP_UNLOCK();
(void) closef(fp, (struct thread *)NULL);
}
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