IABSD.fr/src/sys/kern/uipc_usrreq.c

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• Author : bluhm
  Date : 2019-07-16 21:41:37
  Hash : bb127fc6
  Message : Fix uipc white spaces.

• sys/kern/uipc_usrreq.c

• /*	$OpenBSD: uipc_usrreq.c,v 1.142 2019/07/16 21:41:37 bluhm Exp $	*/
  /*	$NetBSD: uipc_usrreq.c,v 1.18 1996/02/09 19:00:50 christos Exp $	*/
  
  /*
   * Copyright (c) 1982, 1986, 1989, 1991, 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.
   *
   *	@(#)uipc_usrreq.c	8.3 (Berkeley) 1/4/94
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/proc.h>
  #include <sys/filedesc.h>
  #include <sys/domain.h>
  #include <sys/protosw.h>
  #include <sys/queue.h>
  #include <sys/socket.h>
  #include <sys/socketvar.h>
  #include <sys/unpcb.h>
  #include <sys/un.h>
  #include <sys/namei.h>
  #include <sys/vnode.h>
  #include <sys/file.h>
  #include <sys/stat.h>
  #include <sys/mbuf.h>
  #include <sys/task.h>
  #include <sys/pledge.h>
  #include <sys/pool.h>
  
  void	uipc_setaddr(const struct unpcb *, struct mbuf *);
  
  /* list of all UNIX domain sockets, for unp_gc() */
  LIST_HEAD(unp_head, unpcb) unp_head = LIST_HEAD_INITIALIZER(unp_head);
  
  /*
   * Stack of sets of files that were passed over a socket but were
   * not received and need to be closed.
   */
  struct	unp_deferral {
  	SLIST_ENTRY(unp_deferral)	ud_link;
  	int	ud_n;
  	/* followed by ud_n struct fdpass */
  	struct fdpass ud_fp[];
  };
  
  void	unp_discard(struct fdpass *, int);
  void	unp_mark(struct fdpass *, int);
  void	unp_scan(struct mbuf *, void (*)(struct fdpass *, int));
  int	unp_nam2sun(struct mbuf *, struct sockaddr_un **, size_t *);
  
  struct pool unpcb_pool;
  /* list of sets of files that were sent over sockets that are now closed */
  SLIST_HEAD(,unp_deferral) unp_deferred = SLIST_HEAD_INITIALIZER(unp_deferred);
  
  struct task unp_gc_task = TASK_INITIALIZER(unp_gc, NULL);
  
  
  /*
   * Unix communications domain.
   *
   * TODO:
   *	RDM
   *	rethink name space problems
   *	need a proper out-of-band
   */
  struct	sockaddr sun_noname = { sizeof(sun_noname), AF_UNIX };
  ino_t	unp_ino;			/* prototype for fake inode numbers */
  
  void
  unp_init(void)
  {
  	pool_init(&unpcb_pool, sizeof(struct unpcb), 0,
  	    IPL_NONE, 0, "unpcb", NULL);
  }
  
  void
  uipc_setaddr(const struct unpcb *unp, struct mbuf *nam)
  {
  	if (unp != NULL && unp->unp_addr != NULL) {
  		nam->m_len = unp->unp_addr->m_len;
  		memcpy(mtod(nam, caddr_t), mtod(unp->unp_addr, caddr_t),
  		    nam->m_len);
  	} else {
  		nam->m_len = sizeof(sun_noname);
  		memcpy(mtod(nam, struct sockaddr *), &sun_noname,
  		    nam->m_len);
  	}
  }
  
  int
  uipc_usrreq(struct socket *so, int req, struct mbuf *m, struct mbuf *nam,
      struct mbuf *control, struct proc *p)
  {
  	struct unpcb *unp = sotounpcb(so);
  	struct unpcb *unp2;
  	struct socket *so2;
  	int error = 0;
  
  	if (req == PRU_CONTROL)
  		return (EOPNOTSUPP);
  	if (req != PRU_SEND && control && control->m_len) {
  		error = EOPNOTSUPP;
  		goto release;
  	}
  	if (unp == NULL) {
  		error = EINVAL;
  		goto release;
  	}
  
  	NET_ASSERT_UNLOCKED();
  
  	switch (req) {
  
  	case PRU_BIND:
  		error = unp_bind(unp, nam, p);
  		break;
  
  	case PRU_LISTEN:
  		if (unp->unp_vnode == NULL)
  			error = EINVAL;
  		break;
  
  	case PRU_CONNECT:
  		error = unp_connect(so, nam, p);
  		break;
  
  	case PRU_CONNECT2:
  		error = unp_connect2(so, (struct socket *)nam);
  		if (!error) {
  			unp->unp_connid.uid = p->p_ucred->cr_uid;
  			unp->unp_connid.gid = p->p_ucred->cr_gid;
  			unp->unp_connid.pid = p->p_p->ps_pid;
  			unp->unp_flags |= UNP_FEIDS;
  			unp2 = sotounpcb((struct socket *)nam);
  			unp2->unp_connid.uid = p->p_ucred->cr_uid;
  			unp2->unp_connid.gid = p->p_ucred->cr_gid;
  			unp2->unp_connid.pid = p->p_p->ps_pid;
  			unp2->unp_flags |= UNP_FEIDS;
  		}
  		break;
  
  	case PRU_DISCONNECT:
  		unp_disconnect(unp);
  		break;
  
  	case PRU_ACCEPT:
  		/*
  		 * Pass back name of connected socket,
  		 * if it was bound and we are still connected
  		 * (our peer may have closed already!).
  		 */
  		uipc_setaddr(unp->unp_conn, nam);
  		break;
  
  	case PRU_SHUTDOWN:
  		socantsendmore(so);
  		unp_shutdown(unp);
  		break;
  
  	case PRU_RCVD:
  		switch (so->so_type) {
  
  		case SOCK_DGRAM:
  			panic("uipc 1");
  			/*NOTREACHED*/
  
  		case SOCK_STREAM:
  		case SOCK_SEQPACKET:
  			if (unp->unp_conn == NULL)
  				break;
  			so2 = unp->unp_conn->unp_socket;
  			/*
  			 * Adjust backpressure on sender
  			 * and wakeup any waiting to write.
  			 */
  			so2->so_snd.sb_mbcnt = so->so_rcv.sb_mbcnt;
  			so2->so_snd.sb_cc = so->so_rcv.sb_cc;
  			sowwakeup(so2);
  			break;
  
  		default:
  			panic("uipc 2");
  		}
  		break;
  
  	case PRU_SEND:
  		if (control && (error = unp_internalize(control, p)))
  			break;
  		switch (so->so_type) {
  
  		case SOCK_DGRAM: {
  			struct sockaddr *from;
  
  			if (nam) {
  				if (unp->unp_conn) {
  					error = EISCONN;
  					break;
  				}
  				error = unp_connect(so, nam, p);
  				if (error)
  					break;
  			} else {
  				if (unp->unp_conn == NULL) {
  					error = ENOTCONN;
  					break;
  				}
  			}
  			so2 = unp->unp_conn->unp_socket;
  			if (unp->unp_addr)
  				from = mtod(unp->unp_addr, struct sockaddr *);
  			else
  				from = &sun_noname;
  			if (sbappendaddr(so2, &so2->so_rcv, from, m, control)) {
  				sorwakeup(so2);
  				m = NULL;
  				control = NULL;
  			} else
  				error = ENOBUFS;
  			if (nam)
  				unp_disconnect(unp);
  			break;
  		}
  
  		case SOCK_STREAM:
  		case SOCK_SEQPACKET:
  			if (so->so_state & SS_CANTSENDMORE) {
  				error = EPIPE;
  				break;
  			}
  			if (unp->unp_conn == NULL) {
  				error = ENOTCONN;
  				break;
  			}
  			so2 = unp->unp_conn->unp_socket;
  			/*
  			 * Send to paired receive port, and then raise
  			 * send buffer counts to maintain backpressure.
  			 * Wake up readers.
  			 */
  			if (control) {
  				if (sbappendcontrol(so2, &so2->so_rcv, m,
  				    control)) {
  					control = NULL;
  				} else {
  					error = ENOBUFS;
  					break;
  				}
  			} else if (so->so_type == SOCK_SEQPACKET)
  				sbappendrecord(so2, &so2->so_rcv, m);
  			else
  				sbappend(so2, &so2->so_rcv, m);
  			so->so_snd.sb_mbcnt = so2->so_rcv.sb_mbcnt;
  			so->so_snd.sb_cc = so2->so_rcv.sb_cc;
  			if (so2->so_rcv.sb_cc > 0)
  				sorwakeup(so2);
  			m = NULL;
  			break;
  
  		default:
  			panic("uipc 4");
  		}
  		/* we need to undo unp_internalize in case of errors */
  		if (control && error)
  			unp_dispose(control);
  		break;
  
  	case PRU_ABORT:
  		unp_drop(unp, ECONNABORTED);
  		break;
  
  	case PRU_SENSE: {
  		struct stat *sb = (struct stat *)m;
  
  		sb->st_blksize = so->so_snd.sb_hiwat;
  		sb->st_dev = NODEV;
  		if (unp->unp_ino == 0)
  			unp->unp_ino = unp_ino++;
  		sb->st_atim.tv_sec =
  		    sb->st_mtim.tv_sec =
  		    sb->st_ctim.tv_sec = unp->unp_ctime.tv_sec;
  		sb->st_atim.tv_nsec =
  		    sb->st_mtim.tv_nsec =
  		    sb->st_ctim.tv_nsec = unp->unp_ctime.tv_nsec;
  		sb->st_ino = unp->unp_ino;
  		break;
  	}
  
  	case PRU_RCVOOB:
  	case PRU_SENDOOB:
  		error = EOPNOTSUPP;
  		break;
  
  	case PRU_SOCKADDR:
  		uipc_setaddr(unp, nam);
  		break;
  
  	case PRU_PEERADDR:
  		uipc_setaddr(unp->unp_conn, nam);
  		break;
  
  	case PRU_SLOWTIMO:
  		break;
  
  	default:
  		panic("uipc_usrreq");
  	}
  release:
  	if (req != PRU_RCVD && req != PRU_RCVOOB && req != PRU_SENSE) {
  		m_freem(control);
  		m_freem(m);
  	}
  	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.
   */
  #define	PIPSIZ	4096
  u_long	unpst_sendspace = PIPSIZ;
  u_long	unpst_recvspace = PIPSIZ;
  u_long	unpdg_sendspace = 2*1024;	/* really max datagram size */
  u_long	unpdg_recvspace = 4*1024;
  
  int	unp_rights;			/* file descriptors in flight */
  
  int
  uipc_attach(struct socket *so, int proto)
  {
  	struct unpcb *unp;
  	int error;
  
  	if (so->so_pcb)
  		return EISCONN;
  	if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
  		switch (so->so_type) {
  
  		case SOCK_STREAM:
  		case SOCK_SEQPACKET:
  			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 = pool_get(&unpcb_pool, PR_NOWAIT|PR_ZERO);
  	if (unp == NULL)
  		return (ENOBUFS);
  	unp->unp_socket = so;
  	so->so_pcb = unp;
  	getnanotime(&unp->unp_ctime);
  	LIST_INSERT_HEAD(&unp_head, unp, unp_link);
  	return (0);
  }
  
  int
  uipc_detach(struct socket *so)
  {
  	struct unpcb *unp = sotounpcb(so);
  
  	if (unp == NULL)
  		return (EINVAL);
  
  	NET_ASSERT_UNLOCKED();
  
  	unp_detach(unp);
  
  	return (0);
  }
  
  void
  unp_detach(struct unpcb *unp)
  {
  	struct vnode *vp;
  
  	LIST_REMOVE(unp, unp_link);
  	if (unp->unp_vnode) {
  		unp->unp_vnode->v_socket = NULL;
  		vp = unp->unp_vnode;
  		unp->unp_vnode = NULL;
  		vrele(vp);
  	}
  	if (unp->unp_conn)
  		unp_disconnect(unp);
  	while (!SLIST_EMPTY(&unp->unp_refs))
  		unp_drop(SLIST_FIRST(&unp->unp_refs), ECONNRESET);
  	soisdisconnected(unp->unp_socket);
  	unp->unp_socket->so_pcb = NULL;
  	m_freem(unp->unp_addr);
  	pool_put(&unpcb_pool, unp);
  	if (unp_rights)
  		task_add(systq, &unp_gc_task);
  }
  
  int
  unp_bind(struct unpcb *unp, struct mbuf *nam, struct proc *p)
  {
  	struct sockaddr_un *soun;
  	struct mbuf *nam2;
  	struct vnode *vp;
  	struct vattr vattr;
  	int error;
  	struct nameidata nd;
  	size_t pathlen;
  
  	if (unp->unp_vnode != NULL)
  		return (EINVAL);
  	if ((error = unp_nam2sun(nam, &soun, &pathlen)))
  		return (error);
  
  	nam2 = m_getclr(M_WAITOK, MT_SONAME);
  	nam2->m_len = sizeof(struct sockaddr_un);
  	memcpy(mtod(nam2, struct sockaddr_un *), soun,
  	    offsetof(struct sockaddr_un, sun_path) + pathlen);
  	/* No need to NUL terminate: m_getclr() returns zero'd mbufs. */
  
  	soun = mtod(nam2, struct sockaddr_un *);
  
  	/* Fixup sun_len to keep it in sync with m_len. */
  	soun->sun_len = nam2->m_len;
  
  	NDINIT(&nd, CREATE, NOFOLLOW | LOCKPARENT, UIO_SYSSPACE,
  	    soun->sun_path, p);
  	nd.ni_pledge = PLEDGE_UNIX;
  /* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */
  	if ((error = namei(&nd)) != 0) {
  		m_freem(nam2);
  		return (error);
  	}
  	vp = nd.ni_vp;
  	if (vp != NULL) {
  		VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
  		if (nd.ni_dvp == vp)
  			vrele(nd.ni_dvp);
  		else
  			vput(nd.ni_dvp);
  		vrele(vp);
  		m_freem(nam2);
  		return (EADDRINUSE);
  	}
  	VATTR_NULL(&vattr);
  	vattr.va_type = VSOCK;
  	vattr.va_mode = ACCESSPERMS &~ p->p_fd->fd_cmask;
  	error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr);
  	vput(nd.ni_dvp);
  	if (error) {
  		m_freem(nam2);
  		return (error);
  	}
  	unp->unp_addr = nam2;
  	vp = nd.ni_vp;
  	vp->v_socket = unp->unp_socket;
  	unp->unp_vnode = vp;
  	unp->unp_connid.uid = p->p_ucred->cr_uid;
  	unp->unp_connid.gid = p->p_ucred->cr_gid;
  	unp->unp_connid.pid = p->p_p->ps_pid;
  	unp->unp_flags |= UNP_FEIDSBIND;
  	VOP_UNLOCK(vp);
  	return (0);
  }
  
  int
  unp_connect(struct socket *so, struct mbuf *nam, struct proc *p)
  {
  	struct sockaddr_un *soun;
  	struct vnode *vp;
  	struct socket *so2, *so3;
  	struct unpcb *unp, *unp2, *unp3;
  	struct nameidata nd;
  	int error;
  
  	if ((error = unp_nam2sun(nam, &soun, NULL)))
  		return (error);
  
  	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, soun->sun_path, p);
  	nd.ni_pledge = PLEDGE_UNIX;
  	if ((error = namei(&nd)) != 0)
  		return (error);
  	vp = nd.ni_vp;
  	if (vp->v_type != VSOCK) {
  		error = ENOTSOCK;
  		goto bad;
  	}
  	if ((error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p)) != 0)
  		goto bad;
  	so2 = vp->v_socket;
  	if (so2 == NULL) {
  		error = ECONNREFUSED;
  		goto bad;
  	}
  	if (so->so_type != so2->so_type) {
  		error = EPROTOTYPE;
  		goto bad;
  	}
  	if (so->so_proto->pr_flags & PR_CONNREQUIRED) {
  		if ((so2->so_options & SO_ACCEPTCONN) == 0 ||
  		    (so3 = sonewconn(so2, 0)) == 0) {
  			error = ECONNREFUSED;
  			goto bad;
  		}
  		unp = sotounpcb(so);
  		unp2 = sotounpcb(so2);
  		unp3 = sotounpcb(so3);
  		if (unp2->unp_addr)
  			unp3->unp_addr =
  			    m_copym(unp2->unp_addr, 0, M_COPYALL, M_NOWAIT);
  		unp3->unp_connid.uid = p->p_ucred->cr_uid;
  		unp3->unp_connid.gid = p->p_ucred->cr_gid;
  		unp3->unp_connid.pid = p->p_p->ps_pid;
  		unp3->unp_flags |= UNP_FEIDS;
  		so2 = so3;
  		if (unp2->unp_flags & UNP_FEIDSBIND) {
  			unp->unp_connid = unp2->unp_connid;
  			unp->unp_flags |= UNP_FEIDS;
  		}
  	}
  	error = unp_connect2(so, so2);
  bad:
  	vput(vp);
  	return (error);
  }
  
  int
  unp_connect2(struct socket *so, struct socket *so2)
  {
  	struct unpcb *unp = sotounpcb(so);
  	struct unpcb *unp2;
  
  	if (so2->so_type != so->so_type)
  		return (EPROTOTYPE);
  	unp2 = sotounpcb(so2);
  	unp->unp_conn = unp2;
  	switch (so->so_type) {
  
  	case SOCK_DGRAM:
  		SLIST_INSERT_HEAD(&unp2->unp_refs, unp, unp_nextref);
  		soisconnected(so);
  		break;
  
  	case SOCK_STREAM:
  	case SOCK_SEQPACKET:
  		unp2->unp_conn = unp;
  		soisconnected(so);
  		soisconnected(so2);
  		break;
  
  	default:
  		panic("unp_connect2");
  	}
  	return (0);
  }
  
  void
  unp_disconnect(struct unpcb *unp)
  {
  	struct unpcb *unp2 = unp->unp_conn;
  
  	if (unp2 == NULL)
  		return;
  	unp->unp_conn = NULL;
  	switch (unp->unp_socket->so_type) {
  
  	case SOCK_DGRAM:
  		SLIST_REMOVE(&unp2->unp_refs, unp, unpcb, unp_nextref);
  		unp->unp_socket->so_state &= ~SS_ISCONNECTED;
  		break;
  
  	case SOCK_STREAM:
  	case SOCK_SEQPACKET:
  		unp->unp_socket->so_snd.sb_mbcnt = 0;
  		unp->unp_socket->so_snd.sb_cc = 0;
  		soisdisconnected(unp->unp_socket);
  		unp2->unp_conn = NULL;
  		unp2->unp_socket->so_snd.sb_mbcnt = 0;
  		unp2->unp_socket->so_snd.sb_cc = 0;
  		soisdisconnected(unp2->unp_socket);
  		break;
  	}
  }
  
  void
  unp_shutdown(struct unpcb *unp)
  {
  	struct socket *so;
  
  	switch (unp->unp_socket->so_type) {
  	case SOCK_STREAM:
  	case SOCK_SEQPACKET:
  		if (unp->unp_conn && (so = unp->unp_conn->unp_socket))
  			socantrcvmore(so);
  		break;
  	default:
  		break;
  	}
  }
  
  void
  unp_drop(struct unpcb *unp, int errno)
  {
  	struct socket *so = unp->unp_socket;
  
  	KERNEL_ASSERT_LOCKED();
  
  	so->so_error = errno;
  	unp_disconnect(unp);
  	if (so->so_head) {
  		so->so_pcb = NULL;
  		/*
  		 * As long as the KERNEL_LOCK() is the default lock for Unix
  		 * sockets, do not release it.
  		 */
  		sofree(so, SL_NOUNLOCK);
  		m_freem(unp->unp_addr);
  		pool_put(&unpcb_pool, unp);
  	}
  }
  
  #ifdef notdef
  unp_drain(void)
  {
  
  }
  #endif
  
  extern	struct domain unixdomain;
  
  static struct unpcb *
  fptounp(struct file *fp)
  {
  	struct socket *so;
  
  	if (fp->f_type != DTYPE_SOCKET)
  		return (NULL);
  	if ((so = fp->f_data) == NULL)
  		return (NULL);
  	if (so->so_proto->pr_domain != &unixdomain)
  		return (NULL);
  	return (sotounpcb(so));
  }
  
  int
  unp_externalize(struct mbuf *rights, socklen_t controllen, int flags)
  {
  	struct proc *p = curproc;		/* XXX */
  	struct cmsghdr *cm = mtod(rights, struct cmsghdr *);
  	struct filedesc *fdp = p->p_fd;
  	int i, *fds = NULL;
  	struct fdpass *rp;
  	struct file *fp;
  	int nfds, error = 0;
  
  	/*
  	 * This code only works because SCM_RIGHTS is the only supported
  	 * control message type on unix sockets. Enforce this here.
  	 */
  	if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET)
  		return EINVAL;
  
  	nfds = (cm->cmsg_len - CMSG_ALIGN(sizeof(*cm))) /
  	    sizeof(struct fdpass);
  	if (controllen < CMSG_ALIGN(sizeof(struct cmsghdr)))
  		controllen = 0;
  	else
  		controllen -= CMSG_ALIGN(sizeof(struct cmsghdr));
  	if (nfds > controllen / sizeof(int)) {
  		error = EMSGSIZE;
  		goto restart;
  	}
  
  	/* Make sure the recipient should be able to see the descriptors.. */
  	rp = (struct fdpass *)CMSG_DATA(cm);
  	for (i = 0; i < nfds; i++) {
  		fp = rp->fp;
  		rp++;
  		error = pledge_recvfd(p, fp);
  		if (error)
  			break;
  
  		/*
  		 * No to block devices.  If passing a directory,
  		 * make sure that it is underneath the root.
  		 */
  		if (fdp->fd_rdir != NULL && fp->f_type == DTYPE_VNODE) {
  			struct vnode *vp = (struct vnode *)fp->f_data;
  
  			if (vp->v_type == VBLK ||
  			    (vp->v_type == VDIR &&
  			    !vn_isunder(vp, fdp->fd_rdir, p))) {
  				error = EPERM;
  				break;
  			}
  		}
  	}
  
  	fds = mallocarray(nfds, sizeof(int), M_TEMP, M_WAITOK);
  
  restart:
  	fdplock(fdp);
  	if (error != 0) {
  		if (nfds > 0) {
  			rp = ((struct fdpass *)CMSG_DATA(cm));
  			unp_discard(rp, nfds);
  		}
  		goto out;
  	}
  
  	/*
  	 * First loop -- allocate file descriptor table slots for the
  	 * new descriptors.
  	 */
  	rp = ((struct fdpass *)CMSG_DATA(cm));
  	for (i = 0; i < nfds; i++) {
  		if ((error = fdalloc(p, 0, &fds[i])) != 0) {
  			/*
  			 * Back out what we've done so far.
  			 */
  			for (--i; i >= 0; i--)
  				fdremove(fdp, fds[i]);
  
  			if (error == ENOSPC) {
  				fdexpand(p);
  				error = 0;
  			} else {
  				/*
  				 * This is the error that has historically
  				 * been returned, and some callers may
  				 * expect it.
  				 */
  				error = EMSGSIZE;
  			}
  			fdpunlock(fdp);
  			goto restart;
  		}
  
  		/*
  		 * Make the slot reference the descriptor so that
  		 * fdalloc() works properly.. We finalize it all
  		 * in the loop below.
  		 */
  		mtx_enter(&fdp->fd_fplock);
  		KASSERT(fdp->fd_ofiles[fds[i]] == NULL);
  		fdp->fd_ofiles[fds[i]] = rp->fp;
  		mtx_leave(&fdp->fd_fplock);
  
  		fdp->fd_ofileflags[fds[i]] = (rp->flags & UF_PLEDGED);
  		if (flags & MSG_CMSG_CLOEXEC)
  			fdp->fd_ofileflags[fds[i]] |= UF_EXCLOSE;
  
  		rp++;
  	}
  
  	/*
  	 * Now that adding them has succeeded, update all of the
  	 * descriptor passing state.
  	 */
  	rp = (struct fdpass *)CMSG_DATA(cm);
  	for (i = 0; i < nfds; i++) {
  		struct unpcb *unp;
  
  		fp = rp->fp;
  		rp++;
  		if ((unp = fptounp(fp)) != NULL)
  			unp->unp_msgcount--;
  		unp_rights--;
  	}
  
  	/*
  	 * Copy temporary array to message and adjust length, in case of
  	 * transition from large struct file pointers to ints.
  	 */
  	memcpy(CMSG_DATA(cm), fds, nfds * sizeof(int));
  	cm->cmsg_len = CMSG_LEN(nfds * sizeof(int));
  	rights->m_len = CMSG_LEN(nfds * sizeof(int));
   out:
  	fdpunlock(fdp);
  	if (fds != NULL)
  		free(fds, M_TEMP, nfds * sizeof(int));
  	return (error);
  }
  
  int
  unp_internalize(struct mbuf *control, struct proc *p)
  {
  	struct filedesc *fdp = p->p_fd;
  	struct cmsghdr *cm = mtod(control, struct cmsghdr *);
  	struct fdpass *rp;
  	struct file *fp;
  	struct unpcb *unp;
  	int i, error;
  	int nfds, *ip, fd, neededspace;
  
  	/*
  	 * Check for two potential msg_controllen values because
  	 * IETF stuck their nose in a place it does not belong.
  	 */
  	if (control->m_len < CMSG_LEN(0) || cm->cmsg_len < CMSG_LEN(0))
  		return (EINVAL);
  	if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET ||
  	    !(cm->cmsg_len == control->m_len ||
  	    control->m_len == CMSG_ALIGN(cm->cmsg_len)))
  		return (EINVAL);
  	nfds = (cm->cmsg_len - CMSG_ALIGN(sizeof(*cm))) / sizeof (int);
  
  	if (unp_rights + nfds > maxfiles / 10)
  		return (EMFILE);
  
  	/* Make sure we have room for the struct file pointers */
  morespace:
  	neededspace = CMSG_SPACE(nfds * sizeof(struct fdpass)) -
  	    control->m_len;
  	if (neededspace > m_trailingspace(control)) {
  		char *tmp;
  		/* if we already have a cluster, the message is just too big */
  		if (control->m_flags & M_EXT)
  			return (E2BIG);
  
  		/* copy cmsg data temporarily out of the mbuf */
  		tmp = malloc(control->m_len, M_TEMP, M_WAITOK);
  		memcpy(tmp, mtod(control, caddr_t), control->m_len);
  
  		/* allocate a cluster and try again */
  		MCLGET(control, M_WAIT);
  		if ((control->m_flags & M_EXT) == 0) {
  			free(tmp, M_TEMP, control->m_len);
  			return (ENOBUFS);       /* allocation failed */
  		}
  
  		/* copy the data back into the cluster */
  		cm = mtod(control, struct cmsghdr *);
  		memcpy(cm, tmp, control->m_len);
  		free(tmp, M_TEMP, control->m_len);
  		goto morespace;
  	}
  
  	/* adjust message & mbuf to note amount of space actually used. */
  	cm->cmsg_len = CMSG_LEN(nfds * sizeof(struct fdpass));
  	control->m_len = CMSG_SPACE(nfds * sizeof(struct fdpass));
  
  	ip = ((int *)CMSG_DATA(cm)) + nfds - 1;
  	rp = ((struct fdpass *)CMSG_DATA(cm)) + nfds - 1;
  	fdplock(fdp);
  	for (i = 0; i < nfds; i++) {
  		memcpy(&fd, ip, sizeof fd);
  		ip--;
  		if ((fp = fd_getfile(fdp, fd)) == NULL) {
  			error = EBADF;
  			goto fail;
  		}
  		if (fp->f_count >= FDUP_MAX_COUNT) {
  			error = EDEADLK;
  			goto fail;
  		}
  		error = pledge_sendfd(p, fp);
  		if (error)
  			goto fail;
  
  		/* kqueue descriptors cannot be copied */
  		if (fp->f_type == DTYPE_KQUEUE) {
  			error = EINVAL;
  			goto fail;
  		}
  		rp->fp = fp;
  		rp->flags = fdp->fd_ofileflags[fd] & UF_PLEDGED;
  		rp--;
  		if ((unp = fptounp(fp)) != NULL) {
  			unp->unp_file = fp;
  			unp->unp_msgcount++;
  		}
  		unp_rights++;
  	}
  	fdpunlock(fdp);
  	return (0);
  fail:
  	fdpunlock(fdp);
  	if (fp != NULL)
  		FRELE(fp, p);
  	/* Back out what we just did. */
  	for ( ; i > 0; i--) {
  		rp++;
  		fp = rp->fp;
  		if ((unp = fptounp(fp)) != NULL)
  			unp->unp_msgcount--;
  		FRELE(fp, p);
  		unp_rights--;
  	}
  
  	return (error);
  }
  
  int	unp_defer, unp_gcing;
  
  void
  unp_gc(void *arg __unused)
  {
  	struct unp_deferral *defer;
  	struct file *fp;
  	struct socket *so;
  	struct unpcb *unp;
  	int nunref, i;
  
  	if (unp_gcing)
  		return;
  	unp_gcing = 1;
  
  	/* close any fds on the deferred list */
  	while ((defer = SLIST_FIRST(&unp_deferred)) != NULL) {
  		SLIST_REMOVE_HEAD(&unp_deferred, ud_link);
  		for (i = 0; i < defer->ud_n; i++) {
  			fp = defer->ud_fp[i].fp;
  			if (fp == NULL)
  				continue;
  			 /* closef() expects a refcount of 2 */
  			FREF(fp);
  			if ((unp = fptounp(fp)) != NULL)
  				unp->unp_msgcount--;
  			unp_rights--;
  			(void) closef(fp, NULL);
  		}
  		free(defer, M_TEMP, sizeof(*defer) +
  		    sizeof(struct fdpass) * defer->ud_n);
  	}
  
  	unp_defer = 0;
  	LIST_FOREACH(unp, &unp_head, unp_link)
  		unp->unp_flags &= ~(UNP_GCMARK | UNP_GCDEFER | UNP_GCDEAD);
  	do {
  		nunref = 0;
  		LIST_FOREACH(unp, &unp_head, unp_link) {
  			fp = unp->unp_file;
  			if (unp->unp_flags & UNP_GCDEFER) {
  				/*
  				 * This socket is referenced by another
  				 * socket which is known to be live,
  				 * so it's certainly live.
  				 */
  				unp->unp_flags &= ~UNP_GCDEFER;
  				unp_defer--;
  			} else if (unp->unp_flags & UNP_GCMARK) {
  				/* marked as live in previous pass */
  				continue;
  			} else if (fp == NULL) {
  				/* not being passed, so can't be in loop */
  			} else if (fp->f_count == 0) {
  				/*
  				 * Already being closed, let normal close
  				 * path take its course
  				 */
  			} else {
  				/*
  				 * Unreferenced by other sockets so far,
  				 * so if all the references (f_count) are
  				 * from passing (unp_msgcount) then this
  				 * socket is prospectively dead
  				 */
  				if (fp->f_count == unp->unp_msgcount) {
  					nunref++;
  					unp->unp_flags |= UNP_GCDEAD;
  					continue;
  				}
  			}
  
  			/*
  			 * This is the first time we've seen this socket on
  			 * the mark pass and known it has a live reference,
  			 * so mark it, then scan its receive buffer for
  			 * sockets and note them as deferred (== referenced,
  			 * but not yet marked).
  			 */
  			unp->unp_flags |= UNP_GCMARK;
  
  			so = unp->unp_socket;
  			unp_scan(so->so_rcv.sb_mb, unp_mark);
  		}
  	} while (unp_defer);
  
  	/*
  	 * If there are any unreferenced sockets, then for each dispose
  	 * of files in its receive buffer and then close it.
  	 */
  	if (nunref) {
  		LIST_FOREACH(unp, &unp_head, unp_link) {
  			if (unp->unp_flags & UNP_GCDEAD)
  				unp_scan(unp->unp_socket->so_rcv.sb_mb,
  				    unp_discard);
  		}
  	}
  	unp_gcing = 0;
  }
  
  void
  unp_dispose(struct mbuf *m)
  {
  
  	if (m)
  		unp_scan(m, unp_discard);
  }
  
  void
  unp_scan(struct mbuf *m0, void (*op)(struct fdpass *, int))
  {
  	struct mbuf *m;
  	struct fdpass *rp;
  	struct cmsghdr *cm;
  	int qfds;
  
  	while (m0) {
  		for (m = m0; m; m = m->m_next) {
  			if (m->m_type == MT_CONTROL &&
  			    m->m_len >= sizeof(*cm)) {
  				cm = mtod(m, struct cmsghdr *);
  				if (cm->cmsg_level != SOL_SOCKET ||
  				    cm->cmsg_type != SCM_RIGHTS)
  					continue;
  				qfds = (cm->cmsg_len - CMSG_ALIGN(sizeof *cm))
  				    / sizeof(struct fdpass);
  				if (qfds > 0) {
  					rp = (struct fdpass *)CMSG_DATA(cm);
  					op(rp, qfds);
  				}
  				break;		/* XXX, but saves time */
  			}
  		}
  		m0 = m0->m_nextpkt;
  	}
  }
  
  void
  unp_mark(struct fdpass *rp, int nfds)
  {
  	struct unpcb *unp;
  	int i;
  
  	for (i = 0; i < nfds; i++) {
  		if (rp[i].fp == NULL)
  			continue;
  
  		unp = fptounp(rp[i].fp);
  		if (unp == NULL)
  			continue;
  
  		if (unp->unp_flags & (UNP_GCMARK|UNP_GCDEFER))
  			continue;
  
  		unp_defer++;
  		unp->unp_flags |= UNP_GCDEFER;
  		unp->unp_flags &= ~UNP_GCDEAD;
  	}
  }
  
  void
  unp_discard(struct fdpass *rp, int nfds)
  {
  	struct unp_deferral *defer;
  
  	/* copy the file pointers to a deferral structure */
  	defer = malloc(sizeof(*defer) + sizeof(*rp) * nfds, M_TEMP, M_WAITOK);
  	defer->ud_n = nfds;
  	memcpy(&defer->ud_fp[0], rp, sizeof(*rp) * nfds);
  	memset(rp, 0, sizeof(*rp) * nfds);
  	SLIST_INSERT_HEAD(&unp_deferred, defer, ud_link);
  
  	task_add(systq, &unp_gc_task);
  }
  
  int
  unp_nam2sun(struct mbuf *nam, struct sockaddr_un **sun, size_t *pathlen)
  {
  	struct sockaddr *sa = mtod(nam, struct sockaddr *);
  	size_t size, len;
  
  	if (nam->m_len < offsetof(struct sockaddr, sa_data))
  		return EINVAL;
  	if (sa->sa_family != AF_UNIX)
  		return EAFNOSUPPORT;
  	if (sa->sa_len != nam->m_len)
  		return EINVAL;
  	if (sa->sa_len > sizeof(struct sockaddr_un))
  		return EINVAL;
  	*sun = (struct sockaddr_un *)sa;
  
  	/* ensure that sun_path is NUL terminated and fits */
  	size = (*sun)->sun_len - offsetof(struct sockaddr_un, sun_path);
  	len = strnlen((*sun)->sun_path, size);
  	if (len == sizeof((*sun)->sun_path))
  		return EINVAL;
  	if (len == size) {
  		if (m_trailingspace(nam) == 0)
  			return EINVAL;
  		nam->m_len++;
  		(*sun)->sun_len++;
  		(*sun)->sun_path[len] = '\0';
  	}
  	if (pathlen != NULL)
  		*pathlen = len;
  
  	return 0;
  }