FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_usrreq.c

     /*-
      * Copyright (c) 1982, 1986, 1989, 1991, 1993
      *      The Regents of the University of California.
      * Copyright (c) 2004-2009 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
     */
    
    /*
     * UNIX Domain (Local) Sockets
     *
     * This is an implementation of UNIX (local) domain sockets.  Each socket has
     * an associated struct unpcb (UNIX protocol control block).  Stream sockets
     * may be connected to 0 or 1 other socket.  Datagram sockets may be
     * connected to 0, 1, or many other sockets.  Sockets may be created and
     * connected in pairs (socketpair(2)), or bound/connected to using the file
     * system name space.  For most purposes, only the receive socket buffer is
     * used, as sending on one socket delivers directly to the receive socket
     * buffer of a second socket.
     *
     * The implementation is substantially complicated by the fact that
     * "ancillary data", such as file descriptors or credentials, may be passed
     * across UNIX domain sockets.  The potential for passing UNIX domain sockets
     * over other UNIX domain sockets requires the implementation of a simple
     * garbage collector to find and tear down cycles of disconnected sockets.
     *
     * TODO:
     *      RDM
     *      rethink name space problems
     *      need a proper out-of-band
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_ddb.h"
    
    #include <sys/param.h>
    #include <sys/capsicum.h>
    #include <sys/domain.h>
    #include <sys/fcntl.h>
    #include <sys/malloc.h>         /* XXX must be before <sys/file.h> */
    #include <sys/eventhandler.h>
    #include <sys/file.h>
    #include <sys/filedesc.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mbuf.h>
    #include <sys/mount.h>
    #include <sys/mutex.h>
    #include <sys/namei.h>
    #include <sys/proc.h>
    #include <sys/protosw.h>
    #include <sys/queue.h>
    #include <sys/resourcevar.h>
    #include <sys/rwlock.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 <net/vnet.h>
    
    #ifdef DDB
    #include <ddb/ddb.h>
    #endif
    
   #include <security/mac/mac_framework.h>
   
   #include <vm/uma.h>
   
   MALLOC_DECLARE(M_FILECAPS);
   
   /*
    * Locking key:
    * (l)  Locked using list lock
    * (g)  Locked using linkage lock
    */
   
   static uma_zone_t       unp_zone;
   static unp_gen_t        unp_gencnt;     /* (l) */
   static u_int            unp_count;      /* (l) Count of local sockets. */
   static ino_t            unp_ino;        /* Prototype for fake inode numbers. */
   static int              unp_rights;     /* (g) File descriptors in flight. */
   static struct unp_head  unp_shead;      /* (l) List of stream sockets. */
   static struct unp_head  unp_dhead;      /* (l) List of datagram sockets. */
   static struct unp_head  unp_sphead;     /* (l) List of seqpacket sockets. */
   
   struct unp_defer {
           SLIST_ENTRY(unp_defer) ud_link;
           struct file *ud_fp;
   };
   static SLIST_HEAD(, unp_defer) unp_defers;
   static int unp_defers_count;
   
   static const struct sockaddr    sun_noname = { sizeof(sun_noname), AF_LOCAL };
   
   /*
    * 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 timeout_task unp_gc_task;
   
   /*
    * The close of unix domain sockets attached as SCM_RIGHTS is
    * postponed to the taskqueue, to avoid arbitrary recursion depth.
    * The attached sockets might have another sockets attached.
    */
   static struct task      unp_defer_task;
   
   /*
    * 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 u_long   unpsp_sendspace = PIPSIZ;       /* really max datagram size */
   static u_long   unpsp_recvspace = PIPSIZ;
   
   static SYSCTL_NODE(_net, PF_LOCAL, local, CTLFLAG_RW, 0, "Local domain");
   static SYSCTL_NODE(_net_local, SOCK_STREAM, stream, CTLFLAG_RW, 0,
       "SOCK_STREAM");
   static SYSCTL_NODE(_net_local, SOCK_DGRAM, dgram, CTLFLAG_RW, 0, "SOCK_DGRAM");
   static SYSCTL_NODE(_net_local, SOCK_SEQPACKET, seqpacket, CTLFLAG_RW, 0,
       "SOCK_SEQPACKET");
   
   SYSCTL_ULONG(_net_local_stream, OID_AUTO, sendspace, CTLFLAG_RW,
              &unpst_sendspace, 0, "Default stream send space.");
   SYSCTL_ULONG(_net_local_stream, OID_AUTO, recvspace, CTLFLAG_RW,
              &unpst_recvspace, 0, "Default stream receive space.");
   SYSCTL_ULONG(_net_local_dgram, OID_AUTO, maxdgram, CTLFLAG_RW,
              &unpdg_sendspace, 0, "Default datagram send space.");
   SYSCTL_ULONG(_net_local_dgram, OID_AUTO, recvspace, CTLFLAG_RW,
              &unpdg_recvspace, 0, "Default datagram receive space.");
   SYSCTL_ULONG(_net_local_seqpacket, OID_AUTO, maxseqpacket, CTLFLAG_RW,
              &unpsp_sendspace, 0, "Default seqpacket send space.");
   SYSCTL_ULONG(_net_local_seqpacket, OID_AUTO, recvspace, CTLFLAG_RW,
              &unpsp_recvspace, 0, "Default seqpacket receive space.");
   SYSCTL_INT(_net_local, OID_AUTO, inflight, CTLFLAG_RD, &unp_rights, 0,
       "File descriptors in flight.");
   SYSCTL_INT(_net_local, OID_AUTO, deferred, CTLFLAG_RD,
       &unp_defers_count, 0,
       "File descriptors deferred to taskqueue for close.");
   
   /*
    * Locking and synchronization:
    *
    * Three types of locks exit in the local domain socket implementation: a
    * global list mutex, a global linkage rwlock, and per-unpcb mutexes.  Of the
    * global locks, the list lock protects the socket count, global generation
    * number, and stream/datagram global lists.  The linkage lock protects the
    * interconnection of unpcbs, the v_socket and unp_vnode pointers, and can be
    * held exclusively over the acquisition of multiple unpcb locks to prevent
    * deadlock.
    *
    * UNIX domain sockets each have an unpcb hung off of their so_pcb pointer,
    * allocated in pru_attach() and freed in pru_detach().  The validity of that
    * pointer is an invariant, so no lock is required to dereference the so_pcb
    * pointer if a valid socket reference is held by the caller.  In practice,
    * this is always true during operations performed on a socket.  Each unpcb
    * has a back-pointer to its socket, unp_socket, which will be stable under
    * the same circumstances.
    *
    * This pointer may only be safely dereferenced as long as a valid reference
    * to the unpcb is held.  Typically, this reference will be from the socket,
    * or from another unpcb when the referring unpcb's lock is held (in order
    * that the reference not be invalidated during use).  For example, to follow
    * unp->unp_conn->unp_socket, you need unlock the lock on unp, not unp_conn,
    * as unp_socket remains valid as long as the reference to unp_conn is valid.
    *
    * Fields of unpcbss are locked using a per-unpcb lock, unp_mtx.  Individual
    * atomic reads without the lock may be performed "lockless", but more
    * complex reads and read-modify-writes require the mutex to be held.  No
    * lock order is defined between unpcb locks -- multiple unpcb locks may be
    * acquired at the same time only when holding the linkage rwlock
    * exclusively, which prevents deadlocks.
    *
    * Blocking with UNIX domain sockets is a tricky issue: unlike most network
    * protocols, bind() is a non-atomic operation, and connect() requires
    * potential sleeping in the protocol, due to potentially waiting on local or
    * distributed file systems.  We try to separate "lookup" operations, which
    * may sleep, and the IPC operations themselves, which typically can occur
    * with relative atomicity as locks can be held over the entire operation.
    *
    * Another tricky issue is simultaneous multi-threaded or multi-process
    * access to a single UNIX domain socket.  These are handled by the flags
    * UNP_CONNECTING and UNP_BINDING, which prevent concurrent connecting or
    * binding, both of which involve dropping UNIX domain socket locks in order
    * to perform namei() and other file system operations.
    */
   static struct rwlock    unp_link_rwlock;
   static struct mtx       unp_list_lock;
   static struct mtx       unp_defers_lock;
   
   #define UNP_LINK_LOCK_INIT()            rw_init(&unp_link_rwlock,       \
                                               "unp_link_rwlock")
   
   #define UNP_LINK_LOCK_ASSERT()  rw_assert(&unp_link_rwlock,     \
                                               RA_LOCKED)
   #define UNP_LINK_UNLOCK_ASSERT()        rw_assert(&unp_link_rwlock,     \
                                               RA_UNLOCKED)
   
   #define UNP_LINK_RLOCK()                rw_rlock(&unp_link_rwlock)
   #define UNP_LINK_RUNLOCK()              rw_runlock(&unp_link_rwlock)
   #define UNP_LINK_WLOCK()                rw_wlock(&unp_link_rwlock)
   #define UNP_LINK_WUNLOCK()              rw_wunlock(&unp_link_rwlock)
   #define UNP_LINK_WLOCK_ASSERT()         rw_assert(&unp_link_rwlock,     \
                                               RA_WLOCKED)
   
   #define UNP_LIST_LOCK_INIT()            mtx_init(&unp_list_lock,        \
                                               "unp_list_lock", NULL, MTX_DEF)
   #define UNP_LIST_LOCK()                 mtx_lock(&unp_list_lock)
   #define UNP_LIST_UNLOCK()               mtx_unlock(&unp_list_lock)
   
   #define UNP_DEFERRED_LOCK_INIT()        mtx_init(&unp_defers_lock, \
                                               "unp_defer", NULL, MTX_DEF)
   #define UNP_DEFERRED_LOCK()             mtx_lock(&unp_defers_lock)
   #define UNP_DEFERRED_UNLOCK()           mtx_unlock(&unp_defers_lock)
   
   #define UNP_PCB_LOCK_INIT(unp)          mtx_init(&(unp)->unp_mtx,       \
                                               "unp_mtx", "unp_mtx",       \
                                               MTX_DUPOK|MTX_DEF|MTX_RECURSE)
   #define UNP_PCB_LOCK_DESTROY(unp)       mtx_destroy(&(unp)->unp_mtx)
   #define UNP_PCB_LOCK(unp)               mtx_lock(&(unp)->unp_mtx)
   #define UNP_PCB_UNLOCK(unp)             mtx_unlock(&(unp)->unp_mtx)
   #define UNP_PCB_LOCK_ASSERT(unp)        mtx_assert(&(unp)->unp_mtx, MA_OWNED)
   
   static int      uipc_connect2(struct socket *, struct socket *);
   static int      uipc_ctloutput(struct socket *, struct sockopt *);
   static int      unp_connect(struct socket *, struct sockaddr *,
                       struct thread *);
   static int      unp_connectat(int, struct socket *, struct sockaddr *,
                       struct thread *);
   static int      unp_connect2(struct socket *so, struct socket *so2, int);
   static void     unp_disconnect(struct unpcb *unp, struct unpcb *unp2);
   static void     unp_dispose(struct mbuf *);
   static void     unp_dispose_so(struct socket *so);
   static void     unp_shutdown(struct unpcb *);
   static void     unp_drop(struct unpcb *);
   static void     unp_gc(__unused void *, int);
   static void     unp_scan(struct mbuf *, void (*)(struct filedescent **, int));
   static void     unp_discard(struct file *);
   static void     unp_freerights(struct filedescent **, int);
   static void     unp_init(void);
   static int      unp_internalize(struct mbuf **, struct thread *);
   static void     unp_internalize_fp(struct file *);
   static int      unp_externalize(struct mbuf *, struct mbuf **, int);
   static int      unp_externalize_fp(struct file *);
   static struct mbuf      *unp_addsockcred(struct thread *, struct mbuf *);
   static void     unp_process_defers(void * __unused, int);
   
   /*
    * Definitions of protocols supported in the LOCAL domain.
    */
   static struct domain localdomain;
   static struct pr_usrreqs uipc_usrreqs_dgram, uipc_usrreqs_stream;
   static struct pr_usrreqs uipc_usrreqs_seqpacket;
   static struct protosw localsw[] = {
   {
           .pr_type =              SOCK_STREAM,
           .pr_domain =            &localdomain,
           .pr_flags =             PR_CONNREQUIRED|PR_WANTRCVD|PR_RIGHTS,
           .pr_ctloutput =         &uipc_ctloutput,
           .pr_usrreqs =           &uipc_usrreqs_stream
   },
   {
           .pr_type =              SOCK_DGRAM,
           .pr_domain =            &localdomain,
           .pr_flags =             PR_ATOMIC|PR_ADDR|PR_RIGHTS,
           .pr_ctloutput =         &uipc_ctloutput,
           .pr_usrreqs =           &uipc_usrreqs_dgram
   },
   {
           .pr_type =              SOCK_SEQPACKET,
           .pr_domain =            &localdomain,
   
           /*
            * XXXRW: For now, PR_ADDR because soreceive will bump into them
            * due to our use of sbappendaddr.  A new sbappend variants is needed
            * that supports both atomic record writes and control data.
            */
           .pr_flags =             PR_ADDR|PR_ATOMIC|PR_CONNREQUIRED|PR_WANTRCVD|
                                       PR_RIGHTS,
           .pr_ctloutput =         &uipc_ctloutput,
           .pr_usrreqs =           &uipc_usrreqs_seqpacket,
   },
   };
   
   static struct domain localdomain = {
           .dom_family =           AF_LOCAL,
           .dom_name =             "local",
           .dom_init =             unp_init,
           .dom_externalize =      unp_externalize,
           .dom_dispose =          unp_dispose_so,
           .dom_protosw =          localsw,
           .dom_protoswNPROTOSW =  &localsw[nitems(localsw)]
   };
   DOMAIN_SET(local);
   
   static void
   uipc_abort(struct socket *so)
   {
           struct unpcb *unp, *unp2;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_abort: unp == NULL"));
   
           UNP_LINK_WLOCK();
           UNP_PCB_LOCK(unp);
           unp2 = unp->unp_conn;
           if (unp2 != NULL) {
                   UNP_PCB_LOCK(unp2);
                   unp_drop(unp2);
                   UNP_PCB_UNLOCK(unp2);
           }
           UNP_PCB_UNLOCK(unp);
           UNP_LINK_WUNLOCK();
   }
   
   static int
   uipc_accept(struct socket *so, struct sockaddr **nam)
   {
           struct unpcb *unp, *unp2;
           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!).
            */
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_accept: unp == NULL"));
   
           *nam = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
           UNP_LINK_RLOCK();
           unp2 = unp->unp_conn;
           if (unp2 != NULL && unp2->unp_addr != NULL) {
                   UNP_PCB_LOCK(unp2);
                   sa = (struct sockaddr *) unp2->unp_addr;
                   bcopy(sa, *nam, sa->sa_len);
                   UNP_PCB_UNLOCK(unp2);
           } else {
                   sa = &sun_noname;
                   bcopy(sa, *nam, sa->sa_len);
           }
           UNP_LINK_RUNLOCK();
           return (0);
   }
   
   static int
   uipc_attach(struct socket *so, int proto, struct thread *td)
   {
           u_long sendspace, recvspace;
           struct unpcb *unp;
           int error;
   
           KASSERT(so->so_pcb == NULL, ("uipc_attach: so_pcb != NULL"));
           if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
                   switch (so->so_type) {
                   case SOCK_STREAM:
                           sendspace = unpst_sendspace;
                           recvspace = unpst_recvspace;
                           break;
   
                   case SOCK_DGRAM:
                           sendspace = unpdg_sendspace;
                           recvspace = unpdg_recvspace;
                           break;
   
                   case SOCK_SEQPACKET:
                           sendspace = unpsp_sendspace;
                           recvspace = unpsp_recvspace;
                           break;
   
                   default:
                           panic("uipc_attach");
                   }
                   error = soreserve(so, sendspace, recvspace);
                   if (error)
                           return (error);
           }
           unp = uma_zalloc(unp_zone, M_NOWAIT | M_ZERO);
           if (unp == NULL)
                   return (ENOBUFS);
           LIST_INIT(&unp->unp_refs);
           UNP_PCB_LOCK_INIT(unp);
           unp->unp_socket = so;
           so->so_pcb = unp;
           unp->unp_refcount = 1;
           if (so->so_head != NULL)
                   unp->unp_flags |= UNP_NASCENT;
   
           UNP_LIST_LOCK();
           unp->unp_gencnt = ++unp_gencnt;
           unp_count++;
           switch (so->so_type) {
           case SOCK_STREAM:
                   LIST_INSERT_HEAD(&unp_shead, unp, unp_link);
                   break;
   
           case SOCK_DGRAM:
                   LIST_INSERT_HEAD(&unp_dhead, unp, unp_link);
                   break;
   
           case SOCK_SEQPACKET:
                   LIST_INSERT_HEAD(&unp_sphead, unp, unp_link);
                   break;
   
           default:
                   panic("uipc_attach");
           }
           UNP_LIST_UNLOCK();
   
           return (0);
   }
   
   static int
   uipc_bindat(int fd, struct socket *so, struct sockaddr *nam, struct thread *td)
   {
           struct sockaddr_un *soun = (struct sockaddr_un *)nam;
           struct vattr vattr;
           int error, namelen;
           struct nameidata nd;
           struct unpcb *unp;
           struct vnode *vp;
           struct mount *mp;
           cap_rights_t rights;
           char *buf;
   
           if (nam->sa_family != AF_UNIX)
                   return (EAFNOSUPPORT);
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_bind: unp == NULL"));
   
           if (soun->sun_len > sizeof(struct sockaddr_un))
                   return (EINVAL);
           namelen = soun->sun_len - offsetof(struct sockaddr_un, sun_path);
           if (namelen <= 0)
                   return (EINVAL);
   
           /*
            * We don't allow simultaneous bind() calls on a single UNIX domain
            * socket, so flag in-progress operations, and return an error if an
            * operation is already in progress.
            *
            * Historically, we have not allowed a socket to be rebound, so this
            * also returns an error.  Not allowing re-binding simplifies the
            * implementation and avoids a great many possible failure modes.
            */
           UNP_PCB_LOCK(unp);
           if (unp->unp_vnode != NULL) {
                   UNP_PCB_UNLOCK(unp);
                   return (EINVAL);
           }
           if (unp->unp_flags & UNP_BINDING) {
                   UNP_PCB_UNLOCK(unp);
                   return (EALREADY);
           }
           unp->unp_flags |= UNP_BINDING;
           UNP_PCB_UNLOCK(unp);
   
           buf = malloc(namelen + 1, M_TEMP, M_WAITOK);
           bcopy(soun->sun_path, buf, namelen);
           buf[namelen] = 0;
   
   restart:
           NDINIT_ATRIGHTS(&nd, CREATE, NOFOLLOW | LOCKPARENT | SAVENAME | NOCACHE,
               UIO_SYSSPACE, buf, fd, cap_rights_init(&rights, CAP_BINDAT), td);
   /* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */
           error = namei(&nd);
           if (error)
                   goto error;
           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 error;
                   }
                   error = vn_start_write(NULL, &mp, V_XSLEEP | PCATCH);
                   if (error)
                           goto error;
                   goto restart;
           }
           VATTR_NULL(&vattr);
           vattr.va_type = VSOCK;
           vattr.va_mode = (ACCESSPERMS & ~td->td_proc->p_fd->fd_cmask);
   #ifdef MAC
           error = mac_vnode_check_create(td->td_ucred, nd.ni_dvp, &nd.ni_cnd,
               &vattr);
   #endif
           if (error == 0)
                   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 error;
           }
           vp = nd.ni_vp;
           ASSERT_VOP_ELOCKED(vp, "uipc_bind");
           soun = (struct sockaddr_un *)sodupsockaddr(nam, M_WAITOK);
   
           UNP_LINK_WLOCK();
           UNP_PCB_LOCK(unp);
           VOP_UNP_BIND(vp, unp->unp_socket);
           unp->unp_vnode = vp;
           unp->unp_addr = soun;
           unp->unp_flags &= ~UNP_BINDING;
           UNP_PCB_UNLOCK(unp);
           UNP_LINK_WUNLOCK();
           VOP_UNLOCK(vp, 0);
           vn_finished_write(mp);
           free(buf, M_TEMP);
           return (0);
   
   error:
           UNP_PCB_LOCK(unp);
           unp->unp_flags &= ~UNP_BINDING;
           UNP_PCB_UNLOCK(unp);
           free(buf, M_TEMP);
           return (error);
   }
   
   static int
   uipc_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
   {
   
           return (uipc_bindat(AT_FDCWD, so, nam, td));
   }
   
   static int
   uipc_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
   {
           int error;
   
           KASSERT(td == curthread, ("uipc_connect: td != curthread"));
           UNP_LINK_WLOCK();
           error = unp_connect(so, nam, td);
           UNP_LINK_WUNLOCK();
           return (error);
   }
   
   static int
   uipc_connectat(int fd, struct socket *so, struct sockaddr *nam,
       struct thread *td)
   {
           int error;
   
           KASSERT(td == curthread, ("uipc_connectat: td != curthread"));
           UNP_LINK_WLOCK();
           error = unp_connectat(fd, so, nam, td);
           UNP_LINK_WUNLOCK();
           return (error);
   }
   
   static void
   uipc_close(struct socket *so)
   {
           struct unpcb *unp, *unp2;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_close: unp == NULL"));
   
           UNP_LINK_WLOCK();
           UNP_PCB_LOCK(unp);
           unp2 = unp->unp_conn;
           if (unp2 != NULL) {
                   UNP_PCB_LOCK(unp2);
                   unp_disconnect(unp, unp2);
                   UNP_PCB_UNLOCK(unp2);
           }
           UNP_PCB_UNLOCK(unp);
           UNP_LINK_WUNLOCK();
   }
   
   static int
   uipc_connect2(struct socket *so1, struct socket *so2)
   {
           struct unpcb *unp, *unp2;
           int error;
   
           UNP_LINK_WLOCK();
           unp = so1->so_pcb;
           KASSERT(unp != NULL, ("uipc_connect2: unp == NULL"));
           UNP_PCB_LOCK(unp);
           unp2 = so2->so_pcb;
           KASSERT(unp2 != NULL, ("uipc_connect2: unp2 == NULL"));
           UNP_PCB_LOCK(unp2);
           error = unp_connect2(so1, so2, PRU_CONNECT2);
           UNP_PCB_UNLOCK(unp2);
           UNP_PCB_UNLOCK(unp);
           UNP_LINK_WUNLOCK();
           return (error);
   }
   
   static void
   uipc_detach(struct socket *so)
   {
           struct unpcb *unp, *unp2;
           struct sockaddr_un *saved_unp_addr;
           struct vnode *vp;
           int freeunp, local_unp_rights;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_detach: unp == NULL"));
   
           vp = NULL;
           local_unp_rights = 0;
   
           UNP_LIST_LOCK();
           LIST_REMOVE(unp, unp_link);
           unp->unp_gencnt = ++unp_gencnt;
           --unp_count;
           UNP_LIST_UNLOCK();
   
           if ((unp->unp_flags & UNP_NASCENT) != 0) {
                   UNP_PCB_LOCK(unp);
                   goto teardown;
           }
           UNP_LINK_WLOCK();
           UNP_PCB_LOCK(unp);
   
           /*
            * XXXRW: Should assert vp->v_socket == so.
            */
           if ((vp = unp->unp_vnode) != NULL) {
                   VOP_UNP_DETACH(vp);
                   unp->unp_vnode = NULL;
           }
           unp2 = unp->unp_conn;
           if (unp2 != NULL) {
                   UNP_PCB_LOCK(unp2);
                   unp_disconnect(unp, unp2);
                   UNP_PCB_UNLOCK(unp2);
           }
   
           /*
            * We hold the linkage lock exclusively, so it's OK to acquire
            * multiple pcb locks at a time.
            */
           while (!LIST_EMPTY(&unp->unp_refs)) {
                   struct unpcb *ref = LIST_FIRST(&unp->unp_refs);
   
                   UNP_PCB_LOCK(ref);
                   unp_drop(ref);
                   UNP_PCB_UNLOCK(ref);
           }
           local_unp_rights = unp_rights;
           UNP_LINK_WUNLOCK();
   teardown:
           unp->unp_socket->so_pcb = NULL;
           saved_unp_addr = unp->unp_addr;
           unp->unp_addr = NULL;
           unp->unp_refcount--;
           freeunp = (unp->unp_refcount == 0);
           if (saved_unp_addr != NULL)
                   free(saved_unp_addr, M_SONAME);
           if (freeunp) {
                   UNP_PCB_LOCK_DESTROY(unp);
                   uma_zfree(unp_zone, unp);
           } else
                   UNP_PCB_UNLOCK(unp);
           if (vp)
                   vrele(vp);
           if (local_unp_rights)
                   taskqueue_enqueue_timeout(taskqueue_thread, &unp_gc_task, -1);
   }
   
   static int
   uipc_disconnect(struct socket *so)
   {
           struct unpcb *unp, *unp2;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_disconnect: unp == NULL"));
   
           UNP_LINK_WLOCK();
           UNP_PCB_LOCK(unp);
           unp2 = unp->unp_conn;
           if (unp2 != NULL) {
                   UNP_PCB_LOCK(unp2);
                   unp_disconnect(unp, unp2);
                   UNP_PCB_UNLOCK(unp2);
           }
           UNP_PCB_UNLOCK(unp);
           UNP_LINK_WUNLOCK();
           return (0);
   }
   
   static int
   uipc_listen(struct socket *so, int backlog, struct thread *td)
   {
           struct unpcb *unp;
           int error;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_listen: unp == NULL"));
   
           UNP_PCB_LOCK(unp);
           if (unp->unp_vnode == NULL) {
                   /* Already connected or not bound to an address. */
                   error = unp->unp_conn != NULL ? EINVAL : EDESTADDRREQ;
                   UNP_PCB_UNLOCK(unp);
                   return (error);
           }
   
           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);
           UNP_PCB_UNLOCK(unp);
           return (error);
   }
   
   static int
   uipc_peeraddr(struct socket *so, struct sockaddr **nam)
   {
           struct unpcb *unp, *unp2;
           const struct sockaddr *sa;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("uipc_peeraddr: unp == NULL"));
   
           *nam = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
           UNP_LINK_RLOCK();
           /*
            * 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.
            */
           unp2 = unp->unp_conn;
           if (unp2 != NULL) {
                   UNP_PCB_LOCK(unp2);
                   if (unp2->unp_addr != NULL)
                           sa = (struct sockaddr *) unp2->unp_addr;
                   else
                           sa = &sun_noname;
                   bcopy(sa, *nam, sa->sa_len);
                   UNP_PCB_UNLOCK(unp2);
           } else {
                   sa = &sun_noname;
                   bcopy(sa, *nam, sa->sa_len);
           }
           UNP_LINK_RUNLOCK();
           return (0);
   }
   
   static int
   uipc_rcvd(struct socket *so, int flags)
   {
           struct unpcb *unp, *unp2;
           struct socket *so2;
           u_int mbcnt, sbcc;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("%s: unp == NULL", __func__));
           KASSERT(so->so_type == SOCK_STREAM || so->so_type == SOCK_SEQPACKET,
               ("%s: socktype %d", __func__, so->so_type));
   
           /*
            * Adjust backpressure on sender and wakeup any waiting to write.
            *
            * The unp lock is acquired to maintain the validity of the unp_conn
            * pointer; no lock on unp2 is required as unp2->unp_socket will be
            * static as long as we don't permit unp2 to disconnect from unp,
            * which is prevented by the lock on unp.  We cache values from
            * so_rcv to avoid holding the so_rcv lock over the entire
            * transaction on the remote so_snd.
            */
           SOCKBUF_LOCK(&so->so_rcv);
           mbcnt = so->so_rcv.sb_mbcnt;
           sbcc = sbavail(&so->so_rcv);
           SOCKBUF_UNLOCK(&so->so_rcv);
           /*
            * There is a benign race condition at this point.  If we're planning to
            * clear SB_STOP, but uipc_send is called on the connected socket at
            * this instant, it might add data to the sockbuf and set SB_STOP.  Then
            * we would erroneously clear SB_STOP below, even though the sockbuf is
            * full.  The race is benign because the only ill effect is to allow the
            * sockbuf to exceed its size limit, and the size limits are not
            * strictly guaranteed anyway.
            */
           UNP_PCB_LOCK(unp);
           unp2 = unp->unp_conn;
           if (unp2 == NULL) {
                   UNP_PCB_UNLOCK(unp);
                   return (0);
           }
           so2 = unp2->unp_socket;
           SOCKBUF_LOCK(&so2->so_snd);
           if (sbcc < so2->so_snd.sb_hiwat && mbcnt < so2->so_snd.sb_mbmax)
                   so2->so_snd.sb_flags &= ~SB_STOP;
           sowwakeup_locked(so2);
           UNP_PCB_UNLOCK(unp);
           return (0);
   }
   
   static int
   uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
       struct mbuf *control, struct thread *td)
   {
           struct unpcb *unp, *unp2;
           struct socket *so2;
           u_int mbcnt, sbcc;
           int error = 0;
   
           unp = sotounpcb(so);
           KASSERT(unp != NULL, ("%s: unp == NULL", __func__));
           KASSERT(so->so_type == SOCK_STREAM || so->so_type == SOCK_DGRAM ||
               so->so_type == SOCK_SEQPACKET,
               ("%s: socktype %d", __func__, so->so_type));
   
           if (flags & PRUS_OOB) {
                   error = EOPNOTSUPP;
                   goto release;
           }
           if (control != NULL && (error = unp_internalize(&control, td)))
                   goto release;
           if ((nam != NULL) || (flags & PRUS_EOF))
                   UNP_LINK_WLOCK();
           else
                   UNP_LINK_RLOCK();
           switch (so->so_type) {
           case SOCK_DGRAM:
           {
                   const struct sockaddr *from;
   
                   unp2 = unp->unp_conn;
                   if (nam != NULL) {
                           UNP_LINK_WLOCK_ASSERT();
                           if (unp2 != NULL) {
                                   error = EISCONN;
                                   break;
                           }
                           error = unp_connect(so, nam, td);
                           if (error)
                                   break;
                           unp2 = unp->unp_conn;
                   }
   
                   /*
                    * Because connect() and send() are non-atomic in a sendto()
                    * with a target address, it's possible that the socket will
                    * have disconnected before the send() can run.  In that case
                    * return the slightly counter-intuitive but otherwise
                    * correct error that the socket is not connected.
                    */
                   if (unp2 == NULL) {
                           error = ENOTCONN;
                           break;
                   }
                   /* Lockless read. */
                   if (unp2->unp_flags & UNP_WANTCRED)
                           control = unp_addsockcred(td, control);
                   UNP_PCB_LOCK(unp);
                   if (unp->unp_addr != NULL)
                           from = (struct sockaddr *)unp->unp_addr;
                   else
                           from = &sun_noname;
                   so2 = unp2->unp_socket;
                   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_LINK_WLOCK_ASSERT();
                           UNP_PCB_LOCK(unp2);
                           unp_disconnect(unp, unp2);
                           UNP_PCB_UNLOCK(unp2);
                   }
                   UNP_PCB_UNLOCK(unp);
                   break;
           }
   
           case SOCK_SEQPACKET:
           case SOCK_STREAM:
                   if ((so->so_state & SS_ISCONNECTED) == 0) {
                           if (nam != NULL) {
                                   UNP_LINK_WLOCK_ASSERT();
                                   error = unp_connect(so, nam, td);
                                   if (error)
                                           break;  /* XXX */
                           } else {
                                   error = ENOTCONN;
                                   break;
                           }
                   }
   
                   /* Lockless read. */
                   if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                           error = EPIPE;
                           break;
                   }
   
                   /*
                    * Because connect() and send() are non-atomic in a sendto()
                    * with a target address, it's possible that the socket will
                    * have disconnected before the send() can run.  In that case
                    * return the slightly counter-intuitive but otherwise
                    * correct error that the socket is not connected.
                    *
                    * Locking here must be done carefully: the linkage lock
                    * prevents interconnections between unpcbs from changing, so
                    * we can traverse from unp to unp2 without acquiring unp's
                    * lock.  Socket buffer locks follow unpcb locks, so we can
                    * acquire both remote and lock socket buffer locks.
                    */
                   unp2 = unp->unp_conn;
                   if (unp2 == NULL) {
                           error = ENOTCONN;
                           break;
                   }
                   so2 = unp2->unp_socket;
                   UNP_PCB_LOCK(unp2);
                   SOCKBUF_LOCK(&so2->so_rcv);
                   if (unp2->unp_flags & UNP_WANTCRED) {
                           /*
                            * Credentials are passed only once on SOCK_STREAM
                            * and SOCK_SEQPACKET.
                            */
                           unp2->unp_flags &= ~UNP_WANTCRED;
                           control = unp_addsockcred(td, control);
                   }
   
                   /*
                    * Send to paired receive port and wake up readers.  Don't
                    * check for space available in the receive buffer if we're
                    * attaching ancillary data; Unix domain sockets only check
                    * for space in the sending sockbuf, and that check is
                    * performed one level up the stack.  At that level we cannot
                    * precisely account for the amount of buffer space used
                    * (e.g., because control messages are not yet internalized).
                    */
                   switch (so->so_type) {
                   case SOCK_STREAM:
                           if (control != NULL) {
                                   sbappendcontrol_locked(&so2->so_rcv, m,
                                       control);
                                   control = NULL;
                          } else
                                  sbappend_locked(&so2->so_rcv, m, flags);
                          break;
  
                  case SOCK_SEQPACKET: {
                          const struct sockaddr *from;
  
                          from = &sun_noname;
                          if (sbappendaddr_nospacecheck_locked(&so2->so_rcv,
                              from, m, control))
                                  control = NULL;
                          break;
                          }
                  }
  
                  mbcnt = so2->so_rcv.sb_mbcnt;
                  sbcc = sbavail(&so2->so_rcv);
                  if (sbcc)
                          sorwakeup_locked(so2);
                  else
                          SOCKBUF_UNLOCK(&so2->so_rcv);
  
                  /*
                   * The PCB lock on unp2 protects the SB_STOP flag.  Without it,
                   * it would be possible for uipc_rcvd to be called at this
                   * point, drain the receiving sockbuf, clear SB_STOP, and then
                   * we would set SB_STOP below.  That could lead to an empty
                   * sockbuf having SB_STOP set
                   */
                  SOCKBUF_LOCK(&so->so_snd);
                  if (sbcc >= so->so_snd.sb_hiwat || mbcnt >= so->so_snd.sb_mbmax)
                          so->so_snd.sb_flags |= SB_STOP;
                  SOCKBUF_UNLOCK(&so->so_snd);
                  UNP_PCB_UNLOCK(unp2);
                  m = NULL;
                  break;
          }
  
          /*
           * PRUS_EOF is equivalent to pru_send followed by pru_shutdown.
           */
          if (flags & PRUS_EOF) {
                  UNP_PCB_LOCK(unp);
                  socantsendmore(so);
                  unp_shutdown(unp);
                  UNP_PCB_UNLOCK(unp);
          }
  
          if ((nam != NULL) || (flags & PRUS_EOF))
                  UNP_LINK_WUNLOCK();
          else
                  UNP_LINK_RUNLOCK();
  
          if (control != NULL && error != 0)
                  unp_dispose(control);
  
  release:
          if (control != NULL)
                  m_freem(control);
          /*
           * In case of PRUS_NOTREADY, uipc_ready() is responsible
           * for freeing memory.
           */   
          if (m != NULL && (flags & PRUS_NOTREADY) == 0)
                  m_freem(m);
          return (error);
  }
  
  static int
  uipc_ready(struct socket *so, struct mbuf *m, int count)
  {
          struct unpcb *unp, *unp2;
          struct socket *so2;
          int error;
  
          unp = sotounpcb(so);
  
          UNP_LINK_RLOCK();
          if ((unp2 = unp->unp_conn) == NULL) {
                  UNP_LINK_RUNLOCK();
                  for (int i = 0; i < count; i++)
                          m = m_free(m);
                  return (ECONNRESET);
          }
          UNP_PCB_LOCK(unp2);
          so2 = unp2->unp_socket;
  
          SOCKBUF_LOCK(&so2->so_rcv);
          if ((error = sbready(&so2->so_rcv, m, count)) == 0)
                  sorwakeup_locked(so2);
          else
                  SOCKBUF_UNLOCK(&so2->so_rcv);
  
          UNP_PCB_UNLOCK(unp2);
          UNP_LINK_RUNLOCK();
  
          return (error);
  }
  
  static int
  uipc_sense(struct socket *so, struct stat *sb)
  {
          struct unpcb *unp;
  
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("uipc_sense: unp == NULL"));
  
          sb->st_blksize = so->so_snd.sb_hiwat;
          UNP_PCB_LOCK(unp);
          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_PCB_UNLOCK(unp);
          return (0);
  }
  
  static int
  uipc_shutdown(struct socket *so)
  {
          struct unpcb *unp;
  
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("uipc_shutdown: unp == NULL"));
  
          UNP_LINK_WLOCK();
          UNP_PCB_LOCK(unp);
          socantsendmore(so);
          unp_shutdown(unp);
          UNP_PCB_UNLOCK(unp);
          UNP_LINK_WUNLOCK();
          return (0);
  }
  
  static int
  uipc_sockaddr(struct socket *so, struct sockaddr **nam)
  {
          struct unpcb *unp;
          const struct sockaddr *sa;
  
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("uipc_sockaddr: unp == NULL"));
  
          *nam = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
          UNP_PCB_LOCK(unp);
          if (unp->unp_addr != NULL)
                  sa = (struct sockaddr *) unp->unp_addr;
          else
                  sa = &sun_noname;
          bcopy(sa, *nam, sa->sa_len);
          UNP_PCB_UNLOCK(unp);
          return (0);
  }
  
  static struct pr_usrreqs uipc_usrreqs_dgram = {
          .pru_abort =            uipc_abort,
          .pru_accept =           uipc_accept,
          .pru_attach =           uipc_attach,
          .pru_bind =             uipc_bind,
          .pru_bindat =           uipc_bindat,
          .pru_connect =          uipc_connect,
          .pru_connectat =        uipc_connectat,
          .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_soreceive =        soreceive_dgram,
          .pru_close =            uipc_close,
  };
  
  static struct pr_usrreqs uipc_usrreqs_seqpacket = {
          .pru_abort =            uipc_abort,
          .pru_accept =           uipc_accept,
          .pru_attach =           uipc_attach,
          .pru_bind =             uipc_bind,
          .pru_bindat =           uipc_bindat,
          .pru_connect =          uipc_connect,
          .pru_connectat =        uipc_connectat,
          .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_soreceive =        soreceive_generic,      /* XXX: or...? */
          .pru_close =            uipc_close,
  };
  
  static struct pr_usrreqs uipc_usrreqs_stream = {
          .pru_abort =            uipc_abort,
          .pru_accept =           uipc_accept,
          .pru_attach =           uipc_attach,
          .pru_bind =             uipc_bind,
          .pru_bindat =           uipc_bindat,
          .pru_connect =          uipc_connect,
          .pru_connectat =        uipc_connectat,
          .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_ready =            uipc_ready,
          .pru_sense =            uipc_sense,
          .pru_shutdown =         uipc_shutdown,
          .pru_sockaddr =         uipc_sockaddr,
          .pru_soreceive =        soreceive_generic,
          .pru_close =            uipc_close,
  };
  
  static 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 = sotounpcb(so);
          KASSERT(unp != NULL, ("uipc_ctloutput: unp == NULL"));
          error = 0;
          switch (sopt->sopt_dir) {
          case SOPT_GET:
                  switch (sopt->sopt_name) {
                  case LOCAL_PEERCRED:
                          UNP_PCB_LOCK(unp);
                          if (unp->unp_flags & UNP_HAVEPC)
                                  xu = unp->unp_peercred;
                          else {
                                  if (so->so_type == SOCK_STREAM)
                                          error = ENOTCONN;
                                  else
                                          error = EINVAL;
                          }
                          UNP_PCB_UNLOCK(unp);
                          if (error == 0)
                                  error = sooptcopyout(sopt, &xu, sizeof(xu));
                          break;
  
                  case LOCAL_CREDS:
                          /* Unlocked read. */
                          optval = unp->unp_flags & UNP_WANTCRED ? 1 : 0;
                          error = sooptcopyout(sopt, &optval, sizeof(optval));
                          break;
  
                  case LOCAL_CONNWAIT:
                          /* Unlocked read. */
                          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) do {                                                \
          UNP_PCB_LOCK(unp);                                              \
          if (optval)                                                     \
                  unp->unp_flags |= bit;                                  \
          else                                                            \
                  unp->unp_flags &= ~bit;                                 \
          UNP_PCB_UNLOCK(unp);                                            \
  } while (0)
  
                          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;
          }
          return (error);
  }
  
  static int
  unp_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
  {
  
          return (unp_connectat(AT_FDCWD, so, nam, td));
  }
  
  static int
  unp_connectat(int fd, 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;
          struct nameidata nd;
          char buf[SOCK_MAXADDRLEN];
          struct sockaddr *sa;
          cap_rights_t rights;
          int error, len;
  
          if (nam->sa_family != AF_UNIX)
                  return (EAFNOSUPPORT);
  
          UNP_LINK_WLOCK_ASSERT();
  
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("unp_connect: unp == NULL"));
  
          if (nam->sa_len > sizeof(struct sockaddr_un))
                  return (EINVAL);
          len = nam->sa_len - offsetof(struct sockaddr_un, sun_path);
          if (len <= 0)
                  return (EINVAL);
          bcopy(soun->sun_path, buf, len);
          buf[len] = 0;
  
          UNP_PCB_LOCK(unp);
          if (unp->unp_flags & UNP_CONNECTING) {
                  UNP_PCB_UNLOCK(unp);
                  return (EALREADY);
          }
          UNP_LINK_WUNLOCK();
          unp->unp_flags |= UNP_CONNECTING;
          UNP_PCB_UNLOCK(unp);
  
          sa = malloc(sizeof(struct sockaddr_un), M_SONAME, M_WAITOK);
          NDINIT_ATRIGHTS(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF,
              UIO_SYSSPACE, buf, fd, cap_rights_init(&rights, CAP_CONNECTAT), 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;
          }
  #ifdef MAC
          error = mac_vnode_check_open(td->td_ucred, vp, VWRITE | VREAD);
          if (error)
                  goto bad;
  #endif
          error = VOP_ACCESS(vp, VWRITE, td->td_ucred, td);
          if (error)
                  goto bad;
  
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("unp_connect: unp == NULL"));
  
          /*
           * Lock linkage lock for two reasons: make sure v_socket is stable,
           * and to protect simultaneous locking of multiple pcbs.
           */
          UNP_LINK_WLOCK();
          VOP_UNP_CONNECT(vp, &so2);
          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) {
                          CURVNET_SET(so2->so_vnet);
                          so3 = sonewconn(so2, 0);
                          CURVNET_RESTORE();
                  } else
                          so3 = NULL;
                  if (so3 == NULL) {
                          error = ECONNREFUSED;
                          goto bad2;
                  }
                  unp = sotounpcb(so);
                  unp2 = sotounpcb(so2);
                  unp3 = sotounpcb(so3);
                  UNP_PCB_LOCK(unp);
                  UNP_PCB_LOCK(unp2);
                  UNP_PCB_LOCK(unp3);
                  if (unp2->unp_addr != NULL) {
                          bcopy(unp2->unp_addr, sa, unp2->unp_addr->sun_len);
                          unp3->unp_addr = (struct sockaddr_un *) sa;
                          sa = NULL;
                  }
  
                  KASSERT(unp2->unp_flags & UNP_HAVEPCCACHED,
                      ("unp_connect: listener without cached peercred"));
                  unp_copy_peercred(td, unp3, unp, unp2);
  
                  UNP_PCB_UNLOCK(unp3);
                  UNP_PCB_UNLOCK(unp2);
                  UNP_PCB_UNLOCK(unp);
  #ifdef MAC
                  mac_socketpeer_set_from_socket(so, so3);
                  mac_socketpeer_set_from_socket(so3, so);
  #endif
  
                  so2 = so3;
          }
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("unp_connect: unp == NULL"));
          unp2 = sotounpcb(so2);
          KASSERT(unp2 != NULL, ("unp_connect: unp2 == NULL"));
          UNP_PCB_LOCK(unp);
          UNP_PCB_LOCK(unp2);
          error = unp_connect2(so, so2, PRU_CONNECT);
          UNP_PCB_UNLOCK(unp2);
          UNP_PCB_UNLOCK(unp);
  bad2:
          UNP_LINK_WUNLOCK();
  bad:
          if (vp != NULL)
                  vput(vp);
          free(sa, M_SONAME);
          UNP_LINK_WLOCK();
          UNP_PCB_LOCK(unp);
          unp->unp_flags &= ~UNP_CONNECTING;
          UNP_PCB_UNLOCK(unp);
          return (error);
  }
  
  /*
   * Set socket peer credentials at connection time.
   *
   * The client's PCB credentials are copied from its process structure.  The
   * server's PCB credentials are copied from the socket on which it called
   * listen(2).  uipc_listen cached that process's credentials at the time.
   */
  void
  unp_copy_peercred(struct thread *td, struct unpcb *client_unp,
      struct unpcb *server_unp, struct unpcb *listen_unp)
  {
          cru2x(td->td_ucred, &client_unp->unp_peercred);
          client_unp->unp_flags |= UNP_HAVEPC;
  
          memcpy(&server_unp->unp_peercred, &listen_unp->unp_peercred,
              sizeof(server_unp->unp_peercred));
          server_unp->unp_flags |= UNP_HAVEPC;
          if (listen_unp->unp_flags & UNP_WANTCRED)
                  client_unp->unp_flags |= UNP_WANTCRED;
  }
  
  static int
  unp_connect2(struct socket *so, struct socket *so2, int req)
  {
          struct unpcb *unp;
          struct unpcb *unp2;
  
          unp = sotounpcb(so);
          KASSERT(unp != NULL, ("unp_connect2: unp == NULL"));
          unp2 = sotounpcb(so2);
          KASSERT(unp2 != NULL, ("unp_connect2: unp2 == NULL"));
  
          UNP_LINK_WLOCK_ASSERT();
          UNP_PCB_LOCK_ASSERT(unp);
          UNP_PCB_LOCK_ASSERT(unp2);
  
          if (so2->so_type != so->so_type)
                  return (EPROTOTYPE);
          unp2->unp_flags &= ~UNP_NASCENT;
          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:
          case SOCK_SEQPACKET:
                  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)
  {
          struct socket *so;
  
          KASSERT(unp2 != NULL, ("unp_disconnect: unp2 == NULL"));
  
          UNP_LINK_WLOCK_ASSERT();
          UNP_PCB_LOCK_ASSERT(unp);
          UNP_PCB_LOCK_ASSERT(unp2);
  
          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:
          case SOCK_SEQPACKET:
                  soisdisconnected(unp->unp_socket);
                  unp2->unp_conn = NULL;
                  soisdisconnected(unp2->unp_socket);
                  break;
          }
  }
  
  /*
   * unp_pcblist() walks the global list of struct unpcb's to generate a
   * pointer list, bumping the refcount on each unpcb.  It then copies them out
   * sequentially, validating the generation number on each to see if it has
   * been detached.  All of this is necessary because copyout() may sleep on
   * disk I/O.
   */
  static int
  unp_pcblist(SYSCTL_HANDLER_ARGS)
  {
          int error, i, n;
          int freeunp;
          struct unpcb *unp, **unp_list;
          unp_gen_t gencnt;
          struct xunpgen *xug;
          struct unp_head *head;
          struct xunpcb *xu;
  
          switch ((intptr_t)arg1) {
          case SOCK_STREAM:
                  head = &unp_shead;
                  break;
  
          case SOCK_DGRAM:
                  head = &unp_dhead;
                  break;
  
          case SOCK_SEQPACKET:
                  head = &unp_sphead;
                  break;
  
          default:
                  panic("unp_pcblist: arg1 %d", (int)(intptr_t)arg1);
          }
  
          /*
           * 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 | M_ZERO);
          UNP_LIST_LOCK();
          gencnt = unp_gencnt;
          n = unp_count;
          UNP_LIST_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_LIST_LOCK();
          for (unp = LIST_FIRST(head), i = 0; unp && i < n;
               unp = LIST_NEXT(unp, unp_link)) {
                  UNP_PCB_LOCK(unp);
                  if (unp->unp_gencnt <= gencnt) {
                          if (cr_cansee(req->td->td_ucred,
                              unp->unp_socket->so_cred)) {
                                  UNP_PCB_UNLOCK(unp);
                                  continue;
                          }
                          unp_list[i++] = unp;
                          unp->unp_refcount++;
                  }
                  UNP_PCB_UNLOCK(unp);
          }
          UNP_LIST_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];
                  UNP_PCB_LOCK(unp);
                  unp->unp_refcount--;
                  if (unp->unp_refcount != 0 && 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);
                          UNP_PCB_UNLOCK(unp);
                          error = SYSCTL_OUT(req, xu, sizeof *xu);
                  } else {
                          freeunp = (unp->unp_refcount == 0);
                          UNP_PCB_UNLOCK(unp);
                          if (freeunp) {
                                  UNP_PCB_LOCK_DESTROY(unp);
                                  uma_zfree(unp_zone, unp);
                          }
                  }
          }
          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, CTLTYPE_OPAQUE | CTLFLAG_RD,
      (void *)(intptr_t)SOCK_DGRAM, 0, unp_pcblist, "S,xunpcb",
      "List of active local datagram sockets");
  SYSCTL_PROC(_net_local_stream, OID_AUTO, pcblist, CTLTYPE_OPAQUE | CTLFLAG_RD,
      (void *)(intptr_t)SOCK_STREAM, 0, unp_pcblist, "S,xunpcb",
      "List of active local stream sockets");
  SYSCTL_PROC(_net_local_seqpacket, OID_AUTO, pcblist,
      CTLTYPE_OPAQUE | CTLFLAG_RD,
      (void *)(intptr_t)SOCK_SEQPACKET, 0, unp_pcblist, "S,xunpcb",
      "List of active local seqpacket sockets");
  
  static void
  unp_shutdown(struct unpcb *unp)
  {
          struct unpcb *unp2;
          struct socket *so;
  
          UNP_LINK_WLOCK_ASSERT();
          UNP_PCB_LOCK_ASSERT(unp);
  
          unp2 = unp->unp_conn;
          if ((unp->unp_socket->so_type == SOCK_STREAM ||
              (unp->unp_socket->so_type == SOCK_SEQPACKET)) && unp2 != NULL) {
                  so = unp2->unp_socket;
                  if (so != NULL)
                          socantrcvmore(so);
          }
  }
  
  static void
  unp_drop(struct unpcb *unp)
  {
          struct socket *so = unp->unp_socket;
          struct unpcb *unp2;
  
          UNP_LINK_WLOCK_ASSERT();
          UNP_PCB_LOCK_ASSERT(unp);
  
          /*
           * Regardless of whether the socket's peer dropped the connection
           * with this socket by aborting or disconnecting, POSIX requires
           * that ECONNRESET is returned.
           */
          so->so_error = ECONNRESET;
          unp2 = unp->unp_conn;
          if (unp2 == NULL)
                  return;
          UNP_PCB_LOCK(unp2);
          unp_disconnect(unp, unp2);
          UNP_PCB_UNLOCK(unp2);
  }
  
  static void
  unp_freerights(struct filedescent **fdep, int fdcount)
  {
          struct file *fp;
          int i;
  
          KASSERT(fdcount > 0, ("%s: fdcount %d", __func__, fdcount));
  
          for (i = 0; i < fdcount; i++) {
                  fp = fdep[i]->fde_file;
                  filecaps_free(&fdep[i]->fde_caps);
                  unp_discard(fp);
          }
          free(fdep[0], M_FILECAPS);
  }
  
  static int
  unp_externalize(struct mbuf *control, struct mbuf **controlp, int flags)
  {
          struct thread *td = curthread;          /* XXX */
          struct cmsghdr *cm = mtod(control, struct cmsghdr *);
          int i;
          int *fdp;
          struct filedesc *fdesc = td->td_proc->p_fd;
          struct filedescent **fdep;
          void *data;
          socklen_t clen = control->m_len, datalen;
          int error, newfds;
          u_int newlen;
  
          UNP_LINK_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(*fdep);
                          if (newfds == 0)
                                  goto next;
                          fdep = data;
  
                          /* If we're not outputting the descriptors free them. */
                          if (error || controlp == NULL) {
                                  unp_freerights(fdep, newfds);
                                  goto next;
                          }
                          FILEDESC_XLOCK(fdesc);
  
                          /*
                           * 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_XUNLOCK(fdesc);
                                  error = E2BIG;
                                  unp_freerights(fdep, newfds);
                                  goto next;
                          }
  
                          fdp = (int *)
                              CMSG_DATA(mtod(*controlp, struct cmsghdr *));
                          if (fdallocn(td, 0, fdp, newfds) != 0) {
                                  FILEDESC_XUNLOCK(fdesc);
                                  error = EMSGSIZE;
                                  unp_freerights(fdep, newfds);
                                  m_freem(*controlp);
                                  *controlp = NULL;
                                  goto next;
                          }
                          for (i = 0; i < newfds; i++, fdp++) {
                                  _finstall(fdesc, fdep[i]->fde_file, *fdp,
                                      (flags & MSG_CMSG_CLOEXEC) != 0 ? UF_EXCLOSE : 0,
                                      &fdep[i]->fde_caps);
                                  unp_externalize_fp(fdep[i]->fde_file);
                          }
  
                          /*
                           * The new type indicates that the mbuf data refers to
                           * kernel resources that may need to be released before
                           * the mbuf is freed.
                           */
                          m_chtype(*controlp, MT_EXTCONTROL);
                          FILEDESC_XUNLOCK(fdesc);
                          free(fdep[0], M_FILECAPS);
                  } 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);
  }
  
  static void
  unp_zone_change(void *tag)
  {
  
          uma_zone_set_max(unp_zone, maxsockets);
  }
  
  static void
  unp_init(void)
  {
  
  #ifdef VIMAGE
          if (!IS_DEFAULT_VNET(curvnet))
                  return;
  #endif
          unp_zone = uma_zcreate("unpcb", sizeof(struct unpcb), NULL, NULL,
              NULL, NULL, UMA_ALIGN_PTR, 0);
          if (unp_zone == NULL)
                  panic("unp_init");
          uma_zone_set_max(unp_zone, maxsockets);
          uma_zone_set_warning(unp_zone, "kern.ipc.maxsockets limit reached");
          EVENTHANDLER_REGISTER(maxsockets_change, unp_zone_change,
              NULL, EVENTHANDLER_PRI_ANY);
          LIST_INIT(&unp_dhead);
          LIST_INIT(&unp_shead);
          LIST_INIT(&unp_sphead);
          SLIST_INIT(&unp_defers);
          TIMEOUT_TASK_INIT(taskqueue_thread, &unp_gc_task, 0, unp_gc, NULL);
          TASK_INIT(&unp_defer_task, 0, unp_process_defers, NULL);
          UNP_LINK_LOCK_INIT();
          UNP_LIST_LOCK_INIT();
          UNP_DEFERRED_LOCK_INIT();
  }
  
  static void
  unp_internalize_cleanup_rights(struct mbuf *control)
  {
          struct cmsghdr *cp;
          struct mbuf *m;
          void *data;
          socklen_t datalen;
  
          for (m = control; m != NULL; m = m->m_next) {
                  cp = mtod(m, struct cmsghdr *);
                  if (cp->cmsg_level != SOL_SOCKET ||
                      cp->cmsg_type != SCM_RIGHTS)
                          continue;
                  data = CMSG_DATA(cp);
                  datalen = (caddr_t)cp + cp->cmsg_len - (caddr_t)data;
                  unp_freerights(data, datalen / sizeof(struct filedesc *));
          }
  }
  
  static int
  unp_internalize(struct mbuf **controlp, struct thread *td)
  {
          struct mbuf *control, **initial_controlp;
          struct proc *p;
          struct filedesc *fdesc;
          struct bintime *bt;
          struct cmsghdr *cm;
          struct cmsgcred *cmcred;
          struct filedescent *fde, **fdep, *fdev;
          struct file *fp;
          struct timeval *tv;
          struct timespec *ts;
          void *data;
          socklen_t clen, datalen;
          int i, error, *fdp, oldfds;
          u_int newlen;
  
          UNP_LINK_UNLOCK_ASSERT();
  
          p = td->td_proc;
          fdesc = p->p_fd;
          error = 0;
          control = *controlp;
          clen = control->m_len;
          *controlp = NULL;
          initial_controlp = controlp;
          for (cm = mtod(control, struct cmsghdr *); cm != NULL;) {
                  if (sizeof(*cm) > clen || cm->cmsg_level != SOL_SOCKET
                      || cm->cmsg_len > clen || cm->cmsg_len < sizeof(*cm)) {
                          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);
                          if (oldfds == 0)
                                  break;
                          /*
                           * Check that all the FDs passed in refer to legal
                           * files.  If not, reject the entire operation.
                           */
                          fdp = data;
                          FILEDESC_SLOCK(fdesc);
                          for (i = 0; i < oldfds; i++, fdp++) {
                                  fp = fget_locked(fdesc, *fdp);
                                  if (fp == NULL) {
                                          FILEDESC_SUNLOCK(fdesc);
                                          error = EBADF;
                                          goto out;
                                  }
                                  if (!(fp->f_ops->fo_flags & DFLAG_PASSABLE)) {
                                          FILEDESC_SUNLOCK(fdesc);
                                          error = EOPNOTSUPP;
                                          goto out;
                                  }
  
                          }
  
                          /*
                           * Now replace the integer FDs with pointers to the
                           * file structure and capability rights.
                           */
                          newlen = oldfds * sizeof(fdep[0]);
                          *controlp = sbcreatecontrol(NULL, newlen,
                              SCM_RIGHTS, SOL_SOCKET);
                          if (*controlp == NULL) {
                                  FILEDESC_SUNLOCK(fdesc);
                                  error = E2BIG;
                                  goto out;
                          }
                          fdp = data;
                          fdep = (struct filedescent **)
                              CMSG_DATA(mtod(*controlp, struct cmsghdr *));
                          fdev = malloc(sizeof(*fdev) * oldfds, M_FILECAPS,
                              M_WAITOK);
                          for (i = 0; i < oldfds; i++, fdev++, fdp++) {
                                  fde = &fdesc->fd_ofiles[*fdp];
                                  fdep[i] = fdev;
                                  fdep[i]->fde_file = fde->fde_file;
                                  filecaps_copy(&fde->fde_caps,
                                      &fdep[i]->fde_caps, true);
                                  unp_internalize_fp(fdep[i]->fde_file);
                          }
                          FILEDESC_SUNLOCK(fdesc);
                          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;
  
                  case SCM_BINTIME:
                          *controlp = sbcreatecontrol(NULL, sizeof(*bt),
                              SCM_BINTIME, SOL_SOCKET);
                          if (*controlp == NULL) {
                                  error = ENOBUFS;
                                  goto out;
                          }
                          bt = (struct bintime *)
                              CMSG_DATA(mtod(*controlp, struct cmsghdr *));
                          bintime(bt);
                          break;
  
                  case SCM_REALTIME:
                          *controlp = sbcreatecontrol(NULL, sizeof(*ts),
                              SCM_REALTIME, SOL_SOCKET);
                          if (*controlp == NULL) {
                                  error = ENOBUFS;
                                  goto out;
                          }
                          ts = (struct timespec *)
                              CMSG_DATA(mtod(*controlp, struct cmsghdr *));
                          nanotime(ts);
                          break;
  
                  case SCM_MONOTONIC:
                          *controlp = sbcreatecontrol(NULL, sizeof(*ts),
                              SCM_MONOTONIC, SOL_SOCKET);
                          if (*controlp == NULL) {
                                  error = ENOBUFS;
                                  goto out;
                          }
                          ts = (struct timespec *)
                              CMSG_DATA(mtod(*controlp, struct cmsghdr *));
                          nanouptime(ts);
                          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:
          if (error != 0 && initial_controlp != NULL)
                  unp_internalize_cleanup_rights(*initial_controlp);
          m_freem(control);
          return (error);
  }
  
  static struct mbuf *
  unp_addsockcred(struct thread *td, struct mbuf *control)
  {
          struct mbuf *m, *n, *n_prev;
          struct sockcred *sc;
          const struct cmsghdr *cm;
          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);
  
          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];
  
          /*
           * Unlink SCM_CREDS control messages (struct cmsgcred), since just
           * created SCM_CREDS control message (struct sockcred) has another
           * format.
           */
          if (control != NULL)
                  for (n = control, n_prev = NULL; n != NULL;) {
                          cm = mtod(n, struct cmsghdr *);
                          if (cm->cmsg_level == SOL_SOCKET &&
                              cm->cmsg_type == SCM_CREDS) {
                                  if (n_prev == NULL)
                                          control = n->m_next;
                                  else
                                          n_prev->m_next = n->m_next;
                                  n = m_free(n);
                          } else {
                                  n_prev = n;
                                  n = n->m_next;
                          }
                  }
  
          /* Prepend it to the head. */
          m->m_next = control;
          return (m);
  }
  
  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 != &localdomain)
                  return (NULL);
          return sotounpcb(so);
  }
  
  static void
  unp_discard(struct file *fp)
  {
          struct unp_defer *dr;
  
          if (unp_externalize_fp(fp)) {
                  dr = malloc(sizeof(*dr), M_TEMP, M_WAITOK);
                  dr->ud_fp = fp;
                  UNP_DEFERRED_LOCK();
                  SLIST_INSERT_HEAD(&unp_defers, dr, ud_link);
                  UNP_DEFERRED_UNLOCK();
                  atomic_add_int(&unp_defers_count, 1);
                  taskqueue_enqueue(taskqueue_thread, &unp_defer_task);
          } else
                  (void) closef(fp, (struct thread *)NULL);
  }
  
  static void
  unp_process_defers(void *arg __unused, int pending)
  {
          struct unp_defer *dr;
          SLIST_HEAD(, unp_defer) drl;
          int count;
  
          SLIST_INIT(&drl);
          for (;;) {
                  UNP_DEFERRED_LOCK();
                  if (SLIST_FIRST(&unp_defers) == NULL) {
                          UNP_DEFERRED_UNLOCK();
                          break;
                  }
                  SLIST_SWAP(&unp_defers, &drl, unp_defer);
                  UNP_DEFERRED_UNLOCK();
                  count = 0;
                  while ((dr = SLIST_FIRST(&drl)) != NULL) {
                          SLIST_REMOVE_HEAD(&drl, ud_link);
                          closef(dr->ud_fp, NULL);
                          free(dr, M_TEMP);
                          count++;
                  }
                  atomic_add_int(&unp_defers_count, -count);
          }
  }
  
  static void
  unp_internalize_fp(struct file *fp)
  {
          struct unpcb *unp;
  
          UNP_LINK_WLOCK();
          if ((unp = fptounp(fp)) != NULL) {
                  unp->unp_file = fp;
                  unp->unp_msgcount++;
          }
          fhold(fp);
          unp_rights++;
          UNP_LINK_WUNLOCK();
  }
  
  static int
  unp_externalize_fp(struct file *fp)
  {
          struct unpcb *unp;
          int ret;
  
          UNP_LINK_WLOCK();
          if ((unp = fptounp(fp)) != NULL) {
                  unp->unp_msgcount--;
                  ret = 1;
          } else
                  ret = 0;
          unp_rights--;
          UNP_LINK_WUNLOCK();
          return (ret);
  }
  
  /*
   * 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_marked;
  static int      unp_unreachable;
  
  static void
  unp_accessable(struct filedescent **fdep, int fdcount)
  {
          struct unpcb *unp;
          struct file *fp;
          int i;
  
          for (i = 0; i < fdcount; i++) {
                  fp = fdep[i]->fde_file;
                  if ((unp = fptounp(fp)) == NULL)
                          continue;
                  if (unp->unp_gcflag & UNPGC_REF)
                          continue;
                  unp->unp_gcflag &= ~UNPGC_DEAD;
                  unp->unp_gcflag |= UNPGC_REF;
                  unp_marked++;
          }
  }
  
  static void
  unp_gc_process(struct unpcb *unp)
  {
          struct socket *soa;
          struct socket *so;
          struct file *fp;
  
          /* Already processed. */
          if (unp->unp_gcflag & UNPGC_SCANNED)
                  return;
          fp = unp->unp_file;
  
          /*
           * Check for a socket potentially in a cycle.  It must be in a
           * queue as indicated by msgcount, and this must equal the file
           * reference count.  Note that when msgcount is 0 the file is NULL.
           */
          if ((unp->unp_gcflag & UNPGC_REF) == 0 && fp &&
              unp->unp_msgcount != 0 && fp->f_count == unp->unp_msgcount) {
                  unp->unp_gcflag |= UNPGC_DEAD;
                  unp_unreachable++;
                  return;
          }
  
          /*
           * Mark all sockets we reference with RIGHTS.
           */
          so = unp->unp_socket;
          if ((unp->unp_gcflag & UNPGC_IGNORE_RIGHTS) == 0) {
                  SOCKBUF_LOCK(&so->so_rcv);
                  unp_scan(so->so_rcv.sb_mb, unp_accessable);
                  SOCKBUF_UNLOCK(&so->so_rcv);
          }
  
          /*
           * Mark all sockets in our accept queue.
           */
          ACCEPT_LOCK();
          TAILQ_FOREACH(soa, &so->so_comp, so_list) {
                  if ((sotounpcb(soa)->unp_gcflag & UNPGC_IGNORE_RIGHTS) != 0)
                          continue;
                  SOCKBUF_LOCK(&soa->so_rcv);
                  unp_scan(soa->so_rcv.sb_mb, unp_accessable);
                  SOCKBUF_UNLOCK(&soa->so_rcv);
          }
          ACCEPT_UNLOCK();
          unp->unp_gcflag |= UNPGC_SCANNED;
  }
  
  static int unp_recycled;
  SYSCTL_INT(_net_local, OID_AUTO, recycled, CTLFLAG_RD, &unp_recycled, 0, 
      "Number of unreachable sockets claimed by the garbage collector.");
  
  static int unp_taskcount;
  SYSCTL_INT(_net_local, OID_AUTO, taskcount, CTLFLAG_RD, &unp_taskcount, 0, 
      "Number of times the garbage collector has run.");
  
  static void
  unp_gc(__unused void *arg, int pending)
  {
          struct unp_head *heads[] = { &unp_dhead, &unp_shead, &unp_sphead,
                                      NULL };
          struct unp_head **head;
          struct file *f, **unref;
          struct unpcb *unp;
          int i, total;
  
          unp_taskcount++;
          UNP_LIST_LOCK();
          /*
           * First clear all gc flags from previous runs, apart from
           * UNPGC_IGNORE_RIGHTS.
           */
          for (head = heads; *head != NULL; head++)
                  LIST_FOREACH(unp, *head, unp_link)
                          unp->unp_gcflag =
                              (unp->unp_gcflag & UNPGC_IGNORE_RIGHTS);
  
          /*
           * Scan marking all reachable sockets with UNPGC_REF.  Once a socket
           * is reachable all of the sockets it references are reachable.
           * Stop the scan once we do a complete loop without discovering
           * a new reachable socket.
           */
          do {
                  unp_unreachable = 0;
                  unp_marked = 0;
                  for (head = heads; *head != NULL; head++)
                          LIST_FOREACH(unp, *head, unp_link)
                                  unp_gc_process(unp);
          } while (unp_marked);
          UNP_LIST_UNLOCK();
          if (unp_unreachable == 0)
                  return;
  
          /*
           * Allocate space for a local list of dead unpcbs.
           */
          unref = malloc(unp_unreachable * sizeof(struct file *),
              M_TEMP, M_WAITOK);
  
          /*
           * Iterate looking for sockets which have been specifically marked
           * as as unreachable and store them locally.
           */
          UNP_LINK_RLOCK();
          UNP_LIST_LOCK();
          for (total = 0, head = heads; *head != NULL; head++)
                  LIST_FOREACH(unp, *head, unp_link)
                          if ((unp->unp_gcflag & UNPGC_DEAD) != 0) {
                                  f = unp->unp_file;
                                  if (unp->unp_msgcount == 0 || f == NULL ||
                                      f->f_count != unp->unp_msgcount)
                                          continue;
                                  unref[total++] = f;
                                  fhold(f);
                                  KASSERT(total <= unp_unreachable,
                                      ("unp_gc: incorrect unreachable count."));
                          }
          UNP_LIST_UNLOCK();
          UNP_LINK_RUNLOCK();
  
          /*
           * Now flush all sockets, free'ing rights.  This will free the
           * struct files associated with these sockets but leave each socket
           * with one remaining ref.
           */
          for (i = 0; i < total; i++) {
                  struct socket *so;
  
                  so = unref[i]->f_data;
                  CURVNET_SET(so->so_vnet);
                  sorflush(so);
                  CURVNET_RESTORE();
          }
  
          /*
           * And finally release the sockets so they can be reclaimed.
           */
          for (i = 0; i < total; i++)
                  fdrop(unref[i], NULL);
          unp_recycled += total;
          free(unref, M_TEMP);
  }
  
  static void
  unp_dispose(struct mbuf *m)
  {
  
          if (m)
                  unp_scan(m, unp_freerights);
  }
  
  /*
   * Synchronize against unp_gc, which can trip over data as we are freeing it.
   */
  static void
  unp_dispose_so(struct socket *so)
  {
          struct unpcb *unp;
  
          unp = sotounpcb(so);
          UNP_LIST_LOCK();
          unp->unp_gcflag |= UNPGC_IGNORE_RIGHTS;
          UNP_LIST_UNLOCK();
          unp_dispose(so->so_rcv.sb_mb);
  }
  
  static void
  unp_scan(struct mbuf *m0, void (*op)(struct filedescent **, int))
  {
          struct mbuf *m;
          struct cmsghdr *cm;
          void *data;
          socklen_t clen, datalen;
  
          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) {
                                          (*op)(data, datalen /
                                              sizeof(struct filedescent *));
                                  }
  
                                  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_nextpkt;
          }
  }
  
  /*
   * A helper function called by VFS before socket-type vnode reclamation.
   * For an active vnode it clears unp_vnode pointer and decrements unp_vnode
   * use count.
   */
  void
  vfs_unp_reclaim(struct vnode *vp)
  {
          struct socket *so;
          struct unpcb *unp;
          int active;
  
          ASSERT_VOP_ELOCKED(vp, "vfs_unp_reclaim");
          KASSERT(vp->v_type == VSOCK,
              ("vfs_unp_reclaim: vp->v_type != VSOCK"));
  
          active = 0;
          UNP_LINK_WLOCK();
          VOP_UNP_CONNECT(vp, &so);
          if (so == NULL)
                  goto done;
          unp = sotounpcb(so);
          if (unp == NULL)
                  goto done;
          UNP_PCB_LOCK(unp);
          if (unp->unp_vnode == vp) {
                  VOP_UNP_DETACH(vp);
                  unp->unp_vnode = NULL;
                  active = 1;
          }
          UNP_PCB_UNLOCK(unp);
  done:
          UNP_LINK_WUNLOCK();
          if (active)
                  vunref(vp);
  }
  
  #ifdef DDB
  static void
  db_print_indent(int indent)
  {
          int i;
  
          for (i = 0; i < indent; i++)
                  db_printf(" ");
  }
  
  static void
  db_print_unpflags(int unp_flags)
  {
          int comma;
  
          comma = 0;
          if (unp_flags & UNP_HAVEPC) {
                  db_printf("%sUNP_HAVEPC", comma ? ", " : "");
                  comma = 1;
          }
          if (unp_flags & UNP_HAVEPCCACHED) {
                  db_printf("%sUNP_HAVEPCCACHED", comma ? ", " : "");
                  comma = 1;
          }
          if (unp_flags & UNP_WANTCRED) {
                  db_printf("%sUNP_WANTCRED", comma ? ", " : "");
                  comma = 1;
          }
          if (unp_flags & UNP_CONNWAIT) {
                  db_printf("%sUNP_CONNWAIT", comma ? ", " : "");
                  comma = 1;
          }
          if (unp_flags & UNP_CONNECTING) {
                  db_printf("%sUNP_CONNECTING", comma ? ", " : "");
                  comma = 1;
          }
          if (unp_flags & UNP_BINDING) {
                  db_printf("%sUNP_BINDING", comma ? ", " : "");
                  comma = 1;
          }
  }
  
  static void
  db_print_xucred(int indent, struct xucred *xu)
  {
          int comma, i;
  
          db_print_indent(indent);
          db_printf("cr_version: %u   cr_uid: %u   cr_ngroups: %d\n",
              xu->cr_version, xu->cr_uid, xu->cr_ngroups);
          db_print_indent(indent);
          db_printf("cr_groups: ");
          comma = 0;
          for (i = 0; i < xu->cr_ngroups; i++) {
                  db_printf("%s%u", comma ? ", " : "", xu->cr_groups[i]);
                  comma = 1;
          }
          db_printf("\n");
  }
  
  static void
  db_print_unprefs(int indent, struct unp_head *uh)
  {
          struct unpcb *unp;
          int counter;
  
          counter = 0;
          LIST_FOREACH(unp, uh, unp_reflink) {
                  if (counter % 4 == 0)
                          db_print_indent(indent);
                  db_printf("%p  ", unp);
                  if (counter % 4 == 3)
                          db_printf("\n");
                  counter++;
          }
          if (counter != 0 && counter % 4 != 0)
                  db_printf("\n");
  }
  
  DB_SHOW_COMMAND(unpcb, db_show_unpcb)
  {
          struct unpcb *unp;
  
          if (!have_addr) {
                  db_printf("usage: show unpcb <addr>\n");
                  return;
          }
          unp = (struct unpcb *)addr;
  
          db_printf("unp_socket: %p   unp_vnode: %p\n", unp->unp_socket,
              unp->unp_vnode);
  
          db_printf("unp_ino: %ju   unp_conn: %p\n", (uintmax_t)unp->unp_ino,
              unp->unp_conn);
  
          db_printf("unp_refs:\n");
          db_print_unprefs(2, &unp->unp_refs);
  
          /* XXXRW: Would be nice to print the full address, if any. */
          db_printf("unp_addr: %p\n", unp->unp_addr);
  
          db_printf("unp_gencnt: %llu\n",
              (unsigned long long)unp->unp_gencnt);
  
          db_printf("unp_flags: %x (", unp->unp_flags);
          db_print_unpflags(unp->unp_flags);
          db_printf(")\n");
  
          db_printf("unp_peercred:\n");
          db_print_xucred(2, &unp->unp_peercred);
  
          db_printf("unp_refcount: %u\n", unp->unp_refcount);
  }
  #endif

Cache object: dda053d06458a539ddd03ac28da577de