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NetBSD/sys/kern/uipc_usrreq.c
thorpej 1351e629b3 Several small changes to eliminate kludginess in dealing with unix domain 
socket names:
- In unp_setsockaddr() and unp_setpeeraddr(), if the socket name can't
  fit into a single mbuf, allocate enough external storage space to
  hold it.
- In unp_bind() and unp_connect(), perform a similar operation, but allocate
  one extra byte, and ensure that the pathname is nul-terminated.
Many thanks to enami tsugutomo <enami@cv.sony.co.jp> for the sanity
checking.
1997-06-26 06:06:40 +00:00

952 lines
22 KiB
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Raw Blame History

/* $NetBSD: uipc_usrreq.c,v 1.27 1997/06/26 06:06:40 thorpej Exp $ */
/*
* Copyright (c) 1997 Christopher G. Demetriou. All rights reserved.
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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.
*
* @(#)uipc_usrreq.c 8.3 (Berkeley) 1/4/94
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/filedesc.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/unpcb.h>
#include <sys/un.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/mbuf.h>
/*
* Unix communications domain.
*
* TODO:
* SEQPACKET, RDM
* rethink name space problems
* need a proper out-of-band
*/
struct sockaddr_un sun_noname = { sizeof(sun_noname), AF_UNIX };
ino_t unp_ino; /* prototype for fake inode numbers */
int
unp_output(m, control, unp)
struct mbuf *m, *control;
struct unpcb *unp;
{
struct socket *so2;
struct sockaddr_un *sun;
so2 = unp->unp_conn->unp_socket;
if (unp->unp_addr)
sun = unp->unp_addr;
else
sun = &sun_noname;
if (sbappendaddr(&so2->so_rcv, (struct sockaddr *)sun, m,
control) == 0) {
m_freem(control);
m_freem(m);
return (EINVAL);
} else {
sorwakeup(so2);
return (0);
}
}
void
unp_setsockaddr(unp, nam)
register struct unpcb *unp;
struct mbuf *nam;
{
struct sockaddr_un *sun;
if (unp->unp_addr)
sun = unp->unp_addr;
else
sun = &sun_noname;
nam->m_len = sun->sun_len;
if (nam->m_len > MLEN)
MEXTMALLOC(nam, nam->m_len, M_WAITOK);
bcopy(sun, mtod(nam, caddr_t), (size_t)nam->m_len);
}
void
unp_setpeeraddr(unp, nam)
register struct unpcb *unp;
struct mbuf *nam;
{
struct sockaddr_un *sun;
if (unp->unp_conn && unp->unp_conn->unp_addr)
sun = unp->unp_conn->unp_addr;
else
sun = &sun_noname;
nam->m_len = sun->sun_len;
if (nam->m_len > MLEN)
MEXTMALLOC(nam, nam->m_len, M_WAITOK);
bcopy(sun, mtod(nam, caddr_t), (size_t)nam->m_len);
}
/*ARGSUSED*/
int
uipc_usrreq(so, req, m, nam, control, p)
struct socket *so;
int req;
struct mbuf *m, *nam, *control;
struct proc *p;
{
struct unpcb *unp = sotounpcb(so);
register struct socket *so2;
register int error = 0;
if (req == PRU_CONTROL)
return (EOPNOTSUPP);
#ifdef DIAGNOSTIC
if (req != PRU_SEND && req != PRU_SENDOOB && control)
panic("uipc_usrreq: unexpected control mbuf");
#endif
if (unp == 0 && req != PRU_ATTACH) {
error = EINVAL;
goto release;
}
switch (req) {
case PRU_ATTACH:
if (unp != 0) {
error = EISCONN;
break;
}
error = unp_attach(so);
break;
case PRU_DETACH:
unp_detach(unp);
break;
case PRU_BIND:
error = unp_bind(unp, nam, p);
break;
case PRU_LISTEN:
if (unp->unp_vnode == 0)
error = EINVAL;
break;
case PRU_CONNECT:
error = unp_connect(so, nam, p);
break;
case PRU_CONNECT2:
error = unp_connect2(so, (struct socket *)nam);
break;
case PRU_DISCONNECT:
unp_disconnect(unp);
break;
case PRU_ACCEPT:
unp_setpeeraddr(unp, nam);
break;
case PRU_SHUTDOWN:
socantsendmore(so);
unp_shutdown(unp);
break;
case PRU_RCVD:
switch (so->so_type) {
case SOCK_DGRAM:
panic("uipc 1");
/*NOTREACHED*/
case SOCK_STREAM:
#define rcv (&so->so_rcv)
#define snd (&so2->so_snd)
if (unp->unp_conn == 0)
break;
so2 = unp->unp_conn->unp_socket;
/*
* Adjust backpressure on sender
* and wakeup any waiting to write.
*/
snd->sb_mbmax += unp->unp_mbcnt - rcv->sb_mbcnt;
unp->unp_mbcnt = rcv->sb_mbcnt;
snd->sb_hiwat += unp->unp_cc - rcv->sb_cc;
unp->unp_cc = rcv->sb_cc;
sowwakeup(so2);
#undef snd
#undef rcv
break;
default:
panic("uipc 2");
}
break;
case PRU_SEND:
if (control && (error = unp_internalize(control, p)))
break;
switch (so->so_type) {
case SOCK_DGRAM: {
if (nam) {
if ((so->so_state & SS_ISCONNECTED) != 0) {
error = EISCONN;
goto die;
}
error = unp_connect(so, nam, p);
if (error) {
die:
m_freem(control);
m_freem(m);
break;
}
} else {
if ((so->so_state & SS_ISCONNECTED) == 0) {
error = ENOTCONN;
goto die;
}
}
error = unp_output(m, control, unp);
if (nam)
unp_disconnect(unp);
break;
}
case SOCK_STREAM:
#define rcv (&so2->so_rcv)
#define snd (&so->so_snd)
if (unp->unp_conn == 0)
panic("uipc 3");
so2 = unp->unp_conn->unp_socket;
/*
* Send to paired receive port, and then reduce
* send buffer hiwater marks to maintain backpressure.
* Wake up readers.
*/
if (control) {
if (sbappendcontrol(rcv, m, control) == 0)
m_freem(control);
} else
sbappend(rcv, m);
snd->sb_mbmax -=
rcv->sb_mbcnt - unp->unp_conn->unp_mbcnt;
unp->unp_conn->unp_mbcnt = rcv->sb_mbcnt;
snd->sb_hiwat -= rcv->sb_cc - unp->unp_conn->unp_cc;
unp->unp_conn->unp_cc = rcv->sb_cc;
sorwakeup(so2);
#undef snd
#undef rcv
break;
default:
panic("uipc 4");
}
break;
case PRU_ABORT:
unp_drop(unp, ECONNABORTED);
break;
case PRU_SENSE:
((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat;
if (so->so_type == SOCK_STREAM && unp->unp_conn != 0) {
so2 = unp->unp_conn->unp_socket;
((struct stat *) m)->st_blksize += so2->so_rcv.sb_cc;
}
((struct stat *) m)->st_dev = NODEV;
if (unp->unp_ino == 0)
unp->unp_ino = unp_ino++;
((struct stat *) m)->st_atimespec =
((struct stat *) m)->st_mtimespec =
((struct stat *) m)->st_ctimespec = unp->unp_ctime;
((struct stat *) m)->st_ino = unp->unp_ino;
return (0);
case PRU_RCVOOB:
error = EOPNOTSUPP;
break;
case PRU_SENDOOB:
m_freem(control);
m_freem(m);
error = EOPNOTSUPP;
break;
case PRU_SOCKADDR:
unp_setsockaddr(unp, nam);
break;
case PRU_PEERADDR:
unp_setpeeraddr(unp, nam);
break;
default:
panic("piusrreq");
}
release:
return (error);
}
/*
* Both send and receive buffers are allocated PIPSIZ bytes of buffering
* for stream sockets, although the total for sender and receiver is
* actually only PIPSIZ.
* Datagram sockets really use the sendspace as the maximum datagram size,
* and don't really want to reserve the sendspace. Their recvspace should
* be large enough for at least one max-size datagram plus address.
*/
#define PIPSIZ 4096
u_long unpst_sendspace = PIPSIZ;
u_long unpst_recvspace = PIPSIZ;
u_long unpdg_sendspace = 2*1024; /* really max datagram size */
u_long unpdg_recvspace = 4*1024;
int unp_rights; /* file descriptors in flight */
int
unp_attach(so)
struct socket *so;
{
register struct unpcb *unp;
struct timeval tv;
int error;
if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
switch (so->so_type) {
case SOCK_STREAM:
error = soreserve(so, unpst_sendspace, unpst_recvspace);
break;
case SOCK_DGRAM:
error = soreserve(so, unpdg_sendspace, unpdg_recvspace);
break;
default:
panic("unp_attach");
}
if (error)
return (error);
}
unp = malloc(sizeof(*unp), M_PCB, M_NOWAIT);
if (unp == NULL)
return (ENOBUFS);
bzero((caddr_t)unp, sizeof(*unp));
unp->unp_socket = so;
so->so_pcb = unp;
microtime(&tv);
TIMEVAL_TO_TIMESPEC(&tv, &unp->unp_ctime);
return (0);
}
void
unp_detach(unp)
register struct unpcb *unp;
{
if (unp->unp_vnode) {
unp->unp_vnode->v_socket = 0;
vrele(unp->unp_vnode);
unp->unp_vnode = 0;
}
if (unp->unp_conn)
unp_disconnect(unp);
while (unp->unp_refs)
unp_drop(unp->unp_refs, ECONNRESET);
soisdisconnected(unp->unp_socket);
unp->unp_socket->so_pcb = 0;
if (unp->unp_addr)
free(unp->unp_addr, M_SONAME);
if (unp_rights) {
/*
* Normally the receive buffer is flushed later,
* in sofree, but if our receive buffer holds references
* to descriptors that are now garbage, we will dispose
* of those descriptor references after the garbage collector
* gets them (resulting in a "panic: closef: count < 0").
*/
sorflush(unp->unp_socket);
free(unp, M_PCB);
unp_gc();
} else
free(unp, M_PCB);
}
int
unp_bind(unp, nam, p)
struct unpcb *unp;
struct mbuf *nam;
struct proc *p;
{
struct sockaddr_un *sun;
register struct vnode *vp;
struct vattr vattr;
size_t addrlen;
int error;
struct nameidata nd;
if (unp->unp_vnode != 0)
return (EINVAL);
/*
* Allocate the new sockaddr. We have to allocate one
* extra byte so that we can ensure that the pathname
* is nul-terminated.
*/
addrlen = nam->m_len + 1;
sun = malloc(addrlen, M_SONAME, M_WAITOK);
m_copydata(nam, 0, nam->m_len, (caddr_t)sun);
*(((char *)sun) + nam->m_len) = '\0';
NDINIT(&nd, CREATE, FOLLOW | LOCKPARENT, UIO_SYSSPACE,
sun->sun_path, p);
/* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */
if ((error = namei(&nd)) != 0)
goto bad;
vp = nd.ni_vp;
if (vp != NULL) {
VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd);
if (nd.ni_dvp == vp)
vrele(nd.ni_dvp);
else
vput(nd.ni_dvp);
vrele(vp);
error = EADDRINUSE;
goto bad;
}
VATTR_NULL(&vattr);
vattr.va_type = VSOCK;
vattr.va_mode = ACCESSPERMS;
VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE);
error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr);
if (error)
goto bad;
vp = nd.ni_vp;
vp->v_socket = unp->unp_socket;
unp->unp_vnode = vp;
unp->unp_addrlen = addrlen;
unp->unp_addr = sun;
VOP_UNLOCK(vp);
return (0);
bad:
free(sun, M_SONAME);
return (error);
}
int
unp_connect(so, nam, p)
struct socket *so;
struct mbuf *nam;
struct proc *p;
{
register struct sockaddr_un *sun;
register struct vnode *vp;
register struct socket *so2, *so3;
struct unpcb *unp2, *unp3;
size_t addrlen;
int error;
struct nameidata nd;
/*
* Allocate a temporary sockaddr. We have to allocate one extra
* byte so that we can ensure that the pathname is nul-terminated.
* When we establish the connection, we copy the other PCB's
* sockaddr to our own.
*/
addrlen = nam->m_len + 1;
sun = malloc(addrlen, M_SONAME, M_WAITOK);
m_copydata(nam, 0, nam->m_len, (caddr_t)sun);
*(((char *)sun) + nam->m_len) = '\0';
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, sun->sun_path, p);
if ((error = namei(&nd)) != 0)
goto bad2;
vp = nd.ni_vp;
if (vp->v_type != VSOCK) {
error = ENOTSOCK;
goto bad;
}
if ((error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p)) != 0)
goto bad;
so2 = vp->v_socket;
if (so2 == 0) {
error = ECONNREFUSED;
goto bad;
}
if (so->so_type != so2->so_type) {
error = EPROTOTYPE;
goto bad;
}
if (so->so_proto->pr_flags & PR_CONNREQUIRED) {
if ((so2->so_options & SO_ACCEPTCONN) == 0 ||
(so3 = sonewconn(so2, 0)) == 0) {
error = ECONNREFUSED;
goto bad;
}
unp2 = sotounpcb(so2);
unp3 = sotounpcb(so3);
if (unp2->unp_addr) {
unp3->unp_addr = malloc(unp2->unp_addrlen,
M_SONAME, M_WAITOK);
bcopy(unp2->unp_addr, unp3->unp_addr,
unp2->unp_addrlen);
unp3->unp_addrlen = unp2->unp_addrlen;
}
so2 = so3;
}
error = unp_connect2(so, so2);
bad:
vput(vp);
bad2:
free(sun, M_SONAME);
return (error);
}
int
unp_connect2(so, so2)
register struct socket *so;
register struct socket *so2;
{
register struct unpcb *unp = sotounpcb(so);
register struct unpcb *unp2;
if (so2->so_type != so->so_type)
return (EPROTOTYPE);
unp2 = sotounpcb(so2);
unp->unp_conn = unp2;
switch (so->so_type) {
case SOCK_DGRAM:
unp->unp_nextref = unp2->unp_refs;
unp2->unp_refs = unp;
soisconnected(so);
break;
case SOCK_STREAM:
unp2->unp_conn = unp;
soisconnected(so);
soisconnected(so2);
break;
default:
panic("unp_connect2");
}
return (0);
}
void
unp_disconnect(unp)
struct unpcb *unp;
{
register struct unpcb *unp2 = unp->unp_conn;
if (unp2 == 0)
return;
unp->unp_conn = 0;
switch (unp->unp_socket->so_type) {
case SOCK_DGRAM:
if (unp2->unp_refs == unp)
unp2->unp_refs = unp->unp_nextref;
else {
unp2 = unp2->unp_refs;
for (;;) {
if (unp2 == 0)
panic("unp_disconnect");
if (unp2->unp_nextref == unp)
break;
unp2 = unp2->unp_nextref;
}
unp2->unp_nextref = unp->unp_nextref;
}
unp->unp_nextref = 0;
unp->unp_socket->so_state &= ~SS_ISCONNECTED;
break;
case SOCK_STREAM:
soisdisconnected(unp->unp_socket);
unp2->unp_conn = 0;
soisdisconnected(unp2->unp_socket);
break;
}
}
#ifdef notdef
unp_abort(unp)
struct unpcb *unp;
{
unp_detach(unp);
}
#endif
void
unp_shutdown(unp)
struct unpcb *unp;
{
struct socket *so;
if (unp->unp_socket->so_type == SOCK_STREAM && unp->unp_conn &&
(so = unp->unp_conn->unp_socket))
socantrcvmore(so);
}
void
unp_drop(unp, errno)
struct unpcb *unp;
int errno;
{
struct socket *so = unp->unp_socket;
so->so_error = errno;
unp_disconnect(unp);
if (so->so_head) {
so->so_pcb = 0;
sofree(so);
if (unp->unp_addr)
free(unp->unp_addr, M_SONAME);
free(unp, M_PCB);
}
}
#ifdef notdef
unp_drain()
{
}
#endif
int
unp_externalize(rights)
struct mbuf *rights;
{
struct proc *p = curproc; /* XXX */
register struct cmsghdr *cm = mtod(rights, struct cmsghdr *);
register int i, *fdp = (int *)(cm + 1);
register struct file **rp = (struct file **)ALIGN(cm + 1);
register struct file *fp;
int nfds = (cm->cmsg_len - ALIGN(sizeof(*cm))) / sizeof (struct file *);
int f;
/* Make sure that the recipient has space */
if (!fdavail(p, nfds)) {
for (i = 0; i < nfds; i++) {
fp = *rp;
unp_discard(fp);
*rp++ = 0;
}
return (EMSGSIZE);
}
/*
* Add file to the recipient's open file table, converting them
* to integer file descriptors as we go. Done in forward order
* because an integer will always come in the same place or before
* its corresponding struct file pointer.
*/
for (i = 0; i < nfds; i++) {
if (fdalloc(p, 0, &f))
panic("unp_externalize");
fp = *rp;
p->p_fd->fd_ofiles[f] = fp;
fp->f_msgcount--;
unp_rights--;
*fdp++ = f;
}
/*
* Adjust length, in case of transition from large struct file
* pointers to ints.
*/
cm->cmsg_len = sizeof(*cm) + (nfds * sizeof(int));
rights->m_len = cm->cmsg_len;
return (0);
}
int
unp_internalize(control, p)
struct mbuf *control;
struct proc *p;
{
struct filedesc *fdescp = p->p_fd;
register struct cmsghdr *cm = mtod(control, struct cmsghdr *);
register struct file **rp;
register struct file *fp;
register int i, fd, *fdp;
int nfds;
u_int neededspace;
/* Sanity check the control message header */
if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET ||
cm->cmsg_len != control->m_len)
return (EINVAL);
/* Verify that the file descriptors are valid */
nfds = (cm->cmsg_len - sizeof (*cm)) / sizeof (int);
fdp = (int *)(cm + 1);
for (i = 0; i < nfds; i++) {
fd = *fdp++;
if ((unsigned)fd >= fdescp->fd_nfiles ||
fdescp->fd_ofiles[fd] == NULL)
return (EBADF);
}
/* Make sure we have room for the struct file pointers */
morespace:
neededspace = (ALIGN(sizeof (*cm)) + nfds * sizeof (struct file *)) -
control->m_len;
if (neededspace > M_TRAILINGSPACE(control)) {
/* if we already have a cluster, the message is just too big */
if (control->m_flags & M_EXT)
return (E2BIG);
/* allocate a cluster and try again */
MCLGET(control, M_WAIT);
if ((control->m_flags & M_EXT) == 0)
return (ENOBUFS); /* allocation failed */
/* copy the data to the cluster */
bcopy(cm, mtod(control, char *), cm->cmsg_len);
cm = mtod(control, struct cmsghdr *);
goto morespace;
}
/* adjust message & mbuf to note amount of space actually used. */
cm->cmsg_len += neededspace;
control->m_len = cm->cmsg_len;
/*
* Transform the file descriptors into struct file pointers, in
* reverse order so that if pointers are bigger than ints, the
* int won't get until we're done.
*/
fdp = ((int *)(cm + 1)) + nfds - 1;
rp = ((struct file **)ALIGN(cm + 1)) + nfds - 1;
for (i = 0; i < nfds; i++) {
fp = fdescp->fd_ofiles[*fdp];
*rp-- = fp;
fp->f_count++;
fp->f_msgcount++;
unp_rights++;
}
return (0);
}
int unp_defer, unp_gcing;
extern struct domain unixdomain;
void
unp_gc()
{
register struct file *fp, *nextfp;
register struct socket *so;
struct file **extra_ref, **fpp;
int nunref, i;
if (unp_gcing)
return;
unp_gcing = 1;
unp_defer = 0;
for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next)
fp->f_flag &= ~(FMARK|FDEFER);
do {
for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) {
if (fp->f_count == 0)
continue;
if (fp->f_flag & FDEFER) {
fp->f_flag &= ~FDEFER;
unp_defer--;
} else {
if (fp->f_flag & FMARK)
continue;
if (fp->f_count == fp->f_msgcount)
continue;
fp->f_flag |= FMARK;
}
if (fp->f_type != DTYPE_SOCKET ||
(so = (struct socket *)fp->f_data) == 0)
continue;
if (so->so_proto->pr_domain != &unixdomain ||
(so->so_proto->pr_flags&PR_RIGHTS) == 0)
continue;
#ifdef notdef
if (so->so_rcv.sb_flags & SB_LOCK) {
/*
* This is problematical; it's not clear
* we need to wait for the sockbuf to be
* unlocked (on a uniprocessor, at least),
* and it's also not clear what to do
* if sbwait returns an error due to receipt
* of a signal. If sbwait does return
* an error, we'll go into an infinite
* loop. Delete all of this for now.
*/
(void) sbwait(&so->so_rcv);
goto restart;
}
#endif
unp_scan(so->so_rcv.sb_mb, unp_mark);
}
} while (unp_defer);
/*
* We grab an extra reference to each of the file table entries
* that are not otherwise accessible and then free the rights
* that are stored in messages on them.
*
* The bug in the orginal code is a little tricky, so I'll describe
* what's wrong with it here.
*
* It is incorrect to simply unp_discard each entry for f_msgcount
* times -- consider the case of sockets A and B that contain
* references to each other. On a last close of some other socket,
* we trigger a gc since the number of outstanding rights (unp_rights)
* is non-zero. If during the sweep phase the gc code un_discards,
* we end up doing a (full) closef on the descriptor. A closef on A
* results in the following chain. Closef calls soo_close, which
* calls soclose. Soclose calls first (through the switch
* uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply
* returns because the previous instance had set unp_gcing, and
* we return all the way back to soclose, which marks the socket
* with SS_NOFDREF, and then calls sofree. Sofree calls sorflush
* to free up the rights that are queued in messages on the socket A,
* i.e., the reference on B. The sorflush calls via the dom_dispose
* switch unp_dispose, which unp_scans with unp_discard. This second
* instance of unp_discard just calls closef on B.
*
* Well, a similar chain occurs on B, resulting in a sorflush on B,
* which results in another closef on A. Unfortunately, A is already
* being closed, and the descriptor has already been marked with
* SS_NOFDREF, and soclose panics at this point.
*
* Here, we first take an extra reference to each inaccessible
* descriptor. Then, we call sorflush ourself, since we know
* it is a Unix domain socket anyhow. After we destroy all the
* rights carried in messages, we do a last closef to get rid
* of our extra reference. This is the last close, and the
* unp_detach etc will shut down the socket.
*
* 91/09/19, bsy@cs.cmu.edu
*/
extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK);
for (nunref = 0, fp = filehead.lh_first, fpp = extra_ref; fp != 0;
fp = nextfp) {
nextfp = fp->f_list.le_next;
if (fp->f_count == 0)
continue;
if (fp->f_count == fp->f_msgcount && !(fp->f_flag & FMARK)) {
*fpp++ = fp;
nunref++;
fp->f_count++;
}
}
for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp)
sorflush((struct socket *)(*fpp)->f_data);
for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp)
(void) closef(*fpp, (struct proc *)0);
free((caddr_t)extra_ref, M_FILE);
unp_gcing = 0;
}
void
unp_dispose(m)
struct mbuf *m;
{
if (m)
unp_scan(m, unp_discard);
}
void
unp_scan(m0, op)
register struct mbuf *m0;
void (*op) __P((struct file *));
{
register struct mbuf *m;
register struct file **rp;
register struct cmsghdr *cm;
register int i;
int qfds;
while (m0) {
for (m = m0; m; m = m->m_next)
if (m->m_type == MT_CONTROL &&
m->m_len >= sizeof(*cm)) {
cm = mtod(m, struct cmsghdr *);
if (cm->cmsg_level != SOL_SOCKET ||
cm->cmsg_type != SCM_RIGHTS)
continue;
qfds = (cm->cmsg_len - sizeof *cm)
/ sizeof (struct file *);
rp = (struct file **)(cm + 1);
for (i = 0; i < qfds; i++)
(*op)(*rp++);
break; /* XXX, but saves time */
}
m0 = m0->m_act;
}
}
void
unp_mark(fp)
struct file *fp;
{
if (fp->f_flag & FMARK)
return;
unp_defer++;
fp->f_flag |= (FMARK|FDEFER);
}
void
unp_discard(fp)
struct file *fp;
{
fp->f_msgcount--;
unp_rights--;
(void) closef(fp, (struct proc *)0);
}
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