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freebsd-nq/sys/net/raw_usrreq.c
Robert Watson 81158452be Push acquisition of the accept mutex out of sofree() into the caller 
(sorele()/sotryfree()):

- This permits the caller to acquire the accept mutex before the socket
  mutex, avoiding sofree() having to drop the socket mutex and re-order,
  which could lead to races permitting more than one thread to enter
  sofree() after a socket is ready to be free'd.

- This also covers clearing of the so_pcb weak socket reference from
  the protocol to the socket, preventing races in clearing and
  evaluation of the reference such that sofree() might be called more
  than once on the same socket.

This appears to close a race I was able to easily trigger by repeatedly
opening and resetting TCP connections to a host, in which the
tcp_close() code called as a result of the RST raced with the close()
of the accepted socket in the user process resulting in simultaneous
attempts to de-allocate the same socket.  The new locking increases
the overhead for operations that may potentially free the socket, so we
will want to revise the synchronization strategy here as we normalize
the reference counting model for sockets.  The use of the accept mutex
in freeing of sockets that are not listen sockets is primarily
motivated by the potential need to remove the socket from the
incomplete connection queue on its parent (listen) socket, so cleaning
up the reference model here may allow us to substantially weaken the
synchronization requirements.

RELENG_5_3 candidate.

MFC after:	3 days
Reviewed by:	dwhite
Discussed with:	gnn, dwhite, green
Reported by:	Marc UBM Bocklet <ubm at u-boot-man dot de>
Reported by:	Vlad <marchenko at gmail dot com>
2004-10-18 22:19:43 +00:00

306 lines
6.6 KiB
C
Raw Blame History

/*
* Copyright (c) 1980, 1986, 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.
* 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.
*
* @(#)raw_usrreq.c 8.1 (Berkeley) 6/10/93
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/protosw.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/systm.h>
#include <net/raw_cb.h>
MTX_SYSINIT(rawcb_mtx, &rawcb_mtx, "rawcb", MTX_DEF);
/*
* Initialize raw connection block q.
*/
void
raw_init()
{
LIST_INIT(&rawcb_list);
}
/*
* Raw protocol input routine. Find the socket
* associated with the packet(s) and move them over. If
* nothing exists for this packet, drop it.
*/
/*
* Raw protocol interface.
*/
void
raw_input(m0, proto, src, dst)
struct mbuf *m0;
register struct sockproto *proto;
struct sockaddr *src, *dst;
{
register struct rawcb *rp;
register struct mbuf *m = m0;
struct socket *last;
last = 0;
mtx_lock(&rawcb_mtx);
LIST_FOREACH(rp, &rawcb_list, list) {
if (rp->rcb_proto.sp_family != proto->sp_family)
continue;
if (rp->rcb_proto.sp_protocol &&
rp->rcb_proto.sp_protocol != proto->sp_protocol)
continue;
/*
* We assume the lower level routines have
* placed the address in a canonical format
* suitable for a structure comparison.
*
* Note that if the lengths are not the same
* the comparison will fail at the first byte.
*/
#define equal(a1, a2) \
(bcmp((caddr_t)(a1), (caddr_t)(a2), a1->sa_len) == 0)
if (rp->rcb_laddr && !equal(rp->rcb_laddr, dst))
continue;
if (rp->rcb_faddr && !equal(rp->rcb_faddr, src))
continue;
if (last) {
struct mbuf *n;
n = m_copy(m, 0, (int)M_COPYALL);
if (n) {
if (sbappendaddr(&last->so_rcv, src,
n, (struct mbuf *)0) == 0)
/* should notify about lost packet */
m_freem(n);
else {
sorwakeup(last);
}
}
}
last = rp->rcb_socket;
}
if (last) {
if (sbappendaddr(&last->so_rcv, src,
m, (struct mbuf *)0) == 0)
m_freem(m);
else {
sorwakeup(last);
}
} else
m_freem(m);
mtx_unlock(&rawcb_mtx);
}
/*ARGSUSED*/
void
raw_ctlinput(cmd, arg, dummy)
int cmd;
struct sockaddr *arg;
void *dummy;
{
if (cmd < 0 || cmd >= PRC_NCMDS)
return;
/* INCOMPLETE */
}
static int
raw_uabort(struct socket *so)
{
struct rawcb *rp = sotorawcb(so);
if (rp == 0)
return EINVAL;
raw_disconnect(rp);
soisdisconnected(so);
ACCEPT_LOCK();
SOCK_LOCK(so);
sotryfree(so);
return 0;
}
/* pru_accept is EOPNOTSUPP */
static int
raw_uattach(struct socket *so, int proto, struct thread *td)
{
struct rawcb *rp = sotorawcb(so);
int error;
if (rp == 0)
return EINVAL;
if (td && (error = suser(td)) != 0)
return error;
return raw_attach(so, proto);
}
static int
raw_ubind(struct socket *so, struct sockaddr *nam, struct thread *td)
{
return EINVAL;
}
static int
raw_uconnect(struct socket *so, struct sockaddr *nam, struct thread *td)
{
return EINVAL;
}
/* pru_connect2 is EOPNOTSUPP */
/* pru_control is EOPNOTSUPP */
static int
raw_udetach(struct socket *so)
{
struct rawcb *rp = sotorawcb(so);
if (rp == 0)
return EINVAL;
raw_detach(rp);
return 0;
}
static int
raw_udisconnect(struct socket *so)
{
struct rawcb *rp = sotorawcb(so);
if (rp == 0)
return EINVAL;
if (rp->rcb_faddr == 0) {
return ENOTCONN;
}
raw_disconnect(rp);
soisdisconnected(so);
return 0;
}
/* pru_listen is EOPNOTSUPP */
static int
raw_upeeraddr(struct socket *so, struct sockaddr **nam)
{
struct rawcb *rp = sotorawcb(so);
if (rp == 0)
return EINVAL;
if (rp->rcb_faddr == 0) {
return ENOTCONN;
}
*nam = sodupsockaddr(rp->rcb_faddr, M_WAITOK);
return 0;
}
/* pru_rcvd is EOPNOTSUPP */
/* pru_rcvoob is EOPNOTSUPP */
static int
raw_usend(struct socket *so, int flags, struct mbuf *m,
struct sockaddr *nam, struct mbuf *control, struct thread *td)
{
int error;
struct rawcb *rp = sotorawcb(so);
if (rp == 0) {
error = EINVAL;
goto release;
}
if (flags & PRUS_OOB) {
error = EOPNOTSUPP;
goto release;
}
if (control && control->m_len) {
error = EOPNOTSUPP;
goto release;
}
if (nam) {
if (rp->rcb_faddr) {
error = EISCONN;
goto release;
}
rp->rcb_faddr = nam;
} else if (rp->rcb_faddr == 0) {
error = ENOTCONN;
goto release;
}
error = (*so->so_proto->pr_output)(m, so);
m = NULL;
if (nam)
rp->rcb_faddr = 0;
release:
if (m != NULL)
m_freem(m);
return (error);
}
/* pru_sense is null */
static int
raw_ushutdown(struct socket *so)
{
struct rawcb *rp = sotorawcb(so);
if (rp == 0)
return EINVAL;
socantsendmore(so);
return 0;
}
static int
raw_usockaddr(struct socket *so, struct sockaddr **nam)
{
struct rawcb *rp = sotorawcb(so);
if (rp == 0)
return EINVAL;
if (rp->rcb_laddr == 0)
return EINVAL;
*nam = sodupsockaddr(rp->rcb_laddr, M_WAITOK);
return 0;
}
struct pr_usrreqs raw_usrreqs = {
raw_uabort, pru_accept_notsupp, raw_uattach, raw_ubind, raw_uconnect,
pru_connect2_notsupp, pru_control_notsupp, raw_udetach,
raw_udisconnect, pru_listen_notsupp, raw_upeeraddr, pru_rcvd_notsupp,
pru_rcvoob_notsupp, raw_usend, pru_sense_null, raw_ushutdown,
raw_usockaddr, sosend, soreceive, sopoll, pru_sosetlabel_null
};
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