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freebsd-dev/sys/netatalk/ddp_pcb.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

378 lines
9.0 KiB
C
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/*
* Copyright (c) 2004 Robert N. M. Watson
* Copyright (c) 1990,1994 Regents of The University of Michigan.
* All Rights Reserved. See COPYRIGHT.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <net/if.h>
#include <net/route.h>
#include <net/netisr.h>
#include <netatalk/at.h>
#include <netatalk/at_var.h>
#include <netatalk/ddp_var.h>
#include <netatalk/ddp_pcb.h>
#include <netatalk/at_extern.h>
struct mtx ddp_list_mtx;
static struct ddpcb *ddp_ports[ ATPORT_LAST ];
struct ddpcb *ddpcb_list = NULL;
void
at_sockaddr(struct ddpcb *ddp, struct sockaddr **addr)
{
/*
* Prevent modification of ddp during copy of addr.
*/
DDP_LOCK_ASSERT(ddp);
*addr = sodupsockaddr((struct sockaddr *)&ddp->ddp_lsat, M_NOWAIT);
}
int
at_pcbsetaddr(struct ddpcb *ddp, struct sockaddr *addr, struct thread *td)
{
struct sockaddr_at lsat, *sat;
struct at_ifaddr *aa;
struct ddpcb *ddpp;
/*
* We read and write both the ddp passed in, and also ddp_ports.
*/
DDP_LIST_XLOCK_ASSERT();
DDP_LOCK_ASSERT(ddp);
if (ddp->ddp_lsat.sat_port != ATADDR_ANYPORT) { /* shouldn't be bound */
return (EINVAL);
}
if (addr != NULL) { /* validate passed address */
sat = (struct sockaddr_at *)addr;
if (sat->sat_family != AF_APPLETALK) {
return (EAFNOSUPPORT);
}
if (sat->sat_addr.s_node != ATADDR_ANYNODE ||
sat->sat_addr.s_net != ATADDR_ANYNET) {
for (aa = at_ifaddr_list; aa != NULL; aa = aa->aa_next) {
if ((sat->sat_addr.s_net == AA_SAT(aa)->sat_addr.s_net) &&
(sat->sat_addr.s_node == AA_SAT(aa)->sat_addr.s_node)) {
break;
}
}
if (!aa) {
return (EADDRNOTAVAIL);
}
}
if (sat->sat_port != ATADDR_ANYPORT) {
if (sat->sat_port < ATPORT_FIRST ||
sat->sat_port >= ATPORT_LAST) {
return (EINVAL);
}
if (sat->sat_port < ATPORT_RESERVED &&
suser(td)) {
return (EACCES);
}
}
} else {
bzero((caddr_t)&lsat, sizeof(struct sockaddr_at));
lsat.sat_len = sizeof(struct sockaddr_at);
lsat.sat_addr.s_node = ATADDR_ANYNODE;
lsat.sat_addr.s_net = ATADDR_ANYNET;
lsat.sat_family = AF_APPLETALK;
sat = &lsat;
}
if (sat->sat_addr.s_node == ATADDR_ANYNODE &&
sat->sat_addr.s_net == ATADDR_ANYNET) {
if (at_ifaddr_list == NULL) {
return (EADDRNOTAVAIL);
}
sat->sat_addr = AA_SAT(at_ifaddr_list)->sat_addr;
}
ddp->ddp_lsat = *sat;
/*
* Choose port.
*/
if (sat->sat_port == ATADDR_ANYPORT) {
for (sat->sat_port = ATPORT_RESERVED;
sat->sat_port < ATPORT_LAST; sat->sat_port++) {
if (ddp_ports[ sat->sat_port - 1 ] == NULL) {
break;
}
}
if (sat->sat_port == ATPORT_LAST) {
return (EADDRNOTAVAIL);
}
ddp->ddp_lsat.sat_port = sat->sat_port;
ddp_ports[ sat->sat_port - 1 ] = ddp;
} else {
for (ddpp = ddp_ports[ sat->sat_port - 1 ]; ddpp;
ddpp = ddpp->ddp_pnext) {
if (ddpp->ddp_lsat.sat_addr.s_net == sat->sat_addr.s_net &&
ddpp->ddp_lsat.sat_addr.s_node == sat->sat_addr.s_node) {
break;
}
}
if (ddpp != NULL) {
return (EADDRINUSE);
}
ddp->ddp_pnext = ddp_ports[ sat->sat_port - 1 ];
ddp_ports[ sat->sat_port - 1 ] = ddp;
if (ddp->ddp_pnext) {
ddp->ddp_pnext->ddp_pprev = ddp;
}
}
return (0);
}
int
at_pcbconnect(struct ddpcb *ddp, struct sockaddr *addr, struct thread *td)
{
struct sockaddr_at *sat = (struct sockaddr_at *)addr;
struct route *ro;
struct at_ifaddr *aa = NULL;
struct ifnet *ifp;
u_short hintnet = 0, net;
DDP_LIST_XLOCK_ASSERT();
DDP_LOCK_ASSERT(ddp);
if (sat->sat_family != AF_APPLETALK) {
return (EAFNOSUPPORT);
}
/*
* Under phase 2, network 0 means "the network". We take "the
* network" to mean the network the control block is bound to.
* If the control block is not bound, there is an error.
*/
if (sat->sat_addr.s_net == ATADDR_ANYNET
&& sat->sat_addr.s_node != ATADDR_ANYNODE) {
if (ddp->ddp_lsat.sat_port == ATADDR_ANYPORT) {
return (EADDRNOTAVAIL);
}
hintnet = ddp->ddp_lsat.sat_addr.s_net;
}
ro = &ddp->ddp_route;
/*
* If we've got an old route for this pcb, check that it is valid.
* If we've changed our address, we may have an old "good looking"
* route here. Attempt to detect it.
*/
if (ro->ro_rt) {
if (hintnet) {
net = hintnet;
} else {
net = sat->sat_addr.s_net;
}
aa = NULL;
if ((ifp = ro->ro_rt->rt_ifp) != NULL) {
for (aa = at_ifaddr_list; aa != NULL; aa = aa->aa_next) {
if (aa->aa_ifp == ifp &&
ntohs(net) >= ntohs(aa->aa_firstnet) &&
ntohs(net) <= ntohs(aa->aa_lastnet)) {
break;
}
}
}
if (aa == NULL || (satosat(&ro->ro_dst)->sat_addr.s_net !=
(hintnet ? hintnet : sat->sat_addr.s_net) ||
satosat(&ro->ro_dst)->sat_addr.s_node !=
sat->sat_addr.s_node)) {
RTFREE(ro->ro_rt);
ro->ro_rt = NULL;
}
}
/*
* If we've got no route for this interface, try to find one.
*/
if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp == NULL) {
ro->ro_dst.sa_len = sizeof(struct sockaddr_at);
ro->ro_dst.sa_family = AF_APPLETALK;
if (hintnet) {
satosat(&ro->ro_dst)->sat_addr.s_net = hintnet;
} else {
satosat(&ro->ro_dst)->sat_addr.s_net = sat->sat_addr.s_net;
}
satosat(&ro->ro_dst)->sat_addr.s_node = sat->sat_addr.s_node;
rtalloc(ro);
}
/*
* Make sure any route that we have has a valid interface.
*/
aa = NULL;
if (ro->ro_rt && (ifp = ro->ro_rt->rt_ifp)) {
for (aa = at_ifaddr_list; aa != NULL; aa = aa->aa_next) {
if (aa->aa_ifp == ifp) {
break;
}
}
}
if (aa == NULL) {
return (ENETUNREACH);
}
ddp->ddp_fsat = *sat;
if (ddp->ddp_lsat.sat_port == ATADDR_ANYPORT) {
return (at_pcbsetaddr(ddp, NULL, td));
}
return (0);
}
void
at_pcbdisconnect(struct ddpcb *ddp)
{
DDP_LOCK_ASSERT(ddp);
ddp->ddp_fsat.sat_addr.s_net = ATADDR_ANYNET;
ddp->ddp_fsat.sat_addr.s_node = ATADDR_ANYNODE;
ddp->ddp_fsat.sat_port = ATADDR_ANYPORT;
}
int
at_pcballoc(struct socket *so)
{
struct ddpcb *ddp;
DDP_LIST_XLOCK_ASSERT();
MALLOC(ddp, struct ddpcb *, sizeof *ddp, M_PCB, M_NOWAIT | M_ZERO);
DDP_LOCK_INIT(ddp);
ddp->ddp_lsat.sat_port = ATADDR_ANYPORT;
ddp->ddp_socket = so;
so->so_pcb = (caddr_t)ddp;
ddp->ddp_next = ddpcb_list;
ddp->ddp_prev = NULL;
ddp->ddp_pprev = NULL;
ddp->ddp_pnext = NULL;
if (ddpcb_list != NULL) {
ddpcb_list->ddp_prev = ddp;
}
ddpcb_list = ddp;
return(0);
}
void
at_pcbdetach(struct socket *so, struct ddpcb *ddp)
{
/*
* We modify ddp, ddp_ports, and the global list.
*/
DDP_LIST_XLOCK_ASSERT();
DDP_LOCK_ASSERT(ddp);
soisdisconnected(so);
ACCEPT_LOCK();
SOCK_LOCK(so);
so->so_pcb = NULL;
sotryfree(so);
/* remove ddp from ddp_ports list */
if (ddp->ddp_lsat.sat_port != ATADDR_ANYPORT &&
ddp_ports[ ddp->ddp_lsat.sat_port - 1 ] != NULL) {
if (ddp->ddp_pprev != NULL) {
ddp->ddp_pprev->ddp_pnext = ddp->ddp_pnext;
} else {
ddp_ports[ ddp->ddp_lsat.sat_port - 1 ] = ddp->ddp_pnext;
}
if (ddp->ddp_pnext != NULL) {
ddp->ddp_pnext->ddp_pprev = ddp->ddp_pprev;
}
}
if (ddp->ddp_route.ro_rt) {
RTFREE(ddp->ddp_route.ro_rt);
}
if (ddp->ddp_prev) {
ddp->ddp_prev->ddp_next = ddp->ddp_next;
} else {
ddpcb_list = ddp->ddp_next;
}
if (ddp->ddp_next) {
ddp->ddp_next->ddp_prev = ddp->ddp_prev;
}
DDP_UNLOCK(ddp);
DDP_LOCK_DESTROY(ddp);
FREE(ddp, M_PCB);
}
/*
* For the moment, this just find the pcb with the correct local address.
* In the future, this will actually do some real searching, so we can use
* the sender's address to do de-multiplexing on a single port to many
* sockets (pcbs).
*/
struct ddpcb *
ddp_search(struct sockaddr_at *from, struct sockaddr_at *to,
struct at_ifaddr *aa)
{
struct ddpcb *ddp;
DDP_LIST_SLOCK_ASSERT();
/*
* Check for bad ports.
*/
if (to->sat_port < ATPORT_FIRST || to->sat_port >= ATPORT_LAST) {
return (NULL);
}
/*
* Make sure the local address matches the sent address. What about
* the interface?
*/
for (ddp = ddp_ports[ to->sat_port - 1 ]; ddp; ddp = ddp->ddp_pnext) {
DDP_LOCK(ddp);
/* XXX should we handle 0.YY? */
/* XXXX.YY to socket on destination interface */
if (to->sat_addr.s_net == ddp->ddp_lsat.sat_addr.s_net &&
to->sat_addr.s_node == ddp->ddp_lsat.sat_addr.s_node) {
DDP_UNLOCK(ddp);
break;
}
/* 0.255 to socket on receiving interface */
if (to->sat_addr.s_node == ATADDR_BCAST && (to->sat_addr.s_net == 0 ||
to->sat_addr.s_net == ddp->ddp_lsat.sat_addr.s_net) &&
ddp->ddp_lsat.sat_addr.s_net == AA_SAT(aa)->sat_addr.s_net) {
DDP_UNLOCK(ddp);
break;
}
/* XXXX.0 to socket on destination interface */
if (to->sat_addr.s_net == aa->aa_firstnet &&
to->sat_addr.s_node == 0 &&
ntohs(ddp->ddp_lsat.sat_addr.s_net) >=
ntohs(aa->aa_firstnet) &&
ntohs(ddp->ddp_lsat.sat_addr.s_net) <=
ntohs(aa->aa_lastnet)) {
DDP_UNLOCK(ddp);
break;
}
DDP_UNLOCK(ddp);
}
return (ddp);
}
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