qemu/slirp/udp.c
Petr Matousek 01f7cecf00 slirp: udp: fix NULL pointer dereference because of uninitialized socket
When guest sends udp packet with source port and source addr 0,
uninitialized socket is picked up when looking for matching and already
created udp sockets, and later passed to sosendto() where NULL pointer
dereference is hit during so->slirp->vnetwork_mask.s_addr access.

Fix this by checking that the socket is not just a socket stub.

This is CVE-2014-3640.

Signed-off-by: Petr Matousek <pmatouse@redhat.com>
Reported-by: Xavier Mehrenberger <xavier.mehrenberger@airbus.com>
Reported-by: Stephane Duverger <stephane.duverger@eads.net>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Message-id: 20140918063537.GX9321@dhcp-25-225.brq.redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-09-23 19:15:05 +01:00

395 lines
9.8 KiB
C

/*
* Copyright (c) 1982, 1986, 1988, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)udp_usrreq.c 8.4 (Berkeley) 1/21/94
* udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
*/
/*
* Changes and additions relating to SLiRP
* Copyright (c) 1995 Danny Gasparovski.
*
* Please read the file COPYRIGHT for the
* terms and conditions of the copyright.
*/
#include <slirp.h>
#include "ip_icmp.h"
static uint8_t udp_tos(struct socket *so);
void
udp_init(Slirp *slirp)
{
slirp->udb.so_next = slirp->udb.so_prev = &slirp->udb;
slirp->udp_last_so = &slirp->udb;
}
void udp_cleanup(Slirp *slirp)
{
while (slirp->udb.so_next != &slirp->udb) {
udp_detach(slirp->udb.so_next);
}
}
/* m->m_data points at ip packet header
* m->m_len length ip packet
* ip->ip_len length data (IPDU)
*/
void
udp_input(register struct mbuf *m, int iphlen)
{
Slirp *slirp = m->slirp;
register struct ip *ip;
register struct udphdr *uh;
int len;
struct ip save_ip;
struct socket *so;
DEBUG_CALL("udp_input");
DEBUG_ARG("m = %lx", (long)m);
DEBUG_ARG("iphlen = %d", iphlen);
/*
* Strip IP options, if any; should skip this,
* make available to user, and use on returned packets,
* but we don't yet have a way to check the checksum
* with options still present.
*/
if(iphlen > sizeof(struct ip)) {
ip_stripoptions(m, (struct mbuf *)0);
iphlen = sizeof(struct ip);
}
/*
* Get IP and UDP header together in first mbuf.
*/
ip = mtod(m, struct ip *);
uh = (struct udphdr *)((caddr_t)ip + iphlen);
/*
* Make mbuf data length reflect UDP length.
* If not enough data to reflect UDP length, drop.
*/
len = ntohs((uint16_t)uh->uh_ulen);
if (ip->ip_len != len) {
if (len > ip->ip_len) {
goto bad;
}
m_adj(m, len - ip->ip_len);
ip->ip_len = len;
}
/*
* Save a copy of the IP header in case we want restore it
* for sending an ICMP error message in response.
*/
save_ip = *ip;
save_ip.ip_len+= iphlen; /* tcp_input subtracts this */
/*
* Checksum extended UDP header and data.
*/
if (uh->uh_sum) {
memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
((struct ipovly *)ip)->ih_x1 = 0;
((struct ipovly *)ip)->ih_len = uh->uh_ulen;
if(cksum(m, len + sizeof(struct ip))) {
goto bad;
}
}
/*
* handle DHCP/BOOTP
*/
if (ntohs(uh->uh_dport) == BOOTP_SERVER &&
(ip->ip_dst.s_addr == slirp->vhost_addr.s_addr ||
ip->ip_dst.s_addr == 0xffffffff)) {
bootp_input(m);
goto bad;
}
/*
* handle TFTP
*/
if (ntohs(uh->uh_dport) == TFTP_SERVER &&
ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
tftp_input(m);
goto bad;
}
if (slirp->restricted) {
goto bad;
}
/*
* Locate pcb for datagram.
*/
so = slirp->udp_last_so;
if (so == &slirp->udb || so->so_lport != uh->uh_sport ||
so->so_laddr.s_addr != ip->ip_src.s_addr) {
struct socket *tmp;
for (tmp = slirp->udb.so_next; tmp != &slirp->udb;
tmp = tmp->so_next) {
if (tmp->so_lport == uh->uh_sport &&
tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
so = tmp;
break;
}
}
if (tmp == &slirp->udb) {
so = NULL;
} else {
slirp->udp_last_so = so;
}
}
if (so == NULL) {
/*
* If there's no socket for this packet,
* create one
*/
so = socreate(slirp);
if (!so) {
goto bad;
}
if(udp_attach(so) == -1) {
DEBUG_MISC((dfd," udp_attach errno = %d-%s\n",
errno,strerror(errno)));
sofree(so);
goto bad;
}
/*
* Setup fields
*/
so->so_laddr = ip->ip_src;
so->so_lport = uh->uh_sport;
if ((so->so_iptos = udp_tos(so)) == 0)
so->so_iptos = ip->ip_tos;
/*
* XXXXX Here, check if it's in udpexec_list,
* and if it is, do the fork_exec() etc.
*/
}
so->so_faddr = ip->ip_dst; /* XXX */
so->so_fport = uh->uh_dport; /* XXX */
iphlen += sizeof(struct udphdr);
m->m_len -= iphlen;
m->m_data += iphlen;
/*
* Now we sendto() the packet.
*/
if(sosendto(so,m) == -1) {
m->m_len += iphlen;
m->m_data -= iphlen;
*ip=save_ip;
DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
}
m_free(so->so_m); /* used for ICMP if error on sorecvfrom */
/* restore the orig mbuf packet */
m->m_len += iphlen;
m->m_data -= iphlen;
*ip=save_ip;
so->so_m=m; /* ICMP backup */
return;
bad:
m_free(m);
}
int udp_output2(struct socket *so, struct mbuf *m,
struct sockaddr_in *saddr, struct sockaddr_in *daddr,
int iptos)
{
register struct udpiphdr *ui;
int error = 0;
DEBUG_CALL("udp_output");
DEBUG_ARG("so = %lx", (long)so);
DEBUG_ARG("m = %lx", (long)m);
DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);
/*
* Adjust for header
*/
m->m_data -= sizeof(struct udpiphdr);
m->m_len += sizeof(struct udpiphdr);
/*
* Fill in mbuf with extended UDP header
* and addresses and length put into network format.
*/
ui = mtod(m, struct udpiphdr *);
memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
ui->ui_x1 = 0;
ui->ui_pr = IPPROTO_UDP;
ui->ui_len = htons(m->m_len - sizeof(struct ip));
/* XXXXX Check for from-one-location sockets, or from-any-location sockets */
ui->ui_src = saddr->sin_addr;
ui->ui_dst = daddr->sin_addr;
ui->ui_sport = saddr->sin_port;
ui->ui_dport = daddr->sin_port;
ui->ui_ulen = ui->ui_len;
/*
* Stuff checksum and output datagram.
*/
ui->ui_sum = 0;
if ((ui->ui_sum = cksum(m, m->m_len)) == 0)
ui->ui_sum = 0xffff;
((struct ip *)ui)->ip_len = m->m_len;
((struct ip *)ui)->ip_ttl = IPDEFTTL;
((struct ip *)ui)->ip_tos = iptos;
error = ip_output(so, m);
return (error);
}
int udp_output(struct socket *so, struct mbuf *m,
struct sockaddr_in *addr)
{
Slirp *slirp = so->slirp;
struct sockaddr_in saddr, daddr;
saddr = *addr;
if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
slirp->vnetwork_addr.s_addr) {
uint32_t inv_mask = ~slirp->vnetwork_mask.s_addr;
if ((so->so_faddr.s_addr & inv_mask) == inv_mask) {
saddr.sin_addr = slirp->vhost_addr;
} else if (addr->sin_addr.s_addr == loopback_addr.s_addr ||
so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
saddr.sin_addr = so->so_faddr;
}
}
daddr.sin_addr = so->so_laddr;
daddr.sin_port = so->so_lport;
return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
}
int
udp_attach(struct socket *so)
{
if((so->s = qemu_socket(AF_INET,SOCK_DGRAM,0)) != -1) {
so->so_expire = curtime + SO_EXPIRE;
insque(so, &so->slirp->udb);
}
return(so->s);
}
void
udp_detach(struct socket *so)
{
closesocket(so->s);
sofree(so);
}
static const struct tos_t udptos[] = {
{0, 53, IPTOS_LOWDELAY, 0}, /* DNS */
{0, 0, 0, 0}
};
static uint8_t
udp_tos(struct socket *so)
{
int i = 0;
while(udptos[i].tos) {
if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
(udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
so->so_emu = udptos[i].emu;
return udptos[i].tos;
}
i++;
}
return 0;
}
struct socket *
udp_listen(Slirp *slirp, uint32_t haddr, u_int hport, uint32_t laddr,
u_int lport, int flags)
{
struct sockaddr_in addr;
struct socket *so;
socklen_t addrlen = sizeof(struct sockaddr_in);
so = socreate(slirp);
if (!so) {
return NULL;
}
so->s = qemu_socket(AF_INET,SOCK_DGRAM,0);
so->so_expire = curtime + SO_EXPIRE;
insque(so, &slirp->udb);
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = haddr;
addr.sin_port = hport;
if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
udp_detach(so);
return NULL;
}
socket_set_fast_reuse(so->s);
getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
so->so_fport = addr.sin_port;
if (addr.sin_addr.s_addr == 0 ||
addr.sin_addr.s_addr == loopback_addr.s_addr) {
so->so_faddr = slirp->vhost_addr;
} else {
so->so_faddr = addr.sin_addr;
}
so->so_lport = lport;
so->so_laddr.s_addr = laddr;
if (flags != SS_FACCEPTONCE)
so->so_expire = 0;
so->so_state &= SS_PERSISTENT_MASK;
so->so_state |= SS_ISFCONNECTED | flags;
return so;
}