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freebsd-skq/sys/netinet/ip_input.c
julian 83b3321520 Submitted by: Archie cobbs (IPDIVERT author) 
close small security hole where an atacker could sendpackets with
IPDIVERT protocol, and select how it would be diverted thus bypassing
the ipfirewall.  Discovered by inspection rather than attack.
(you'd have to know how the firewall was configured (EXACTLY) to
make use of this but..)
1997-11-13 22:57:57 +00:00

1526 lines
37 KiB
C
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/*
* Copyright (c) 1982, 1986, 1988, 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.
*
* @(#)ip_input.c 8.2 (Berkeley) 1/4/94
* $Id: ip_input.c,v 1.71 1997/11/05 20:17:21 joerg Exp $
* $ANA: ip_input.c,v 1.5 1996/09/18 14:34:59 wollman Exp $
*/
#define _IP_VHL
#include "opt_ipfw.h"
#include "opt_ipdivert.h"
#include <stddef.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/netisr.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <machine/in_cksum.h>
#include <sys/socketvar.h>
#ifdef IPFIREWALL
#include <netinet/ip_fw.h>
#endif
int rsvp_on = 0;
static int ip_rsvp_on;
struct socket *ip_rsvpd;
static int ipforwarding = 0;
SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
&ipforwarding, 0, "");
static int ipsendredirects = 1; /* XXX */
SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
&ipsendredirects, 0, "");
int ip_defttl = IPDEFTTL;
SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
&ip_defttl, 0, "");
static int ip_dosourceroute = 0;
SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
&ip_dosourceroute, 0, "");
#ifdef DIAGNOSTIC
static int ipprintfs = 0;
#endif
extern struct domain inetdomain;
extern struct protosw inetsw[];
u_char ip_protox[IPPROTO_MAX];
static int ipqmaxlen = IFQ_MAXLEN;
struct in_ifaddrhead in_ifaddrhead; /* first inet address */
struct ifqueue ipintrq;
SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RD,
&ipintrq.ifq_maxlen, 0, "");
SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
&ipintrq.ifq_drops, 0, "");
struct ipstat ipstat;
SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RD,
&ipstat, ipstat, "");
/* Packet reassembly stuff */
#define IPREASS_NHASH_LOG2 6
#define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
#define IPREASS_HMASK (IPREASS_NHASH - 1)
#define IPREASS_HASH(x,y) \
((((x) & 0xF | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
static struct ipq ipq[IPREASS_NHASH];
static int nipq = 0; /* total # of reass queues */
static int maxnipq;
#ifdef IPCTL_DEFMTU
SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
&ip_mtu, 0, "");
#endif
#if !defined(COMPAT_IPFW) || COMPAT_IPFW == 1
#undef COMPAT_IPFW
#define COMPAT_IPFW 1
#else
#undef COMPAT_IPFW
#endif
#ifdef COMPAT_IPFW
/* Firewall hooks */
ip_fw_chk_t *ip_fw_chk_ptr;
ip_fw_ctl_t *ip_fw_ctl_ptr;
/* IP Network Address Translation (NAT) hooks */
ip_nat_t *ip_nat_ptr;
ip_nat_ctl_t *ip_nat_ctl_ptr;
#endif
#if defined(IPFILTER_LKM) || defined(IPFILTER)
int fr_check __P((struct ip *, int, struct ifnet *, int, struct mbuf **));
int (*fr_checkp) __P((struct ip *, int, struct ifnet *, int, struct mbuf **)) = NULL;
#endif
/*
* We need to save the IP options in case a protocol wants to respond
* to an incoming packet over the same route if the packet got here
* using IP source routing. This allows connection establishment and
* maintenance when the remote end is on a network that is not known
* to us.
*/
static int ip_nhops = 0;
static struct ip_srcrt {
struct in_addr dst; /* final destination */
char nop; /* one NOP to align */
char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
} ip_srcrt;
#ifdef IPDIVERT
/*
* Shared variable between ip_input() and ip_reass() to communicate
* about which packets, once assembled from fragments, get diverted,
* and to which port.
*/
static u_short frag_divert_port;
#endif
static void save_rte __P((u_char *, struct in_addr));
static void ip_deq __P((struct ipasfrag *));
static int ip_dooptions __P((struct mbuf *));
static void ip_enq __P((struct ipasfrag *, struct ipasfrag *));
static void ip_forward __P((struct mbuf *, int));
static void ip_freef __P((struct ipq *));
static struct ip *
ip_reass __P((struct ipasfrag *, struct ipq *, struct ipq *));
static struct in_ifaddr *
ip_rtaddr __P((struct in_addr));
static void ipintr __P((void));
/*
* IP initialization: fill in IP protocol switch table.
* All protocols not implemented in kernel go to raw IP protocol handler.
*/
void
ip_init()
{
register struct protosw *pr;
register int i;
TAILQ_INIT(&in_ifaddrhead);
pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
if (pr == 0)
panic("ip_init");
for (i = 0; i < IPPROTO_MAX; i++)
ip_protox[i] = pr - inetsw;
for (pr = inetdomain.dom_protosw;
pr < inetdomain.dom_protoswNPROTOSW; pr++)
if (pr->pr_domain->dom_family == PF_INET &&
pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
ip_protox[pr->pr_protocol] = pr - inetsw;
for (i = 0; i < IPREASS_NHASH; i++)
ipq[i].next = ipq[i].prev = &ipq[i];
maxnipq = nmbclusters/4;
ip_id = time.tv_sec & 0xffff;
ipintrq.ifq_maxlen = ipqmaxlen;
#ifdef IPFIREWALL
ip_fw_init();
#endif
#ifdef IPNAT
ip_nat_init();
#endif
}
static struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
static struct route ipforward_rt;
/*
* Ip input routine. Checksum and byte swap header. If fragmented
* try to reassemble. Process options. Pass to next level.
*/
void
ip_input(struct mbuf *m)
{
struct ip *ip;
struct ipq *fp;
struct in_ifaddr *ia;
int i, hlen;
u_short sum;
#ifdef DIAGNOSTIC
if ((m->m_flags & M_PKTHDR) == 0)
panic("ip_input no HDR");
#endif
/*
* If no IP addresses have been set yet but the interfaces
* are receiving, can't do anything with incoming packets yet.
* XXX This is broken! We should be able to receive broadcasts
* and multicasts even without any local addresses configured.
*/
if (TAILQ_EMPTY(&in_ifaddrhead))
goto bad;
ipstat.ips_total++;
if (m->m_pkthdr.len < sizeof(struct ip))
goto tooshort;
#ifdef DIAGNOSTIC
if (m->m_len < sizeof(struct ip))
panic("ipintr mbuf too short");
#endif
if (m->m_len < sizeof (struct ip) &&
(m = m_pullup(m, sizeof (struct ip))) == 0) {
ipstat.ips_toosmall++;
return;
}
ip = mtod(m, struct ip *);
if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
ipstat.ips_badvers++;
goto bad;
}
hlen = IP_VHL_HL(ip->ip_vhl) << 2;
if (hlen < sizeof(struct ip)) { /* minimum header length */
ipstat.ips_badhlen++;
goto bad;
}
if (hlen > m->m_len) {
if ((m = m_pullup(m, hlen)) == 0) {
ipstat.ips_badhlen++;
return;
}
ip = mtod(m, struct ip *);
}
if (hlen == sizeof(struct ip)) {
sum = in_cksum_hdr(ip);
} else {
sum = in_cksum(m, hlen);
}
if (sum) {
ipstat.ips_badsum++;
goto bad;
}
/*
* Convert fields to host representation.
*/
NTOHS(ip->ip_len);
if (ip->ip_len < hlen) {
ipstat.ips_badlen++;
goto bad;
}
NTOHS(ip->ip_id);
NTOHS(ip->ip_off);
/*
* Check that the amount of data in the buffers
* is as at least much as the IP header would have us expect.
* Trim mbufs if longer than we expect.
* Drop packet if shorter than we expect.
*/
if (m->m_pkthdr.len < ip->ip_len) {
tooshort:
ipstat.ips_tooshort++;
goto bad;
}
if (m->m_pkthdr.len > ip->ip_len) {
if (m->m_len == m->m_pkthdr.len) {
m->m_len = ip->ip_len;
m->m_pkthdr.len = ip->ip_len;
} else
m_adj(m, ip->ip_len - m->m_pkthdr.len);
}
/*
* IpHack's section.
* Right now when no processing on packet has done
* and it is still fresh out of network we do our black
* deals with it.
* - Firewall: deny/allow/divert
* - Xlate: translate packet's addr/port (NAT).
* - Wrap: fake packet's addr/port <unimpl.>
* - Encapsulate: put it in another IP and send out. <unimp.>
*/
#if defined(IPFILTER) || defined(IPFILTER_LKM)
/*
* Check if we want to allow this packet to be processed.
* Consider it to be bad if not.
*/
if (fr_check) {
struct mbuf *m1 = m;
if ((*fr_checkp)(ip, hlen, m->m_pkthdr.rcvif, 0, &m1) || !m1)
return;
ip = mtod(m = m1, struct ip *);
}
#endif
#ifdef COMPAT_IPFW
if (ip_fw_chk_ptr) {
#ifdef IPDIVERT
u_short port;
port = (*ip_fw_chk_ptr)(&ip, hlen, NULL, ip_divert_ignore, &m);
ip_divert_ignore = 0;
if (port) { /* Divert packet */
frag_divert_port = port;
goto ours;
}
#else
/* If ipfw says divert, we have to just drop packet */
if ((*ip_fw_chk_ptr)(&ip, hlen, NULL, 0, &m)) {
m_freem(m);
m = NULL;
}
#endif
if (!m)
return;
}
if (ip_nat_ptr && !(*ip_nat_ptr)(&ip, &m, m->m_pkthdr.rcvif, IP_NAT_IN))
return;
#endif
/*
* Process options and, if not destined for us,
* ship it on. ip_dooptions returns 1 when an
* error was detected (causing an icmp message
* to be sent and the original packet to be freed).
*/
ip_nhops = 0; /* for source routed packets */
if (hlen > sizeof (struct ip) && ip_dooptions(m))
return;
/* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
* matter if it is destined to another node, or whether it is
* a multicast one, RSVP wants it! and prevents it from being forwarded
* anywhere else. Also checks if the rsvp daemon is running before
* grabbing the packet.
*/
if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
goto ours;
/*
* Check our list of addresses, to see if the packet is for us.
*/
for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
#define satosin(sa) ((struct sockaddr_in *)(sa))
if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
goto ours;
#ifdef BOOTP_COMPAT
if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
goto ours;
#endif
if (ia->ia_ifp && ia->ia_ifp->if_flags & IFF_BROADCAST) {
if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
ip->ip_dst.s_addr)
goto ours;
if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
goto ours;
}
}
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
struct in_multi *inm;
if (ip_mrouter) {
/*
* If we are acting as a multicast router, all
* incoming multicast packets are passed to the
* kernel-level multicast forwarding function.
* The packet is returned (relatively) intact; if
* ip_mforward() returns a non-zero value, the packet
* must be discarded, else it may be accepted below.
*
* (The IP ident field is put in the same byte order
* as expected when ip_mforward() is called from
* ip_output().)
*/
ip->ip_id = htons(ip->ip_id);
if (ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
ipstat.ips_cantforward++;
m_freem(m);
return;
}
ip->ip_id = ntohs(ip->ip_id);
/*
* The process-level routing demon needs to receive
* all multicast IGMP packets, whether or not this
* host belongs to their destination groups.
*/
if (ip->ip_p == IPPROTO_IGMP)
goto ours;
ipstat.ips_forward++;
}
/*
* See if we belong to the destination multicast group on the
* arrival interface.
*/
IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
if (inm == NULL) {
ipstat.ips_notmember++;
m_freem(m);
return;
}
goto ours;
}
if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
goto ours;
if (ip->ip_dst.s_addr == INADDR_ANY)
goto ours;
/*
* Not for us; forward if possible and desirable.
*/
if (ipforwarding == 0) {
ipstat.ips_cantforward++;
m_freem(m);
} else
ip_forward(m, 0);
return;
ours:
/*
* If offset or IP_MF are set, must reassemble.
* Otherwise, nothing need be done.
* (We could look in the reassembly queue to see
* if the packet was previously fragmented,
* but it's not worth the time; just let them time out.)
*/
if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
if (m->m_flags & M_EXT) { /* XXX */
if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
ipstat.ips_toosmall++;
#ifdef IPDIVERT
frag_divert_port = 0;
#endif
return;
}
ip = mtod(m, struct ip *);
}
sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
/*
* Look for queue of fragments
* of this datagram.
*/
for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next)
if (ip->ip_id == fp->ipq_id &&
ip->ip_src.s_addr == fp->ipq_src.s_addr &&
ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
ip->ip_p == fp->ipq_p)
goto found;
fp = 0;
/* check if there's a place for the new queue */
if (nipq > maxnipq) {
/*
* drop something from the tail of the current queue
* before proceeding further
*/
if (ipq[sum].prev == &ipq[sum]) { /* gak */
for (i = 0; i < IPREASS_NHASH; i++) {
if (ipq[i].prev != &ipq[i]) {
ip_freef(ipq[i].prev);
break;
}
}
} else
ip_freef(ipq[sum].prev);
}
found:
/*
* Adjust ip_len to not reflect header,
* set ip_mff if more fragments are expected,
* convert offset of this to bytes.
*/
ip->ip_len -= hlen;
((struct ipasfrag *)ip)->ipf_mff &= ~1;
if (ip->ip_off & IP_MF)
((struct ipasfrag *)ip)->ipf_mff |= 1;
ip->ip_off <<= 3;
/*
* If datagram marked as having more fragments
* or if this is not the first fragment,
* attempt reassembly; if it succeeds, proceed.
*/
if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) {
ipstat.ips_fragments++;
ip = ip_reass((struct ipasfrag *)ip, fp, &ipq[sum]);
if (ip == 0)
return;
ipstat.ips_reassembled++;
m = dtom(ip);
#ifdef IPDIVERT
if (frag_divert_port) {
ip->ip_len += hlen;
HTONS(ip->ip_len);
HTONS(ip->ip_off);
HTONS(ip->ip_id);
ip->ip_sum = 0;
ip->ip_sum = in_cksum_hdr(ip);
NTOHS(ip->ip_id);
NTOHS(ip->ip_off);
NTOHS(ip->ip_len);
ip->ip_len -= hlen;
}
#endif
} else
if (fp)
ip_freef(fp);
} else
ip->ip_len -= hlen;
#ifdef IPDIVERT
/*
* Divert reassembled packets to the divert protocol if required
*/
if (frag_divert_port) {
ipstat.ips_delivered++;
ip_divert_port = frag_divert_port;
frag_divert_port = 0;
(*inetsw[ip_protox[IPPROTO_DIVERT]].pr_input)(m, hlen);
return;
}
/* Don't let packets divert themselves */
if (ip->ip_p == IPPROTO_DIVERT) {
ipstat.ips_noproto++;
goto bad;
}
#endif
/*
* Switch out to protocol's input routine.
*/
ipstat.ips_delivered++;
(*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
return;
bad:
m_freem(m);
}
/*
* IP software interrupt routine - to go away sometime soon
*/
static void
ipintr(void)
{
int s;
struct mbuf *m;
while(1) {
s = splimp();
IF_DEQUEUE(&ipintrq, m);
splx(s);
if (m == 0)
return;
ip_input(m);
}
}
NETISR_SET(NETISR_IP, ipintr);
/*
* Take incoming datagram fragment and try to
* reassemble it into whole datagram. If a chain for
* reassembly of this datagram already exists, then it
* is given as fp; otherwise have to make a chain.
*/
static struct ip *
ip_reass(ip, fp, where)
register struct ipasfrag *ip;
register struct ipq *fp;
struct ipq *where;
{
register struct mbuf *m = dtom(ip);
register struct ipasfrag *q;
struct mbuf *t;
int hlen = ip->ip_hl << 2;
int i, next;
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
m->m_data += hlen;
m->m_len -= hlen;
/*
* If first fragment to arrive, create a reassembly queue.
*/
if (fp == 0) {
if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
goto dropfrag;
fp = mtod(t, struct ipq *);
insque(fp, where);
nipq++;
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
fp->ipq_src = ((struct ip *)ip)->ip_src;
fp->ipq_dst = ((struct ip *)ip)->ip_dst;
#ifdef IPDIVERT
fp->ipq_divert = 0;
#endif
q = (struct ipasfrag *)fp;
goto insert;
}
/*
* Find a segment which begins after this one does.
*/
for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
if (q->ip_off > ip->ip_off)
break;
/*
* If there is a preceding segment, it may provide some of
* our data already. If so, drop the data from the incoming
* segment. If it provides all of our data, drop us.
*/
if (q->ipf_prev != (struct ipasfrag *)fp) {
i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
if (i > 0) {
if (i >= ip->ip_len)
goto dropfrag;
m_adj(dtom(ip), i);
ip->ip_off += i;
ip->ip_len -= i;
}
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
struct mbuf *m0;
i = (ip->ip_off + ip->ip_len) - q->ip_off;
if (i < q->ip_len) {
q->ip_len -= i;
q->ip_off += i;
m_adj(dtom(q), i);
break;
}
m0 = dtom(q);
q = q->ipf_next;
ip_deq(q->ipf_prev);
m_freem(m0);
}
insert:
#ifdef IPDIVERT
/*
* Any fragment diverting causes the whole packet to divert
*/
if (frag_divert_port != 0)
fp->ipq_divert = frag_divert_port;
frag_divert_port = 0;
#endif
/*
* Stick new segment in its place;
* check for complete reassembly.
*/
ip_enq(ip, q->ipf_prev);
next = 0;
for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
if (q->ip_off != next)
return (0);
next += q->ip_len;
}
if (q->ipf_prev->ipf_mff & 1)
return (0);
/*
* Reassembly is complete. Make sure the packet is a sane size.
*/
if (next + (IP_VHL_HL(((struct ip *)fp->ipq_next)->ip_vhl) << 2)
> IP_MAXPACKET) {
ipstat.ips_toolong++;
ip_freef(fp);
return (0);
}
/*
* Concatenate fragments.
*/
q = fp->ipq_next;
m = dtom(q);
t = m->m_next;
m->m_next = 0;
m_cat(m, t);
q = q->ipf_next;
while (q != (struct ipasfrag *)fp) {
t = dtom(q);
q = q->ipf_next;
m_cat(m, t);
}
#ifdef IPDIVERT
/*
* Record divert port for packet, if any
*/
frag_divert_port = fp->ipq_divert;
#endif
/*
* Create header for new ip packet by
* modifying header of first packet;
* dequeue and discard fragment reassembly header.
* Make header visible.
*/
ip = fp->ipq_next;
ip->ip_len = next;
ip->ipf_mff &= ~1;
((struct ip *)ip)->ip_src = fp->ipq_src;
((struct ip *)ip)->ip_dst = fp->ipq_dst;
remque(fp);
nipq--;
(void) m_free(dtom(fp));
m = dtom(ip);
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
/* some debugging cruft by sklower, below, will go away soon */
if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
register int plen = 0;
for (t = m; m; m = m->m_next)
plen += m->m_len;
t->m_pkthdr.len = plen;
}
return ((struct ip *)ip);
dropfrag:
ipstat.ips_fragdropped++;
m_freem(m);
return (0);
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static void
ip_freef(fp)
struct ipq *fp;
{
register struct ipasfrag *q, *p;
for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
p = q->ipf_next;
ip_deq(q);
m_freem(dtom(q));
}
remque(fp);
(void) m_free(dtom(fp));
nipq--;
}
/*
* Put an ip fragment on a reassembly chain.
* Like insque, but pointers in middle of structure.
*/
static void
ip_enq(p, prev)
register struct ipasfrag *p, *prev;
{
p->ipf_prev = prev;
p->ipf_next = prev->ipf_next;
prev->ipf_next->ipf_prev = p;
prev->ipf_next = p;
}
/*
* To ip_enq as remque is to insque.
*/
static void
ip_deq(p)
register struct ipasfrag *p;
{
p->ipf_prev->ipf_next = p->ipf_next;
p->ipf_next->ipf_prev = p->ipf_prev;
}
/*
* IP timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
ip_slowtimo()
{
register struct ipq *fp;
int s = splnet();
int i;
for (i = 0; i < IPREASS_NHASH; i++) {
fp = ipq[i].next;
if (fp == 0)
continue;
while (fp != &ipq[i]) {
--fp->ipq_ttl;
fp = fp->next;
if (fp->prev->ipq_ttl == 0) {
ipstat.ips_fragtimeout++;
ip_freef(fp->prev);
}
}
}
splx(s);
}
/*
* Drain off all datagram fragments.
*/
void
ip_drain()
{
int i;
for (i = 0; i < IPREASS_NHASH; i++) {
while (ipq[i].next != &ipq[i]) {
ipstat.ips_fragdropped++;
ip_freef(ipq[i].next);
}
}
in_rtqdrain();
}
/*
* Do option processing on a datagram,
* possibly discarding it if bad options are encountered,
* or forwarding it if source-routed.
* Returns 1 if packet has been forwarded/freed,
* 0 if the packet should be processed further.
*/
static int
ip_dooptions(m)
struct mbuf *m;
{
register struct ip *ip = mtod(m, struct ip *);
register u_char *cp;
register struct ip_timestamp *ipt;
register struct in_ifaddr *ia;
int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
struct in_addr *sin, dst;
n_time ntime;
dst = ip->ip_dst;
cp = (u_char *)(ip + 1);
cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[IPOPT_OPTVAL];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
optlen = 1;
else {
optlen = cp[IPOPT_OLEN];
if (optlen <= 0 || optlen > cnt) {
code = &cp[IPOPT_OLEN] - (u_char *)ip;
goto bad;
}
}
switch (opt) {
default:
break;
/*
* Source routing with record.
* Find interface with current destination address.
* If none on this machine then drop if strictly routed,
* or do nothing if loosely routed.
* Record interface address and bring up next address
* component. If strictly routed make sure next
* address is on directly accessible net.
*/
case IPOPT_LSRR:
case IPOPT_SSRR:
if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
ipaddr.sin_addr = ip->ip_dst;
ia = (struct in_ifaddr *)
ifa_ifwithaddr((struct sockaddr *)&ipaddr);
if (ia == 0) {
if (opt == IPOPT_SSRR) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_SRCFAIL;
goto bad;
}
if (!ip_dosourceroute)
goto nosourcerouting;
/*
* Loose routing, and not at next destination
* yet; nothing to do except forward.
*/
break;
}
off--; /* 0 origin */
if (off > optlen - sizeof(struct in_addr)) {
/*
* End of source route. Should be for us.
*/
save_rte(cp, ip->ip_src);
break;
}
if (!ip_dosourceroute) {
char buf[4*sizeof "123"];
nosourcerouting:
strcpy(buf, inet_ntoa(ip->ip_dst));
log(LOG_WARNING,
"attempted source route from %s to %s\n",
inet_ntoa(ip->ip_src), buf);
type = ICMP_UNREACH;
code = ICMP_UNREACH_SRCFAIL;
goto bad;
}
/*
* locate outgoing interface
*/
(void)memcpy(&ipaddr.sin_addr, cp + off,
sizeof(ipaddr.sin_addr));
if (opt == IPOPT_SSRR) {
#define INA struct in_ifaddr *
#define SA struct sockaddr *
if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
ia = (INA)ifa_ifwithnet((SA)&ipaddr);
} else
ia = ip_rtaddr(ipaddr.sin_addr);
if (ia == 0) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_SRCFAIL;
goto bad;
}
ip->ip_dst = ipaddr.sin_addr;
(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
sizeof(struct in_addr));
cp[IPOPT_OFFSET] += sizeof(struct in_addr);
/*
* Let ip_intr's mcast routing check handle mcast pkts
*/
forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
break;
case IPOPT_RR:
if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
/*
* If no space remains, ignore.
*/
off--; /* 0 origin */
if (off > optlen - sizeof(struct in_addr))
break;
(void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
sizeof(ipaddr.sin_addr));
/*
* locate outgoing interface; if we're the destination,
* use the incoming interface (should be same).
*/
if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
(ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_HOST;
goto bad;
}
(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
sizeof(struct in_addr));
cp[IPOPT_OFFSET] += sizeof(struct in_addr);
break;
case IPOPT_TS:
code = cp - (u_char *)ip;
ipt = (struct ip_timestamp *)cp;
if (ipt->ipt_len < 5)
goto bad;
if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
if (++ipt->ipt_oflw == 0)
goto bad;
break;
}
sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
switch (ipt->ipt_flg) {
case IPOPT_TS_TSONLY:
break;
case IPOPT_TS_TSANDADDR:
if (ipt->ipt_ptr + sizeof(n_time) +
sizeof(struct in_addr) > ipt->ipt_len)
goto bad;
ipaddr.sin_addr = dst;
ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
m->m_pkthdr.rcvif);
if (ia == 0)
continue;
(void)memcpy(sin, &IA_SIN(ia)->sin_addr,
sizeof(struct in_addr));
ipt->ipt_ptr += sizeof(struct in_addr);
break;
case IPOPT_TS_PRESPEC:
if (ipt->ipt_ptr + sizeof(n_time) +
sizeof(struct in_addr) > ipt->ipt_len)
goto bad;
(void)memcpy(&ipaddr.sin_addr, sin,
sizeof(struct in_addr));
if (ifa_ifwithaddr((SA)&ipaddr) == 0)
continue;
ipt->ipt_ptr += sizeof(struct in_addr);
break;
default:
goto bad;
}
ntime = iptime();
(void)memcpy(cp + ipt->ipt_ptr - 1, &ntime,
sizeof(n_time));
ipt->ipt_ptr += sizeof(n_time);
}
}
if (forward) {
ip_forward(m, 1);
return (1);
}
return (0);
bad:
ip->ip_len -= IP_VHL_HL(ip->ip_vhl) << 2; /* XXX icmp_error adds in hdr length */
icmp_error(m, type, code, 0, 0);
ipstat.ips_badoptions++;
return (1);
}
/*
* Given address of next destination (final or next hop),
* return internet address info of interface to be used to get there.
*/
static struct in_ifaddr *
ip_rtaddr(dst)
struct in_addr dst;
{
register struct sockaddr_in *sin;
sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
if (ipforward_rt.ro_rt) {
RTFREE(ipforward_rt.ro_rt);
ipforward_rt.ro_rt = 0;
}
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = dst;
rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
}
if (ipforward_rt.ro_rt == 0)
return ((struct in_ifaddr *)0);
return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
}
/*
* Save incoming source route for use in replies,
* to be picked up later by ip_srcroute if the receiver is interested.
*/
void
save_rte(option, dst)
u_char *option;
struct in_addr dst;
{
unsigned olen;
olen = option[IPOPT_OLEN];
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("save_rte: olen %d\n", olen);
#endif
if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
return;
bcopy(option, ip_srcrt.srcopt, olen);
ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
ip_srcrt.dst = dst;
}
/*
* Retrieve incoming source route for use in replies,
* in the same form used by setsockopt.
* The first hop is placed before the options, will be removed later.
*/
struct mbuf *
ip_srcroute()
{
register struct in_addr *p, *q;
register struct mbuf *m;
if (ip_nhops == 0)
return ((struct mbuf *)0);
m = m_get(M_DONTWAIT, MT_SOOPTS);
if (m == 0)
return ((struct mbuf *)0);
#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
OPTSIZ;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
#endif
/*
* First save first hop for return route
*/
p = &ip_srcrt.route[ip_nhops - 1];
*(mtod(m, struct in_addr *)) = *p--;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
#endif
/*
* Copy option fields and padding (nop) to mbuf.
*/
ip_srcrt.nop = IPOPT_NOP;
ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
(void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
&ip_srcrt.nop, OPTSIZ);
q = (struct in_addr *)(mtod(m, caddr_t) +
sizeof(struct in_addr) + OPTSIZ);
#undef OPTSIZ
/*
* Record return path as an IP source route,
* reversing the path (pointers are now aligned).
*/
while (p >= ip_srcrt.route) {
#ifdef DIAGNOSTIC
if (ipprintfs)
printf(" %lx", ntohl(q->s_addr));
#endif
*q++ = *p--;
}
/*
* Last hop goes to final destination.
*/
*q = ip_srcrt.dst;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf(" %lx\n", ntohl(q->s_addr));
#endif
return (m);
}
/*
* Strip out IP options, at higher
* level protocol in the kernel.
* Second argument is buffer to which options
* will be moved, and return value is their length.
* XXX should be deleted; last arg currently ignored.
*/
void
ip_stripoptions(m, mopt)
register struct mbuf *m;
struct mbuf *mopt;
{
register int i;
struct ip *ip = mtod(m, struct ip *);
register caddr_t opts;
int olen;
olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
opts = (caddr_t)(ip + 1);
i = m->m_len - (sizeof (struct ip) + olen);
bcopy(opts + olen, opts, (unsigned)i);
m->m_len -= olen;
if (m->m_flags & M_PKTHDR)
m->m_pkthdr.len -= olen;
ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
}
u_char inetctlerrmap[PRC_NCMDS] = {
0, 0, 0, 0,
0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
EMSGSIZE, EHOSTUNREACH, 0, 0,
0, 0, 0, 0,
ENOPROTOOPT
};
/*
* Forward a packet. If some error occurs return the sender
* an icmp packet. Note we can't always generate a meaningful
* icmp message because icmp doesn't have a large enough repertoire
* of codes and types.
*
* If not forwarding, just drop the packet. This could be confusing
* if ipforwarding was zero but some routing protocol was advancing
* us as a gateway to somewhere. However, we must let the routing
* protocol deal with that.
*
* The srcrt parameter indicates whether the packet is being forwarded
* via a source route.
*/
static void
ip_forward(m, srcrt)
struct mbuf *m;
int srcrt;
{
register struct ip *ip = mtod(m, struct ip *);
register struct sockaddr_in *sin;
register struct rtentry *rt;
int error, type = 0, code = 0;
struct mbuf *mcopy;
n_long dest;
struct ifnet *destifp;
dest = 0;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("forward: src %lx dst %lx ttl %x\n",
ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl);
#endif
if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
ipstat.ips_cantforward++;
m_freem(m);
return;
}
HTONS(ip->ip_id);
if (ip->ip_ttl <= IPTTLDEC) {
icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
return;
}
ip->ip_ttl -= IPTTLDEC;
sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
if ((rt = ipforward_rt.ro_rt) == 0 ||
ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
if (ipforward_rt.ro_rt) {
RTFREE(ipforward_rt.ro_rt);
ipforward_rt.ro_rt = 0;
}
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = ip->ip_dst;
rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
if (ipforward_rt.ro_rt == 0) {
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
return;
}
rt = ipforward_rt.ro_rt;
}
/*
* Save at most 64 bytes of the packet in case
* we need to generate an ICMP message to the src.
*/
mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
/*
* If forwarding packet using same interface that it came in on,
* perhaps should send a redirect to sender to shortcut a hop.
* Only send redirect if source is sending directly to us,
* and if packet was not source routed (or has any options).
* Also, don't send redirect if forwarding using a default route
* or a route modified by a redirect.
*/
#define satosin(sa) ((struct sockaddr_in *)(sa))
if (rt->rt_ifp == m->m_pkthdr.rcvif &&
(rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
ipsendredirects && !srcrt) {
#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
u_long src = ntohl(ip->ip_src.s_addr);
if (RTA(rt) &&
(src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
if (rt->rt_flags & RTF_GATEWAY)
dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
else
dest = ip->ip_dst.s_addr;
/* Router requirements says to only send host redirects */
type = ICMP_REDIRECT;
code = ICMP_REDIRECT_HOST;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("redirect (%d) to %lx\n", code, (u_long)dest);
#endif
}
}
error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
IP_FORWARDING, 0);
if (error)
ipstat.ips_cantforward++;
else {
ipstat.ips_forward++;
if (type)
ipstat.ips_redirectsent++;
else {
if (mcopy)
m_freem(mcopy);
return;
}
}
if (mcopy == NULL)
return;
destifp = NULL;
switch (error) {
case 0: /* forwarded, but need redirect */
/* type, code set above */
break;
case ENETUNREACH: /* shouldn't happen, checked above */
case EHOSTUNREACH:
case ENETDOWN:
case EHOSTDOWN:
default:
type = ICMP_UNREACH;
code = ICMP_UNREACH_HOST;
break;
case EMSGSIZE:
type = ICMP_UNREACH;
code = ICMP_UNREACH_NEEDFRAG;
if (ipforward_rt.ro_rt)
destifp = ipforward_rt.ro_rt->rt_ifp;
ipstat.ips_cantfrag++;
break;
case ENOBUFS:
type = ICMP_SOURCEQUENCH;
code = 0;
break;
}
icmp_error(mcopy, type, code, dest, destifp);
}
void
ip_savecontrol(inp, mp, ip, m)
register struct inpcb *inp;
register struct mbuf **mp;
register struct ip *ip;
register struct mbuf *m;
{
if (inp->inp_socket->so_options & SO_TIMESTAMP) {
struct timeval tv;
microtime(&tv);
*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
SCM_TIMESTAMP, SOL_SOCKET);
if (*mp)
mp = &(*mp)->m_next;
}
if (inp->inp_flags & INP_RECVDSTADDR) {
*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
#ifdef notyet
/* XXX
* Moving these out of udp_input() made them even more broken
* than they already were.
*/
/* options were tossed already */
if (inp->inp_flags & INP_RECVOPTS) {
*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
/* ip_srcroute doesn't do what we want here, need to fix */
if (inp->inp_flags & INP_RECVRETOPTS) {
*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
#endif
if (inp->inp_flags & INP_RECVIF) {
struct ifnet *ifp;
struct sdlbuf {
struct sockaddr_dl sdl;
u_char pad[32];
} sdlbuf;
struct sockaddr_dl *sdp;
struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
if (((ifp = m->m_pkthdr.rcvif))
&& ( ifp->if_index && (ifp->if_index <= if_index))) {
sdp = (struct sockaddr_dl *)(ifnet_addrs
[ifp->if_index - 1]->ifa_addr);
/*
* Change our mind and don't try copy.
*/
if ((sdp->sdl_family != AF_LINK)
|| (sdp->sdl_len > sizeof(sdlbuf))) {
goto makedummy;
}
bcopy(sdp, sdl2, sdp->sdl_len);
} else {
makedummy:
sdl2->sdl_len
= offsetof(struct sockaddr_dl, sdl_data[0]);
sdl2->sdl_family = AF_LINK;
sdl2->sdl_index = 0;
sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
}
*mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
IP_RECVIF, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
}
int
ip_rsvp_init(struct socket *so)
{
if (so->so_type != SOCK_RAW ||
so->so_proto->pr_protocol != IPPROTO_RSVP)
return EOPNOTSUPP;
if (ip_rsvpd != NULL)
return EADDRINUSE;
ip_rsvpd = so;
/*
* This may seem silly, but we need to be sure we don't over-increment
* the RSVP counter, in case something slips up.
*/
if (!ip_rsvp_on) {
ip_rsvp_on = 1;
rsvp_on++;
}
return 0;
}
int
ip_rsvp_done(void)
{
ip_rsvpd = NULL;
/*
* This may seem silly, but we need to be sure we don't over-decrement
* the RSVP counter, in case something slips up.
*/
if (ip_rsvp_on) {
ip_rsvp_on = 0;
rsvp_on--;
}
return 0;
}
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