NetBSD/sys/netinet6/frag6.c

654 lines
16 KiB
C

/* $NetBSD: frag6.c,v 1.8 2000/01/06 15:46:08 itojun Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* 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 project 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 PROJECT 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 PROJECT 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.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet6/ip6.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/icmp6.h>
#include <net/net_osdep.h>
/*
* Define it to get a correct behavior on per-interface statistics.
* You will need to perform an extra routing table lookup, per fragment,
* to do it. This may, or may not be, a performance hit.
*/
#define IN6_IFSTAT_STRICT
static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
static void frag6_deq __P((struct ip6asfrag *));
static void frag6_insque __P((struct ip6q *, struct ip6q *));
static void frag6_remque __P((struct ip6q *));
static void frag6_freef __P((struct ip6q *));
int frag6_doing_reass;
u_int frag6_nfragpackets;
struct ip6q ip6q; /* ip6 reassemble queue */
/*
* Initialise reassembly queue and fragment identifier.
*/
void
frag6_init()
{
struct timeval tv;
/*
* in many cases, random() here does NOT return random number
* as initialization during bootstrap time occur in fixed order.
*/
microtime(&tv);
ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
ip6_id = random() ^ tv.tv_usec;
}
/*
* Fragment input
*/
int
frag6_input(mp, offp, proto)
struct mbuf **mp;
int *offp, proto;
{
struct mbuf *m = *mp, *t;
struct ip6_hdr *ip6;
struct ip6_frag *ip6f;
struct ip6q *q6;
struct ip6asfrag *af6, *ip6af;
int offset = *offp, nxt, i, next;
int first_frag = 0;
u_short fragoff, frgpartlen;
struct ifnet *dstifp;
#ifdef IN6_IFSTAT_STRICT
static struct route_in6 ro;
struct sockaddr_in6 *dst;
#endif
ip6 = mtod(m, struct ip6_hdr *);
#ifndef PULLDOWN_TEST
IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
#else
IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
if (ip6f == NULL)
return IPPROTO_DONE;
#endif
dstifp = NULL;
#ifdef IN6_IFSTAT_STRICT
/* find the destination interface of the packet. */
dst = (struct sockaddr_in6 *)&ro.ro_dst;
if (ro.ro_rt
&& ((ro.ro_rt->rt_flags & RTF_UP) == 0
|| !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
RTFREE(ro.ro_rt);
ro.ro_rt = (struct rtentry *)0;
}
if (ro.ro_rt == NULL) {
bzero(dst, sizeof(*dst));
dst->sin6_family = AF_INET6;
dst->sin6_len = sizeof(struct sockaddr_in6);
dst->sin6_addr = ip6->ip6_dst;
}
rtalloc((struct route *)&ro);
if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
#else
/* we are violating the spec, this is not the destination interface */
if ((m->m_flags & M_PKTHDR) != 0)
dstifp = m->m_pkthdr.rcvif;
#endif
/* jumbo payload can't contain a fragment header */
if (ip6->ip6_plen == 0) {
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
in6_ifstat_inc(dstifp, ifs6_reass_fail);
return IPPROTO_DONE;
}
/*
* check whether fragment packet's fragment length is
* multiple of 8 octets.
* sizeof(struct ip6_frag) == 8
* sizeof(struct ip6_hdr) = 40
*/
if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
(((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
icmp6_error(m, ICMP6_PARAM_PROB,
ICMP6_PARAMPROB_HEADER,
(caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
in6_ifstat_inc(dstifp, ifs6_reass_fail);
return IPPROTO_DONE;
}
ip6stat.ip6s_fragments++;
in6_ifstat_inc(dstifp, ifs6_reass_reqd);
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
#ifdef PULLDOWN_TEST
/* XXX too strong mbuf requirement in m_pulldown() world */
#endif
offset += sizeof(struct ip6_frag);
m->m_data += offset;
m->m_len -= offset;
for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
if (ip6f->ip6f_ident == q6->ip6q_ident &&
IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
break;
if (q6 == &ip6q) {
/*
* the first fragment to arrive, create a reassembly queue.
*/
first_frag = 1;
frag6_nfragpackets++;
/*
* Enforce upper bound on number of fragmented packets
* for which we attempt reassembly;
* If maxfrag is 0, never accept fragments.
* If maxfrag is -1, accept all fragments without limitation.
*/
if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets) {
ip6stat.ip6s_fragoverflow++;
in6_ifstat_inc(dstifp, ifs6_reass_fail);
frag6_freef(ip6q.ip6q_prev);
}
q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
M_DONTWAIT);
if (q6 == NULL)
goto dropfrag;
frag6_insque(q6, &ip6q);
q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
#if 0
/*
* It is not necessarily the first segment; fragment offset
* might be non-0.
*/
q6->ip6q_nxt = ip6f->ip6f_nxt;
#endif
#ifdef notyet
q6->ip6q_nxtp = (u_char *)nxtp;
#endif
q6->ip6q_ident = ip6f->ip6f_ident;
q6->ip6q_arrive = 0; /* Is it used anywhere? */
q6->ip6q_ttl = IPV6_FRAGTTL;
q6->ip6q_src = ip6->ip6_src;
q6->ip6q_dst = ip6->ip6_dst;
q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
}
/*
* If it's the 1st fragment, record the length of the
* unfragmentable part and the next header of the fragment header.
*/
fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
if (fragoff == 0) {
q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
- sizeof(struct ip6_frag);
q6->ip6q_nxt = ip6f->ip6f_nxt;
}
/*
* Check that the reassembled packet would not exceed 65535 bytes
* in size.
* If it would exceed, discard the fragment and return an ICMP error.
*/
frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
if (q6->ip6q_unfrglen >= 0) {
/* The 1st fragment has already arrived. */
if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
m->m_data -= offset;
m->m_len += offset;
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
offset - sizeof(struct ip6_frag) + 2);
return(IPPROTO_DONE);
}
}
else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
m->m_data -= offset;
m->m_len += offset;
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
offset - sizeof(struct ip6_frag) + 2);
return(IPPROTO_DONE);
}
/*
* If it's the first fragment, do the above check for each
* fragment already stored in the reassembly queue.
*/
if (fragoff == 0) {
struct ip6asfrag *af6dwn;
for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
af6 = af6dwn) {
af6dwn = af6->ip6af_down;
if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
IPV6_MAXPACKET) {
struct mbuf *merr = IP6_REASS_MBUF(af6);
struct ip6_hdr *ip6err;
int erroff = af6->ip6af_offset;
/* dequeue the fragment. */
frag6_deq(af6);
/* adjust pointer. */
merr->m_data -= af6->ip6af_offset;
merr->m_len += af6->ip6af_offset;
ip6err = mtod(merr, struct ip6_hdr *);
/*
* Restore source and destination addresses
* in the erroneous IPv6 header.
*/
ip6err->ip6_src = q6->ip6q_src;
ip6err->ip6_dst = q6->ip6q_dst;
icmp6_error(merr, ICMP6_PARAM_PROB,
ICMP6_PARAMPROB_HEADER,
erroff - sizeof(struct ip6_frag) + 2);
}
}
}
/* Override the IPv6 header */
ip6af = (struct ip6asfrag *)ip6;
ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
ip6af->ip6af_off = fragoff;
ip6af->ip6af_frglen = frgpartlen;
ip6af->ip6af_offset = offset;
IP6_REASS_MBUF(ip6af) = m;
if (first_frag) {
af6 = (struct ip6asfrag *)q6;
goto insert;
}
/*
* Find a segment which begins after this one does.
*/
for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
af6 = af6->ip6af_down)
if (af6->ip6af_off > ip6af->ip6af_off)
break;
#if 0
/*
* 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 (af6->ip6af_up != (struct ip6asfrag *)q6) {
i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
- ip6af->ip6af_off;
if (i > 0) {
if (i >= ip6af->ip6af_frglen)
goto dropfrag;
m_adj(IP6_REASS_MBUF(ip6af), i);
ip6af->ip6af_off += i;
ip6af->ip6af_frglen -= i;
}
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
while (af6 != (struct ip6asfrag *)q6 &&
ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
if (i < af6->ip6af_frglen) {
af6->ip6af_frglen -= i;
af6->ip6af_off += i;
m_adj(IP6_REASS_MBUF(af6), i);
break;
}
af6 = af6->ip6af_down;
m_freem(IP6_REASS_MBUF(af6->ip6af_up));
frag6_deq(af6->ip6af_up);
}
#else
/*
* If the incoming framgent overlaps some existing fragments in
* the reassembly queue, drop it, since it is dangerous to override
* existing fragments from a security point of view.
*/
if (af6->ip6af_up != (struct ip6asfrag *)q6) {
i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
- ip6af->ip6af_off;
if (i > 0) {
log(LOG_ERR, "%d bytes of a fragment from %s "
"overlaps the previous fragment\n",
i, ip6_sprintf(&q6->ip6q_src));
goto dropfrag;
}
}
if (af6 != (struct ip6asfrag *)q6) {
i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
if (i > 0) {
log(LOG_ERR, "%d bytes of a fragment from %s "
"overlaps the succeeding fragment",
i, ip6_sprintf(&q6->ip6q_src));
goto dropfrag;
}
}
#endif
insert:
/*
* Stick new segment in its place;
* check for complete reassembly.
* Move to front of packet queue, as we are
* the most recently active fragmented packet.
*/
frag6_enq(ip6af, af6->ip6af_up);
#if 0 /* xxx */
if (q6 != ip6q.ip6q_next) {
frag6_remque(q6);
frag6_insque(q6, &ip6q);
}
#endif
next = 0;
for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
af6 = af6->ip6af_down) {
if (af6->ip6af_off != next) {
frag6_doing_reass = 0;
return IPPROTO_DONE;
}
next += af6->ip6af_frglen;
}
if (af6->ip6af_up->ip6af_mff) {
frag6_doing_reass = 0;
return IPPROTO_DONE;
}
/*
* Reassembly is complete; concatenate fragments.
*/
ip6af = q6->ip6q_down;
t = m = IP6_REASS_MBUF(ip6af);
af6 = ip6af->ip6af_down;
while (af6 != (struct ip6asfrag *)q6) {
while (t->m_next)
t = t->m_next;
t->m_next = IP6_REASS_MBUF(af6);
af6 = af6->ip6af_down;
}
/* adjust offset to point where the original next header starts */
offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
ip6 = (struct ip6_hdr *)ip6af;
ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
ip6->ip6_src = q6->ip6q_src;
ip6->ip6_dst = q6->ip6q_dst;
nxt = q6->ip6q_nxt;
#ifdef notyet
*q6->ip6q_nxtp = (u_char)(nxt & 0xff);
#endif
/*
* Delete frag6 header with as a few cost as possible.
*/
if (offset < m->m_len)
ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
offset);
else {
ovbcopy(mtod(m, caddr_t), (caddr_t)ip6 + offset, m->m_len);
m->m_data -= sizeof(struct ip6_frag);
}
m->m_data -= offset;
m->m_len += offset;
/*
* Store NXT to the original.
*/
{
char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
*prvnxtp = nxt;
}
frag6_remque(q6);
free(q6, M_FTABLE);
frag6_nfragpackets--;
if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
int plen = 0;
for (t = m; t; t = t->m_next)
plen += t->m_len;
m->m_pkthdr.len = plen;
}
ip6stat.ip6s_reassembled++;
in6_ifstat_inc(dstifp, ifs6_reass_ok);
/*
* Tell launch routine the next header
*/
*mp = m;
*offp = offset;
frag6_doing_reass = 0;
return nxt;
dropfrag:
in6_ifstat_inc(dstifp, ifs6_reass_fail);
ip6stat.ip6s_fragdropped++;
m_freem(m);
return IPPROTO_DONE;
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
void
frag6_freef(q6)
struct ip6q *q6;
{
struct ip6asfrag *af6, *down6;
for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
af6 = down6) {
struct mbuf *m = IP6_REASS_MBUF(af6);
down6 = af6->ip6af_down;
frag6_deq(af6);
/*
* Return ICMP time exceeded error for the 1st fragment.
* Just free other fragments.
*/
if (af6->ip6af_off == 0) {
struct ip6_hdr *ip6;
/* adjust pointer */
m->m_data -= af6->ip6af_offset;
m->m_len += af6->ip6af_offset;
ip6 = mtod(m, struct ip6_hdr *);
/* restoure source and destination addresses */
ip6->ip6_src = q6->ip6q_src;
ip6->ip6_dst = q6->ip6q_dst;
icmp6_error(m, ICMP6_TIME_EXCEEDED,
ICMP6_TIME_EXCEED_REASSEMBLY, 0);
}
else
m_freem(m);
}
frag6_remque(q6);
free(q6, M_FTABLE);
frag6_nfragpackets--;
}
/*
* Put an ip fragment on a reassembly chain.
* Like insque, but pointers in middle of structure.
*/
void
frag6_enq(af6, up6)
struct ip6asfrag *af6, *up6;
{
af6->ip6af_up = up6;
af6->ip6af_down = up6->ip6af_down;
up6->ip6af_down->ip6af_up = af6;
up6->ip6af_down = af6;
}
/*
* To frag6_enq as remque is to insque.
*/
void
frag6_deq(af6)
struct ip6asfrag *af6;
{
af6->ip6af_up->ip6af_down = af6->ip6af_down;
af6->ip6af_down->ip6af_up = af6->ip6af_up;
}
void
frag6_insque(new, old)
struct ip6q *new, *old;
{
new->ip6q_prev = old;
new->ip6q_next = old->ip6q_next;
old->ip6q_next->ip6q_prev= new;
old->ip6q_next = new;
}
void
frag6_remque(p6)
struct ip6q *p6;
{
p6->ip6q_prev->ip6q_next = p6->ip6q_next;
p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
}
/*
* IP timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
frag6_slowtimo()
{
struct ip6q *q6;
int s = splsoftnet();
#if 0
extern struct route_in6 ip6_forward_rt;
#endif
frag6_doing_reass = 1;
q6 = ip6q.ip6q_next;
if (q6)
while (q6 != &ip6q) {
--q6->ip6q_ttl;
q6 = q6->ip6q_next;
if (q6->ip6q_prev->ip6q_ttl == 0) {
ip6stat.ip6s_fragtimeout++;
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(q6->ip6q_prev);
}
}
/*
* If we are over the maximum number of fragments
* (due to the limit being lowered), drain off
* enough to get down to the new limit.
*/
while (frag6_nfragpackets > (u_int)ip6_maxfragpackets) {
ip6stat.ip6s_fragoverflow++;
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(ip6q.ip6q_prev);
}
frag6_doing_reass = 0;
#if 0
/*
* Routing changes might produce a better route than we last used;
* make sure we notice eventually, even if forwarding only for one
* destination and the cache is never replaced.
*/
if (ip6_forward_rt.ro_rt) {
RTFREE(ip6_forward_rt.ro_rt);
ip6_forward_rt.ro_rt = 0;
}
if (ipsrcchk_rt.ro_rt) {
RTFREE(ipsrcchk_rt.ro_rt);
ipsrcchk_rt.ro_rt = 0;
}
#endif
splx(s);
}
/*
* Drain off all datagram fragments.
*/
void
frag6_drain()
{
if (frag6_doing_reass)
return;
while (ip6q.ip6q_next != &ip6q) {
ip6stat.ip6s_fragdropped++;
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(ip6q.ip6q_next);
}
}