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NetBSD/sys/netinet6/frag6.c

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/* $NetBSD: frag6.c,v 1.56 2014/09/05 05:33:06 matt Exp $ */
/* $KAME: frag6.c,v 1.40 2002/05/27 21:40:31 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: frag6.c,v 1.56 2014/09/05 05:33:06 matt Exp $");
#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/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kmem.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 <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6_private.h>
#include <netinet/icmp6.h>
#include <net/net_osdep.h>
static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
static void frag6_deq(struct ip6asfrag *);
static void frag6_insque(struct ip6q *, struct ip6q *);
static void frag6_remque(struct ip6q *);
static void frag6_freef(struct ip6q *);
static int frag6_drainwanted;
u_int frag6_nfragpackets;
u_int frag6_nfrags;
struct ip6q ip6q; /* ip6 reassemble queue */
static kmutex_t frag6_lock;
/*
* Initialise reassembly queue and fragment identifier.
*/
void
frag6_init(void)
{
ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
mutex_init(&frag6_lock, MUTEX_DEFAULT, IPL_NET);
}
/*
* IPv6 fragment input.
*
* In RFC2460, fragment and reassembly rule do not agree with each other,
* in terms of next header field handling in fragment header.
* While the sender will use the same value for all of the fragmented packets,
* receiver is suggested not to check the consistency.
*
* fragment rule (p20):
* (2) A Fragment header containing:
* The Next Header value that identifies the first header of
* the Fragmentable Part of the original packet.
* -> next header field is same for all fragments
*
* reassembly rule (p21):
* The Next Header field of the last header of the Unfragmentable
* Part is obtained from the Next Header field of the first
* fragment's Fragment header.
* -> should grab it from the first fragment only
*
* The following note also contradicts with fragment rule - noone is going to
* send different fragment with different next header field.
*
* additional note (p22):
* The Next Header values in the Fragment headers of different
* fragments of the same original packet may differ. Only the value
* from the Offset zero fragment packet is used for reassembly.
* -> should grab it from the first fragment only
*
* There is no explicit reason given in the RFC. Historical reason maybe?
*/
int
frag6_input(struct mbuf **mp, int *offp, int proto)
{
struct rtentry *rt;
struct mbuf *m = *mp, *t;
struct ip6_hdr *ip6;
struct ip6_frag *ip6f;
struct ip6q *q6;
struct ip6asfrag *af6, *ip6af, *af6dwn;
int offset = *offp, nxt, i, next;
int first_frag = 0;
int fragoff, frgpartlen; /* must be larger than u_int16_t */
struct ifnet *dstifp;
static struct route ro;
union {
struct sockaddr dst;
struct sockaddr_in6 dst6;
} u;
ip6 = mtod(m, struct ip6_hdr *);
IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
if (ip6f == NULL)
return IPPROTO_DONE;
dstifp = NULL;
/* find the destination interface of the packet. */
sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0);
if ((rt = rtcache_lookup(&ro, &u.dst)) != NULL && rt->rt_ifa != NULL)
dstifp = ((struct in6_ifaddr *)rt->rt_ifa)->ia_ifp;
/* 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,
offsetof(struct ip6_hdr, ip6_plen));
in6_ifstat_inc(dstifp, ifs6_reass_fail);
return IPPROTO_DONE;
}
IP6_STATINC(IP6_STAT_FRAGMENTS);
in6_ifstat_inc(dstifp, ifs6_reass_reqd);
/* offset now points to data portion */
offset += sizeof(struct ip6_frag);
/*
* RFC6946: A host that receives an IPv6 packet which includes
* a Fragment Header with the "Fragmen Offset" equal to 0 and
* the "M" bit equal to 0 MUST process such packet in isolation
* from any other packets/fragments.
*/
fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
if (fragoff == 0 && !(ip6f->ip6f_offlg & IP6F_MORE_FRAG)) {
IP6_STATINC(IP6_STAT_REASSEMBLED);
in6_ifstat_inc(dstifp, ifs6_reass_ok);
*offp = offset;
return ip6f->ip6f_nxt;
}
mutex_enter(&frag6_lock);
/*
* Enforce upper bound on number of fragments.
* If maxfrag is 0, never accept fragments.
* If maxfrag is -1, accept all fragments without limitation.
*/
if (ip6_maxfrags < 0)
;
else if (frag6_nfrags >= (u_int)ip6_maxfrags)
goto dropfrag;
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;
/*
* Enforce upper bound on number of fragmented packets
* for which we attempt reassembly;
* If maxfragpackets is 0, never accept fragments.
* If maxfragpackets is -1, accept all fragments without
* limitation.
*/
if (ip6_maxfragpackets < 0)
;
else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
goto dropfrag;
frag6_nfragpackets++;
q6 = kmem_intr_zalloc(sizeof(struct ip6q), KM_NOSLEEP);
if (q6 == NULL) {
goto dropfrag;
}
frag6_insque(q6, &ip6q);
/* ip6q_nxt will be filled afterwards, from 1st fragment */
q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
#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. */
q6->ip6q_nfrag = 0;
}
/*
* If it's the 1st fragment, record the length of the
* unfragmentable part and the next header of the fragment header.
*/
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) {
mutex_exit(&frag6_lock);
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
offset - sizeof(struct ip6_frag) +
offsetof(struct ip6_frag, ip6f_offlg));
return IPPROTO_DONE;
}
} else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
mutex_exit(&frag6_lock);
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
offset - sizeof(struct ip6_frag) +
offsetof(struct ip6_frag, ip6f_offlg));
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) {
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);
kmem_intr_free(af6, sizeof(struct ip6asfrag));
/* adjust pointer. */
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) +
offsetof(struct ip6_frag, ip6f_offlg));
}
}
}
ip6af = kmem_intr_zalloc(sizeof(struct ip6asfrag), KM_NOSLEEP);
if (ip6af == NULL) {
goto dropfrag;
}
ip6af->ip6af_head = ip6->ip6_flow;
ip6af->ip6af_len = ip6->ip6_plen;
ip6af->ip6af_nxt = ip6->ip6_nxt;
ip6af->ip6af_hlim = ip6->ip6_hlim;
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 the incoming fragment overlaps some existing fragments in
* the reassembly queue - drop it as per RFC 5722.
*/
if (af6->ip6af_up != (struct ip6asfrag *)q6) {
i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
- ip6af->ip6af_off;
if (i > 0) {
kmem_intr_free(ip6af, sizeof(struct ip6asfrag));
goto dropfrag;
}
}
if (af6 != (struct ip6asfrag *)q6) {
i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
if (i > 0) {
kmem_intr_free(ip6af, sizeof(struct ip6asfrag));
goto dropfrag;
}
}
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);
frag6_nfrags++;
q6->ip6q_nfrag++;
#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) {
mutex_exit(&frag6_lock);
return IPPROTO_DONE;
}
next += af6->ip6af_frglen;
}
if (af6->ip6af_up->ip6af_mff) {
mutex_exit(&frag6_lock);
return IPPROTO_DONE;
}
/*
* Reassembly is complete; concatenate fragments.
*/
ip6af = q6->ip6q_down;
t = m = IP6_REASS_MBUF(ip6af);
af6 = ip6af->ip6af_down;
frag6_deq(ip6af);
while (af6 != (struct ip6asfrag *)q6) {
af6dwn = af6->ip6af_down;
frag6_deq(af6);
while (t->m_next)
t = t->m_next;
t->m_next = IP6_REASS_MBUF(af6);
m_adj(t->m_next, af6->ip6af_offset);
kmem_intr_free(af6, sizeof(struct ip6asfrag));
af6 = af6dwn;
}
/* adjust offset to point where the original next header starts */
offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
kmem_intr_free(ip6af, sizeof(struct ip6asfrag));
ip6 = mtod(m, struct ip6_hdr *);
ip6->ip6_plen = htons(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 (m->m_len >= offset + sizeof(struct ip6_frag)) {
memmove((char *)ip6 + sizeof(struct ip6_frag), ip6, offset);
m->m_data += sizeof(struct ip6_frag);
m->m_len -= sizeof(struct ip6_frag);
} else {
/* this comes with no copy if the boundary is on cluster */
if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
frag6_remque(q6);
frag6_nfrags -= q6->ip6q_nfrag;
kmem_intr_free(q6, sizeof(struct ip6q));
frag6_nfragpackets--;
goto dropfrag;
}
m_adj(t, sizeof(struct ip6_frag));
m_cat(m, t);
}
/*
* Store NXT to the original.
*/
{
u_int8_t *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
*prvnxtp = nxt;
}
frag6_remque(q6);
frag6_nfrags -= q6->ip6q_nfrag;
kmem_intr_free(q6, sizeof(struct ip6q));
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;
}
IP6_STATINC(IP6_STAT_REASSEMBLED);
in6_ifstat_inc(dstifp, ifs6_reass_ok);
/*
* Tell launch routine the next header
*/
*mp = m;
*offp = offset;
mutex_exit(&frag6_lock);
return nxt;
dropfrag:
mutex_exit(&frag6_lock);
in6_ifstat_inc(dstifp, ifs6_reass_fail);
IP6_STATINC(IP6_STAT_FRAGDROPPED);
m_freem(m);
return IPPROTO_DONE;
}
int
ip6_reass_packet(struct mbuf **mp, int offset)
{
if (frag6_input(mp, &offset, IPPROTO_IPV6) == IPPROTO_DONE) {
*mp = NULL;
return EINVAL;
}
return 0;
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
void
frag6_freef(struct ip6q *q6)
{
struct ip6asfrag *af6, *down6;
KASSERT(mutex_owned(&frag6_lock));
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 */
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);
}
kmem_intr_free(af6, sizeof(struct ip6asfrag));
}
frag6_remque(q6);
frag6_nfrags -= q6->ip6q_nfrag;
kmem_intr_free(q6, sizeof(struct ip6q));
frag6_nfragpackets--;
}
/*
* Put an ip fragment on a reassembly chain.
* Like insque, but pointers in middle of structure.
*/
void
frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
{
KASSERT(mutex_owned(&frag6_lock));
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(struct ip6asfrag *af6)
{
KASSERT(mutex_owned(&frag6_lock));
af6->ip6af_up->ip6af_down = af6->ip6af_down;
af6->ip6af_down->ip6af_up = af6->ip6af_up;
}
void
frag6_insque(struct ip6q *newq, struct ip6q *oldq)
{
KASSERT(mutex_owned(&frag6_lock));
newq->ip6q_prev = oldq;
newq->ip6q_next = oldq->ip6q_next;
oldq->ip6q_next->ip6q_prev= newq;
oldq->ip6q_next = newq;
}
void
frag6_remque(struct ip6q *p6)
{
KASSERT(mutex_owned(&frag6_lock));
p6->ip6q_prev->ip6q_next = p6->ip6q_next;
p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
}
void
frag6_fasttimo(void)
{
mutex_enter(softnet_lock);
KERNEL_LOCK(1, NULL);
if (frag6_drainwanted) {
frag6_drain();
frag6_drainwanted = 0;
}
KERNEL_UNLOCK_ONE(NULL);
mutex_exit(softnet_lock);
}
/*
* IPv6 reassembling timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
frag6_slowtimo(void)
{
struct ip6q *q6;
mutex_enter(softnet_lock);
KERNEL_LOCK(1, NULL);
mutex_enter(&frag6_lock);
q6 = ip6q.ip6q_next;
if (q6)
while (q6 != &ip6q) {
--q6->ip6q_ttl;
q6 = q6->ip6q_next;
if (q6->ip6q_prev->ip6q_ttl == 0) {
IP6_STATINC(IP6_STAT_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 &&
ip6q.ip6q_prev) {
IP6_STATINC(IP6_STAT_FRAGOVERFLOW);
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(ip6q.ip6q_prev);
}
mutex_exit(&frag6_lock);
KERNEL_UNLOCK_ONE(NULL);
mutex_exit(softnet_lock);
#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.
*/
rtcache_free(&ip6_forward_rt);
rtcache_free(&ipsrcchk_rt);
#endif
}
void
frag6_drainstub(void)
{
frag6_drainwanted = 1;
}
/*
* Drain off all datagram fragments.
*/
void
frag6_drain(void)
{
if (mutex_tryenter(&frag6_lock)) {
while (ip6q.ip6q_next != &ip6q) {
IP6_STATINC(IP6_STAT_FRAGDROPPED);
/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
frag6_freef(ip6q.ip6q_next);
}
mutex_exit(&frag6_lock);
}
}
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