574 lines
14 KiB
C
574 lines
14 KiB
C
/*
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* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/domain.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/errno.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/syslog.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_var.h>
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#include <netinet6/ip6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/icmp6.h>
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#include <net/net_osdep.h>
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/*
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* Define it to get a correct behavior on per-interface statistics.
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* You will need to perform an extra routing table lookup, per fragment,
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* to do it. This may, or may not be, a performance hit.
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*/
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#define IN6_IFSTAT_STRICT
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static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
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static void frag6_deq __P((struct ip6asfrag *));
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static void frag6_insque __P((struct ip6q *, struct ip6q *));
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static void frag6_remque __P((struct ip6q *));
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static void frag6_freef __P((struct ip6q *));
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int frag6_doing_reass;
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u_int frag6_nfragpackets;
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struct ip6q ip6q; /* ip6 reassemble queue */
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#if !defined(M_FTABLE)
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MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
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#endif
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/*
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* Initialise reassembly queue and fragment identifier.
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*/
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void
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frag6_init()
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{
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struct timeval tv;
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/*
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* in many cases, random() here does NOT return random number
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* as initialization during bootstrap time occur in fixed order.
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*/
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microtime(&tv);
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ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
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ip6_id = random() ^ tv.tv_usec;
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}
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/*
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* Fragment input
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*/
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int
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frag6_input(mp, offp, proto)
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struct mbuf **mp;
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int *offp, proto;
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{
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struct mbuf *m = *mp, *t;
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struct ip6_hdr *ip6;
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struct ip6_frag *ip6f;
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struct ip6q *q6;
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struct ip6asfrag *af6, *ip6af;
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int offset = *offp, nxt, i, next;
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int first_frag = 0;
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u_short fragoff, frgpartlen;
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struct ifnet *dstifp;
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#ifdef IN6_IFSTAT_STRICT
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static struct route_in6 ro;
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struct sockaddr_in6 *dst;
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#endif
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IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
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ip6 = mtod(m, struct ip6_hdr *);
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ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
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dstifp = NULL;
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#ifdef IN6_IFSTAT_STRICT
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/* find the destination interface of the packet. */
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dst = (struct sockaddr_in6 *)&ro.ro_dst;
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if (ro.ro_rt
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&& ((ro.ro_rt->rt_flags & RTF_UP) == 0
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|| !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
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RTFREE(ro.ro_rt);
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ro.ro_rt = (struct rtentry *)0;
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}
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if (ro.ro_rt == NULL) {
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bzero(dst, sizeof(*dst));
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dst->sin6_family = AF_INET6;
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dst->sin6_len = sizeof(struct sockaddr_in6);
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dst->sin6_addr = ip6->ip6_dst;
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}
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rtalloc((struct route *)&ro);
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if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
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dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
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#else
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/* we are violating the spec, this is not the destination interface */
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if ((m->m_flags & M_PKTHDR) != 0)
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dstifp = m->m_pkthdr.rcvif;
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#endif
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/* jumbo payload can't contain a fragment header */
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if (ip6->ip6_plen == 0) {
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icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
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in6_ifstat_inc(dstifp, ifs6_reass_fail);
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return IPPROTO_DONE;
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}
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/*
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* check whether fragment packet's fragment length is
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* multiple of 8 octets.
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* sizeof(struct ip6_frag) == 8
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* sizeof(struct ip6_hdr) = 40
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*/
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if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
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(((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
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icmp6_error(m, ICMP6_PARAM_PROB,
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ICMP6_PARAMPROB_HEADER,
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(caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
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in6_ifstat_inc(dstifp, ifs6_reass_fail);
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return IPPROTO_DONE;
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}
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ip6stat.ip6s_fragments++;
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in6_ifstat_inc(dstifp, ifs6_reass_reqd);
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/*
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* Presence of header sizes in mbufs
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* would confuse code below.
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*/
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offset += sizeof(struct ip6_frag);
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m->m_data += offset;
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m->m_len -= offset;
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for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
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if (ip6f->ip6f_ident == q6->ip6q_ident &&
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IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
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IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
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break;
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if (q6 == &ip6q) {
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/*
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* the first fragment to arrive, create a reassembly queue.
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*/
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first_frag = 1;
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frag6_nfragpackets++;
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/*
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* Enforce upper bound on number of fragmented packets
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* for which we attempt reassembly;
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* If maxfrag is 0, never accept fragments.
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* If maxfrag is -1, accept all fragments without limitation.
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*/
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if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets) {
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ip6stat.ip6s_fragoverflow++;
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in6_ifstat_inc(dstifp, ifs6_reass_fail);
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frag6_freef(ip6q.ip6q_prev);
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}
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q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
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M_DONTWAIT);
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if (q6 == NULL)
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goto dropfrag;
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frag6_insque(q6, &ip6q);
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q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
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q6->ip6q_ident = ip6f->ip6f_ident;
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q6->ip6q_arrive = 0; /* Is it used anywhere? */
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q6->ip6q_ttl = IPV6_FRAGTTL;
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q6->ip6q_src = ip6->ip6_src;
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q6->ip6q_dst = ip6->ip6_dst;
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q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
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}
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/*
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* If it's the 1st fragment, record the length of the
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* unfragmentable part and the next header of the fragment header.
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*/
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fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
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if (fragoff == 0) {
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q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
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- sizeof(struct ip6_frag);
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q6->ip6q_nxt = ip6f->ip6f_nxt;
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}
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/*
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* Check that the reassembled packet would not exceed 65535 bytes
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* in size.
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* If it would exceed, discard the fragment and return an ICMP error.
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*/
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frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
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if (q6->ip6q_unfrglen >= 0) {
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/* The 1st fragment has already arrived. */
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if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
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m->m_data -= offset;
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m->m_len += offset;
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icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
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offset - sizeof(struct ip6_frag) + 2);
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return(IPPROTO_DONE);
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}
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}
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else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
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m->m_data -= offset;
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m->m_len += offset;
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icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
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offset - sizeof(struct ip6_frag) + 2);
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return(IPPROTO_DONE);
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}
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/*
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* If it's the first fragment, do the above check for each
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* fragment already stored in the reassembly queue.
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*/
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if (fragoff == 0) {
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struct ip6asfrag *af6dwn;
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for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
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af6 = af6dwn) {
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af6dwn = af6->ip6af_down;
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if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
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IPV6_MAXPACKET) {
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struct mbuf *merr = IP6_REASS_MBUF(af6);
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struct ip6_hdr *ip6err;
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int erroff = af6->ip6af_offset;
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/* dequeue the fragment. */
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frag6_deq(af6);
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/* adjust pointer. */
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merr->m_data -= af6->ip6af_offset;
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merr->m_len += af6->ip6af_offset;
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ip6err = mtod(merr, struct ip6_hdr *);
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/*
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* Restore source and destination addresses
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* in the erroneous IPv6 header.
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*/
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ip6err->ip6_src = q6->ip6q_src;
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ip6err->ip6_dst = q6->ip6q_dst;
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icmp6_error(merr, ICMP6_PARAM_PROB,
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ICMP6_PARAMPROB_HEADER,
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erroff - sizeof(struct ip6_frag) + 2);
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}
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}
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}
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/* Override the IPv6 header */
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ip6af = (struct ip6asfrag *)ip6;
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ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
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ip6af->ip6af_off = fragoff;
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ip6af->ip6af_frglen = frgpartlen;
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ip6af->ip6af_offset = offset;
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IP6_REASS_MBUF(ip6af) = m;
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if (first_frag) {
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af6 = (struct ip6asfrag *)q6;
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goto insert;
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}
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/*
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* Find a segment which begins after this one does.
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*/
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for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
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af6 = af6->ip6af_down)
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if (af6->ip6af_off > ip6af->ip6af_off)
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break;
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/*
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* If the incoming framgent overlaps some existing fragments in
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* the reassembly queue, drop it, since it is dangerous to override
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* existing fragments from a security point of view.
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*/
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if (af6->ip6af_up != (struct ip6asfrag *)q6) {
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i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
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- ip6af->ip6af_off;
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if (i > 0) {
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log(LOG_ERR, "%d bytes of a fragment from %s "
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"overlaps the previous fragment\n",
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i, ip6_sprintf(&q6->ip6q_src));
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goto dropfrag;
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}
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}
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if (af6 != (struct ip6asfrag *)q6) {
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i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
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if (i > 0) {
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log(LOG_ERR, "%d bytes of a fragment from %s "
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"overlaps the succeeding fragment",
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i, ip6_sprintf(&q6->ip6q_src));
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goto dropfrag;
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}
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}
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insert:
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/*
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* Stick new segment in its place;
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* check for complete reassembly.
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* Move to front of packet queue, as we are
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* the most recently active fragmented packet.
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*/
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frag6_enq(ip6af, af6->ip6af_up);
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next = 0;
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for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
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af6 = af6->ip6af_down) {
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if (af6->ip6af_off != next) {
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frag6_doing_reass = 0;
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return IPPROTO_DONE;
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}
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next += af6->ip6af_frglen;
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}
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if (af6->ip6af_up->ip6af_mff) {
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frag6_doing_reass = 0;
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return IPPROTO_DONE;
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}
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/*
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* Reassembly is complete; concatenate fragments.
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*/
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ip6af = q6->ip6q_down;
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t = m = IP6_REASS_MBUF(ip6af);
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af6 = ip6af->ip6af_down;
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while (af6 != (struct ip6asfrag *)q6) {
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while (t->m_next)
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t = t->m_next;
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t->m_next = IP6_REASS_MBUF(af6);
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af6 = af6->ip6af_down;
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}
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/* adjust offset to point where the original next header starts */
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offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
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ip6 = (struct ip6_hdr *)ip6af;
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ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
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ip6->ip6_src = q6->ip6q_src;
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ip6->ip6_dst = q6->ip6q_dst;
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nxt = q6->ip6q_nxt;
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/*
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* Delete frag6 header with as a few cost as possible.
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*/
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if (offset < m->m_len)
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ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
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offset);
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else {
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ovbcopy(mtod(m, caddr_t), (caddr_t)ip6 + offset, m->m_len);
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m->m_data -= sizeof(struct ip6_frag);
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}
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m->m_data -= offset;
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m->m_len += offset;
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/*
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* Store NXT to the original.
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*/
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{
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char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
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*prvnxtp = nxt;
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}
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frag6_remque(q6);
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free(q6, M_FTABLE);
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frag6_nfragpackets--;
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if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
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int plen = 0;
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for (t = m; t; t = t->m_next)
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plen += t->m_len;
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m->m_pkthdr.len = plen;
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}
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ip6stat.ip6s_reassembled++;
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in6_ifstat_inc(dstifp, ifs6_reass_ok);
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/*
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* Tell launch routine the next header
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*/
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*mp = m;
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*offp = offset;
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frag6_doing_reass = 0;
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return nxt;
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dropfrag:
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in6_ifstat_inc(dstifp, ifs6_reass_fail);
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ip6stat.ip6s_fragdropped++;
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m_freem(m);
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return IPPROTO_DONE;
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}
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/*
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* Free a fragment reassembly header and all
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* associated datagrams.
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*/
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void
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frag6_freef(q6)
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struct ip6q *q6;
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{
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struct ip6asfrag *af6, *down6;
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for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
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af6 = down6) {
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struct mbuf *m = IP6_REASS_MBUF(af6);
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down6 = af6->ip6af_down;
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frag6_deq(af6);
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/*
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* Return ICMP time exceeded error for the 1st fragment.
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* Just free other fragments.
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*/
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if (af6->ip6af_off == 0) {
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struct ip6_hdr *ip6;
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/* adjust pointer */
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m->m_data -= af6->ip6af_offset;
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m->m_len += af6->ip6af_offset;
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ip6 = mtod(m, struct ip6_hdr *);
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/* restoure source and destination addresses */
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ip6->ip6_src = q6->ip6q_src;
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ip6->ip6_dst = q6->ip6q_dst;
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icmp6_error(m, ICMP6_TIME_EXCEEDED,
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ICMP6_TIME_EXCEED_REASSEMBLY, 0);
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}
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else
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m_freem(m);
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}
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frag6_remque(q6);
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free(q6, M_FTABLE);
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|
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 = splnet();
|
|
|
|
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;
|
|
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);
|
|
}
|
|
}
|