/
ip_input.c
1796 lines (1625 loc) · 43.6 KB
/
ip_input.c
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/* $OpenBSD: ip_input.c,v 1.349 2020/08/01 23:41:55 gnezdo Exp $ */
/* $NetBSD: ip_input.c,v 1.30 1996/03/16 23:53:58 christos Exp $ */
/*
* 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. 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
*/
#include "pf.h"
#include "carp.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/mutex.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/pool.h>
#include <sys/task.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/if_ether.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <net/if_types.h>
#ifdef INET6
#include <netinet6/ip6protosw.h>
#include <netinet6/ip6_var.h>
#endif
#if NPF > 0
#include <net/pfvar.h>
#endif
#ifdef MROUTING
#include <netinet/ip_mroute.h>
#endif
#ifdef IPSEC
#include <netinet/ip_ipsp.h>
#endif /* IPSEC */
#if NCARP > 0
#include <netinet/ip_carp.h>
#endif
/* values controllable via sysctl */
int ipforwarding = 0;
int ipmforwarding = 0;
int ipmultipath = 0;
int ipsendredirects = 1;
int ip_dosourceroute = 0;
int ip_defttl = IPDEFTTL;
int ip_mtudisc = 1;
u_int ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
int ip_directedbcast = 0;
struct rttimer_queue *ip_mtudisc_timeout_q = NULL;
/* Protects `ipq' and `ip_frags'. */
struct mutex ipq_mutex = MUTEX_INITIALIZER(IPL_SOFTNET);
/* IP reassembly queue */
LIST_HEAD(, ipq) ipq;
/* Keep track of memory used for reassembly */
int ip_maxqueue = 300;
int ip_frags = 0;
int *ipctl_vars[IPCTL_MAXID] = IPCTL_VARS;
struct pool ipqent_pool;
struct pool ipq_pool;
struct cpumem *ipcounters;
int ip_sysctl_ipstat(void *, size_t *, void *);
static struct mbuf_queue ipsend_mq;
extern struct niqueue arpinq;
int ip_ours(struct mbuf **, int *, int, int);
int ip_dooptions(struct mbuf *, struct ifnet *);
int in_ouraddr(struct mbuf *, struct ifnet *, struct rtentry **);
static void ip_send_dispatch(void *);
static struct task ipsend_task = TASK_INITIALIZER(ip_send_dispatch, &ipsend_mq);
/*
* Used 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.
*/
struct ip_srcrt {
int isr_nhops; /* number of hops */
struct in_addr isr_dst; /* final destination */
char isr_nop; /* one NOP to align */
char isr_hdr[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN & OFFSET */
struct in_addr isr_routes[MAX_IPOPTLEN/sizeof(struct in_addr)];
};
void save_rte(struct mbuf *, u_char *, struct in_addr);
/*
* IP initialization: fill in IP protocol switch table.
* All protocols not implemented in kernel go to raw IP protocol handler.
*/
void
ip_init(void)
{
const struct protosw *pr;
int i;
const u_int16_t defbaddynamicports_tcp[] = DEFBADDYNAMICPORTS_TCP;
const u_int16_t defbaddynamicports_udp[] = DEFBADDYNAMICPORTS_UDP;
const u_int16_t defrootonlyports_tcp[] = DEFROOTONLYPORTS_TCP;
const u_int16_t defrootonlyports_udp[] = DEFROOTONLYPORTS_UDP;
ipcounters = counters_alloc(ips_ncounters);
pool_init(&ipqent_pool, sizeof(struct ipqent), 0,
IPL_SOFTNET, 0, "ipqe", NULL);
pool_init(&ipq_pool, sizeof(struct ipq), 0,
IPL_SOFTNET, 0, "ipq", NULL);
pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
if (pr == NULL)
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 &&
pr->pr_protocol < IPPROTO_MAX)
ip_protox[pr->pr_protocol] = pr - inetsw;
LIST_INIT(&ipq);
if (ip_mtudisc != 0)
ip_mtudisc_timeout_q =
rt_timer_queue_create(ip_mtudisc_timeout);
/* Fill in list of ports not to allocate dynamically. */
memset(&baddynamicports, 0, sizeof(baddynamicports));
for (i = 0; defbaddynamicports_tcp[i] != 0; i++)
DP_SET(baddynamicports.tcp, defbaddynamicports_tcp[i]);
for (i = 0; defbaddynamicports_udp[i] != 0; i++)
DP_SET(baddynamicports.udp, defbaddynamicports_udp[i]);
/* Fill in list of ports only root can bind to. */
memset(&rootonlyports, 0, sizeof(rootonlyports));
for (i = 0; defrootonlyports_tcp[i] != 0; i++)
DP_SET(rootonlyports.tcp, defrootonlyports_tcp[i]);
for (i = 0; defrootonlyports_udp[i] != 0; i++)
DP_SET(rootonlyports.udp, defrootonlyports_udp[i]);
mq_init(&ipsend_mq, 64, IPL_SOFTNET);
#ifdef IPSEC
ipsec_init();
#endif
}
/*
* IPv4 input routine.
*
* Checksum and byte swap header. Process options. Forward or deliver.
*/
void
ipv4_input(struct ifnet *ifp, struct mbuf *m)
{
int off, nxt;
off = 0;
nxt = ip_input_if(&m, &off, IPPROTO_IPV4, AF_UNSPEC, ifp);
KASSERT(nxt == IPPROTO_DONE);
}
int
ip_input_if(struct mbuf **mp, int *offp, int nxt, int af, struct ifnet *ifp)
{
struct mbuf *m = *mp;
struct rtentry *rt = NULL;
struct ip *ip;
int hlen, len;
in_addr_t pfrdr = 0;
KASSERT(*offp == 0);
ipstat_inc(ips_total);
if (m->m_len < sizeof (struct ip) &&
(m = *mp = m_pullup(m, sizeof (struct ip))) == NULL) {
ipstat_inc(ips_toosmall);
goto bad;
}
ip = mtod(m, struct ip *);
if (ip->ip_v != IPVERSION) {
ipstat_inc(ips_badvers);
goto bad;
}
hlen = ip->ip_hl << 2;
if (hlen < sizeof(struct ip)) { /* minimum header length */
ipstat_inc(ips_badhlen);
goto bad;
}
if (hlen > m->m_len) {
if ((m = *mp = m_pullup(m, hlen)) == NULL) {
ipstat_inc(ips_badhlen);
goto bad;
}
ip = mtod(m, struct ip *);
}
/* 127/8 must not appear on wire - RFC1122 */
if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
(ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
ipstat_inc(ips_badaddr);
goto bad;
}
}
if ((m->m_pkthdr.csum_flags & M_IPV4_CSUM_IN_OK) == 0) {
if (m->m_pkthdr.csum_flags & M_IPV4_CSUM_IN_BAD) {
ipstat_inc(ips_badsum);
goto bad;
}
ipstat_inc(ips_inswcsum);
if (in_cksum(m, hlen) != 0) {
ipstat_inc(ips_badsum);
goto bad;
}
}
/* Retrieve the packet length. */
len = ntohs(ip->ip_len);
/*
* Convert fields to host representation.
*/
if (len < hlen) {
ipstat_inc(ips_badlen);
goto bad;
}
/*
* Check that the amount of data in the buffers
* is at least as 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 < len) {
ipstat_inc(ips_tooshort);
goto bad;
}
if (m->m_pkthdr.len > len) {
if (m->m_len == m->m_pkthdr.len) {
m->m_len = len;
m->m_pkthdr.len = len;
} else
m_adj(m, len - m->m_pkthdr.len);
}
#if NCARP > 0
if (carp_lsdrop(ifp, m, AF_INET, &ip->ip_src.s_addr,
&ip->ip_dst.s_addr, (ip->ip_p == IPPROTO_ICMP ? 0 : 1)))
goto bad;
#endif
#if NPF > 0
/*
* Packet filter
*/
pfrdr = ip->ip_dst.s_addr;
if (pf_test(AF_INET, PF_IN, ifp, mp) != PF_PASS)
goto bad;
m = *mp;
if (m == NULL)
goto bad;
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
pfrdr = (pfrdr != ip->ip_dst.s_addr);
#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).
*/
if (hlen > sizeof (struct ip) && ip_dooptions(m, ifp)) {
m = *mp = NULL;
goto bad;
}
if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
ip->ip_dst.s_addr == INADDR_ANY) {
nxt = ip_ours(mp, offp, nxt, af);
goto out;
}
switch(in_ouraddr(m, ifp, &rt)) {
case 2:
goto bad;
case 1:
nxt = ip_ours(mp, offp, nxt, af);
goto out;
}
if (IN_MULTICAST(ip->ip_dst.s_addr)) {
/*
* Make sure M_MCAST is set. It should theoretically
* already be there, but let's play safe because upper
* layers check for this flag.
*/
m->m_flags |= M_MCAST;
#ifdef MROUTING
if (ipmforwarding && ip_mrouter[ifp->if_rdomain]) {
int error;
if (m->m_flags & M_EXT) {
if ((m = *mp = m_pullup(m, hlen)) == NULL) {
ipstat_inc(ips_toosmall);
goto bad;
}
ip = mtod(m, struct ip *);
}
/*
* 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().)
*/
KERNEL_LOCK();
error = ip_mforward(m, ifp);
KERNEL_UNLOCK();
if (error) {
ipstat_inc(ips_cantforward);
goto bad;
}
/*
* The process-level routing daemon needs to receive
* all multicast IGMP packets, whether or not this
* host belongs to their destination groups.
*/
if (ip->ip_p == IPPROTO_IGMP) {
nxt = ip_ours(mp, offp, nxt, af);
goto out;
}
ipstat_inc(ips_forward);
}
#endif
/*
* See if we belong to the destination multicast group on the
* arrival interface.
*/
if (!in_hasmulti(&ip->ip_dst, ifp)) {
ipstat_inc(ips_notmember);
if (!IN_LOCAL_GROUP(ip->ip_dst.s_addr))
ipstat_inc(ips_cantforward);
goto bad;
}
nxt = ip_ours(mp, offp, nxt, af);
goto out;
}
#if NCARP > 0
if (ip->ip_p == IPPROTO_ICMP &&
carp_lsdrop(ifp, m, AF_INET, &ip->ip_src.s_addr,
&ip->ip_dst.s_addr, 1))
goto bad;
#endif
/*
* Not for us; forward if possible and desirable.
*/
if (ipforwarding == 0) {
ipstat_inc(ips_cantforward);
goto bad;
}
#ifdef IPSEC
if (ipsec_in_use) {
int rv;
rv = ipsec_forward_check(m, hlen, AF_INET);
if (rv != 0) {
ipstat_inc(ips_cantforward);
goto bad;
}
/*
* Fall through, forward packet. Outbound IPsec policy
* checking will occur in ip_output().
*/
}
#endif /* IPSEC */
ip_forward(m, ifp, rt, pfrdr);
*mp = NULL;
return IPPROTO_DONE;
bad:
nxt = IPPROTO_DONE;
m_freemp(mp);
out:
rtfree(rt);
return nxt;
}
/*
* IPv4 local-delivery routine.
*
* If fragmented try to reassemble. Pass to next level.
*/
int
ip_ours(struct mbuf **mp, int *offp, int nxt, int af)
{
struct mbuf *m = *mp;
struct ip *ip = mtod(m, struct ip *);
struct ipq *fp;
struct ipqent *ipqe;
int mff, hlen;
hlen = ip->ip_hl << 2;
/*
* 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 &~ htons(IP_DF | IP_RF)) {
if (m->m_flags & M_EXT) { /* XXX */
if ((m = *mp = m_pullup(m, hlen)) == NULL) {
ipstat_inc(ips_toosmall);
return IPPROTO_DONE;
}
ip = mtod(m, struct ip *);
}
mtx_enter(&ipq_mutex);
/*
* Look for queue of fragments
* of this datagram.
*/
LIST_FOREACH(fp, &ipq, ipq_q) {
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)
break;
}
/*
* Adjust ip_len to not reflect header,
* set ipqe_mff if more fragments are expected,
* convert offset of this to bytes.
*/
ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
mff = (ip->ip_off & htons(IP_MF)) != 0;
if (mff) {
/*
* Make sure that fragments have a data length
* that's a non-zero multiple of 8 bytes.
*/
if (ntohs(ip->ip_len) == 0 ||
(ntohs(ip->ip_len) & 0x7) != 0) {
ipstat_inc(ips_badfrags);
goto bad;
}
}
ip->ip_off = htons(ntohs(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 (mff || ip->ip_off) {
ipstat_inc(ips_fragments);
if (ip_frags + 1 > ip_maxqueue) {
ip_flush();
ipstat_inc(ips_rcvmemdrop);
goto bad;
}
ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
if (ipqe == NULL) {
ipstat_inc(ips_rcvmemdrop);
goto bad;
}
ip_frags++;
ipqe->ipqe_mff = mff;
ipqe->ipqe_m = m;
ipqe->ipqe_ip = ip;
m = *mp = ip_reass(ipqe, fp);
if (m == NULL)
goto bad;
ipstat_inc(ips_reassembled);
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
ip->ip_len = htons(ntohs(ip->ip_len) + hlen);
} else
if (fp)
ip_freef(fp);
mtx_leave(&ipq_mutex);
}
*offp = hlen;
nxt = ip->ip_p;
/* Check wheter we are already in a IPv4/IPv6 local deliver loop. */
if (af == AF_UNSPEC)
nxt = ip_deliver(mp, offp, nxt, AF_INET);
return nxt;
bad:
mtx_leave(&ipq_mutex);
m_freemp(mp);
return IPPROTO_DONE;
}
#ifndef INET6
#define IPSTAT_INC(name) ipstat_inc(ips_##name)
#else
#define IPSTAT_INC(name) (af == AF_INET ? \
ipstat_inc(ips_##name) : ip6stat_inc(ip6s_##name))
#endif
int
ip_deliver(struct mbuf **mp, int *offp, int nxt, int af)
{
const struct protosw *psw;
int naf = af;
#ifdef INET6
int nest = 0;
#endif /* INET6 */
/* pf might have modified stuff, might have to chksum */
switch (af) {
case AF_INET:
in_proto_cksum_out(*mp, NULL);
break;
#ifdef INET6
case AF_INET6:
in6_proto_cksum_out(*mp, NULL);
break;
#endif /* INET6 */
}
/*
* Tell launch routine the next header
*/
IPSTAT_INC(delivered);
while (nxt != IPPROTO_DONE) {
#ifdef INET6
if (af == AF_INET6 &&
ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) {
ip6stat_inc(ip6s_toomanyhdr);
goto bad;
}
#endif /* INET6 */
/*
* protection against faulty packet - there should be
* more sanity checks in header chain processing.
*/
if ((*mp)->m_pkthdr.len < *offp) {
IPSTAT_INC(tooshort);
goto bad;
}
#ifdef INET6
/* draft-itojun-ipv6-tcp-to-anycast */
if (af == AF_INET6 &&
ISSET((*mp)->m_flags, M_ACAST) && (nxt == IPPROTO_TCP)) {
if ((*mp)->m_len >= sizeof(struct ip6_hdr)) {
icmp6_error(*mp, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_ADDR,
offsetof(struct ip6_hdr, ip6_dst));
*mp = NULL;
}
goto bad;
}
#endif /* INET6 */
#ifdef IPSEC
if (ipsec_in_use) {
if (ipsec_local_check(*mp, *offp, nxt, af) != 0) {
IPSTAT_INC(cantforward);
goto bad;
}
}
/* Otherwise, just fall through and deliver the packet */
#endif /* IPSEC */
switch (nxt) {
case IPPROTO_IPV4:
naf = AF_INET;
ipstat_inc(ips_delivered);
break;
#ifdef INET6
case IPPROTO_IPV6:
naf = AF_INET6;
ip6stat_inc(ip6s_delivered);
break;
#endif /* INET6 */
}
switch (af) {
case AF_INET:
psw = &inetsw[ip_protox[nxt]];
break;
#ifdef INET6
case AF_INET6:
psw = &inet6sw[ip6_protox[nxt]];
break;
#endif /* INET6 */
}
nxt = (*psw->pr_input)(mp, offp, nxt, af);
af = naf;
}
return nxt;
bad:
m_freemp(mp);
return IPPROTO_DONE;
}
#undef IPSTAT_INC
int
in_ouraddr(struct mbuf *m, struct ifnet *ifp, struct rtentry **prt)
{
struct rtentry *rt;
struct ip *ip;
struct sockaddr_in sin;
int match = 0;
#if NPF > 0
switch (pf_ouraddr(m)) {
case 0:
return (0);
case 1:
return (1);
default:
/* pf does not know it */
break;
}
#endif
ip = mtod(m, struct ip *);
memset(&sin, 0, sizeof(sin));
sin.sin_len = sizeof(sin);
sin.sin_family = AF_INET;
sin.sin_addr = ip->ip_dst;
rt = rtalloc_mpath(sintosa(&sin), &ip->ip_src.s_addr,
m->m_pkthdr.ph_rtableid);
if (rtisvalid(rt)) {
if (ISSET(rt->rt_flags, RTF_LOCAL))
match = 1;
/*
* If directedbcast is enabled we only consider it local
* if it is received on the interface with that address.
*/
if (ISSET(rt->rt_flags, RTF_BROADCAST) &&
(!ip_directedbcast || rt->rt_ifidx == ifp->if_index)) {
match = 1;
/* Make sure M_BCAST is set */
m->m_flags |= M_BCAST;
}
}
*prt = rt;
if (!match) {
struct ifaddr *ifa;
/*
* No local address or broadcast address found, so check for
* ancient classful broadcast addresses.
* It must have been broadcast on the link layer, and for an
* address on the interface it was received on.
*/
if (!ISSET(m->m_flags, M_BCAST) ||
!IN_CLASSFULBROADCAST(ip->ip_dst.s_addr, ip->ip_dst.s_addr))
return (0);
if (ifp->if_rdomain != rtable_l2(m->m_pkthdr.ph_rtableid))
return (0);
/*
* The check in the loop assumes you only rx a packet on an UP
* interface, and that M_BCAST will only be set on a BROADCAST
* interface.
*/
NET_ASSERT_LOCKED();
TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
if (IN_CLASSFULBROADCAST(ip->ip_dst.s_addr,
ifatoia(ifa)->ia_addr.sin_addr.s_addr)) {
match = 1;
break;
}
}
} else if (ipforwarding == 0 && rt->rt_ifidx != ifp->if_index &&
!((ifp->if_flags & IFF_LOOPBACK) || (ifp->if_type == IFT_ENC) ||
(m->m_pkthdr.pf.flags & PF_TAG_TRANSLATE_LOCALHOST))) {
/* received on wrong interface. */
#if NCARP > 0
struct ifnet *out_if;
/*
* Virtual IPs on carp interfaces need to be checked also
* against the parent interface and other carp interfaces
* sharing the same parent.
*/
out_if = if_get(rt->rt_ifidx);
if (!(out_if && carp_strict_addr_chk(out_if, ifp))) {
ipstat_inc(ips_wrongif);
match = 2;
}
if_put(out_if);
#else
ipstat_inc(ips_wrongif);
match = 2;
#endif
}
return (match);
}
/*
* 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.
*/
struct mbuf *
ip_reass(struct ipqent *ipqe, struct ipq *fp)
{
struct mbuf *m = ipqe->ipqe_m;
struct ipqent *nq, *p, *q;
struct ip *ip;
struct mbuf *t;
int hlen = ipqe->ipqe_ip->ip_hl << 2;
int i, next;
u_int8_t ecn, ecn0;
MUTEX_ASSERT_LOCKED(&ipq_mutex);
/*
* 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 == NULL) {
fp = pool_get(&ipq_pool, PR_NOWAIT);
if (fp == NULL)
goto dropfrag;
LIST_INSERT_HEAD(&ipq, fp, ipq_q);
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ipqe->ipqe_ip->ip_p;
fp->ipq_id = ipqe->ipqe_ip->ip_id;
LIST_INIT(&fp->ipq_fragq);
fp->ipq_src = ipqe->ipqe_ip->ip_src;
fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
p = NULL;
goto insert;
}
/*
* Handle ECN by comparing this segment with the first one;
* if CE is set, do not lose CE.
* drop if CE and not-ECT are mixed for the same packet.
*/
ecn = ipqe->ipqe_ip->ip_tos & IPTOS_ECN_MASK;
ecn0 = LIST_FIRST(&fp->ipq_fragq)->ipqe_ip->ip_tos & IPTOS_ECN_MASK;
if (ecn == IPTOS_ECN_CE) {
if (ecn0 == IPTOS_ECN_NOTECT)
goto dropfrag;
if (ecn0 != IPTOS_ECN_CE)
LIST_FIRST(&fp->ipq_fragq)->ipqe_ip->ip_tos |=
IPTOS_ECN_CE;
}
if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
goto dropfrag;
/*
* Find a segment which begins after this one does.
*/
for (p = NULL, q = LIST_FIRST(&fp->ipq_fragq); q != NULL;
p = q, q = LIST_NEXT(q, ipqe_q))
if (ntohs(q->ipqe_ip->ip_off) > ntohs(ipqe->ipqe_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 (p != NULL) {
i = ntohs(p->ipqe_ip->ip_off) + ntohs(p->ipqe_ip->ip_len) -
ntohs(ipqe->ipqe_ip->ip_off);
if (i > 0) {
if (i >= ntohs(ipqe->ipqe_ip->ip_len))
goto dropfrag;
m_adj(ipqe->ipqe_m, i);
ipqe->ipqe_ip->ip_off =
htons(ntohs(ipqe->ipqe_ip->ip_off) + i);
ipqe->ipqe_ip->ip_len =
htons(ntohs(ipqe->ipqe_ip->ip_len) - i);
}
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
for (; q != NULL &&
ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len) >
ntohs(q->ipqe_ip->ip_off); q = nq) {
i = (ntohs(ipqe->ipqe_ip->ip_off) +
ntohs(ipqe->ipqe_ip->ip_len)) - ntohs(q->ipqe_ip->ip_off);
if (i < ntohs(q->ipqe_ip->ip_len)) {
q->ipqe_ip->ip_len =
htons(ntohs(q->ipqe_ip->ip_len) - i);
q->ipqe_ip->ip_off =
htons(ntohs(q->ipqe_ip->ip_off) + i);
m_adj(q->ipqe_m, i);
break;
}
nq = LIST_NEXT(q, ipqe_q);
m_freem(q->ipqe_m);
LIST_REMOVE(q, ipqe_q);
pool_put(&ipqent_pool, q);
ip_frags--;
}
insert:
/*
* Stick new segment in its place;
* check for complete reassembly.
*/
if (p == NULL) {
LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
} else {
LIST_INSERT_AFTER(p, ipqe, ipqe_q);
}
next = 0;
for (p = NULL, q = LIST_FIRST(&fp->ipq_fragq); q != NULL;
p = q, q = LIST_NEXT(q, ipqe_q)) {
if (ntohs(q->ipqe_ip->ip_off) != next)
return (0);
next += ntohs(q->ipqe_ip->ip_len);
}
if (p->ipqe_mff)
return (0);
/*
* Reassembly is complete. Check for a bogus message size and
* concatenate fragments.
*/
q = LIST_FIRST(&fp->ipq_fragq);
ip = q->ipqe_ip;
if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
ipstat_inc(ips_toolong);
ip_freef(fp);
return (0);
}
m = q->ipqe_m;
t = m->m_next;
m->m_next = 0;
m_cat(m, t);
nq = LIST_NEXT(q, ipqe_q);
pool_put(&ipqent_pool, q);
ip_frags--;
for (q = nq; q != NULL; q = nq) {
t = q->ipqe_m;
nq = LIST_NEXT(q, ipqe_q);
pool_put(&ipqent_pool, q);
ip_frags--;
m_removehdr(t);
m_cat(m, t);
}
/*
* Create header for new ip packet by
* modifying header of first packet;
* dequeue and discard fragment reassembly header.
* Make header visible.
*/
ip->ip_len = htons(next);
ip->ip_src = fp->ipq_src;
ip->ip_dst = fp->ipq_dst;
LIST_REMOVE(fp, ipq_q);
pool_put(&ipq_pool, fp);
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
m_calchdrlen(m);
return (m);
dropfrag:
ipstat_inc(ips_fragdropped);
m_freem(m);
pool_put(&ipqent_pool, ipqe);
ip_frags--;
return (NULL);
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
void
ip_freef(struct ipq *fp)
{
struct ipqent *q;
MUTEX_ASSERT_LOCKED(&ipq_mutex);
while ((q = LIST_FIRST(&fp->ipq_fragq)) != NULL) {
LIST_REMOVE(q, ipqe_q);
m_freem(q->ipqe_m);
pool_put(&ipqent_pool, q);
ip_frags--;
}
LIST_REMOVE(fp, ipq_q);
pool_put(&ipq_pool, fp);
}
/*
* IP timer processing;
* if a timer expires on a reassembly queue, discard it.
*/
void
ip_slowtimo(void)
{
struct ipq *fp, *nfp;
mtx_enter(&ipq_mutex);
LIST_FOREACH_SAFE(fp, &ipq, ipq_q, nfp) {
if (--fp->ipq_ttl == 0) {
ipstat_inc(ips_fragtimeout);
ip_freef(fp);
}