480 lines
12 KiB
C
480 lines
12 KiB
C
/*-
|
|
* Copyright (c) 2003 Andre Oppermann, Internet Business Solutions AG
|
|
* 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. The name of the author may not be used to endorse or promote
|
|
* products derived from this software without specific prior written
|
|
* permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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_fastforward gets its speed from processing the forwarded packet to
|
|
* completion (if_output on the other side) without any queues or netisr's.
|
|
* The receiving interface DMAs the packet into memory, the upper half of
|
|
* driver calls ip_fastforward, we do our routing table lookup and directly
|
|
* send it off to the outgoing interface, which DMAs the packet to the
|
|
* network card. The only part of the packet we touch with the CPU is the
|
|
* IP header (unless there are complex firewall rules touching other parts
|
|
* of the packet, but that is up to you). We are essentially limited by bus
|
|
* bandwidth and how fast the network card/driver can set up receives and
|
|
* transmits.
|
|
*
|
|
* We handle basic errors, IP header errors, checksum errors,
|
|
* destination unreachable, fragmentation and fragmentation needed and
|
|
* report them via ICMP to the sender.
|
|
*
|
|
* Else if something is not pure IPv4 unicast forwarding we fall back to
|
|
* the normal ip_input processing path. We should only be called from
|
|
* interfaces connected to the outside world.
|
|
*
|
|
* Firewalling is fully supported including divert, ipfw fwd and ipfilter
|
|
* ipnat and address rewrite.
|
|
*
|
|
* IPSEC is not supported if this host is a tunnel broker. IPSEC is
|
|
* supported for connections to/from local host.
|
|
*
|
|
* We try to do the least expensive (in CPU ops) checks and operations
|
|
* first to catch junk with as little overhead as possible.
|
|
*
|
|
* We take full advantage of hardware support for IP checksum and
|
|
* fragmentation offloading.
|
|
*
|
|
* We don't do ICMP redirect in the fast forwarding path. I have had my own
|
|
* cases where two core routers with Zebra routing suite would send millions
|
|
* ICMP redirects to connected hosts if the destination router was not the
|
|
* default gateway. In one case it was filling the routing table of a host
|
|
* with approximately 300.000 cloned redirect entries until it ran out of
|
|
* kernel memory. However the networking code proved very robust and it didn't
|
|
* crash or fail in other ways.
|
|
*/
|
|
|
|
/*
|
|
* Many thanks to Matt Thomas of NetBSD for basic structure of ip_flow.c which
|
|
* is being followed here.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include "opt_ipstealth.h"
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/mbuf.h>
|
|
#include <sys/protosw.h>
|
|
#include <sys/sdt.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/sysctl.h>
|
|
|
|
#include <net/pfil.h>
|
|
#include <net/if.h>
|
|
#include <net/if_types.h>
|
|
#include <net/if_var.h>
|
|
#include <net/if_dl.h>
|
|
#include <net/route.h>
|
|
#include <net/vnet.h>
|
|
|
|
#include <netinet/in.h>
|
|
#include <netinet/in_kdtrace.h>
|
|
#include <netinet/in_systm.h>
|
|
#include <netinet/in_var.h>
|
|
#include <netinet/ip.h>
|
|
#include <netinet/ip_var.h>
|
|
#include <netinet/ip_icmp.h>
|
|
#include <netinet/ip_options.h>
|
|
|
|
#include <machine/in_cksum.h>
|
|
|
|
static struct sockaddr_in *
|
|
ip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m)
|
|
{
|
|
struct sockaddr_in *dst;
|
|
struct rtentry *rt;
|
|
|
|
/*
|
|
* Find route to destination.
|
|
*/
|
|
bzero(ro, sizeof(*ro));
|
|
dst = (struct sockaddr_in *)&ro->ro_dst;
|
|
dst->sin_family = AF_INET;
|
|
dst->sin_len = sizeof(*dst);
|
|
dst->sin_addr.s_addr = dest.s_addr;
|
|
in_rtalloc_ign(ro, 0, M_GETFIB(m));
|
|
|
|
/*
|
|
* Route there and interface still up?
|
|
*/
|
|
rt = ro->ro_rt;
|
|
if (rt && (rt->rt_flags & RTF_UP) &&
|
|
(rt->rt_ifp->if_flags & IFF_UP) &&
|
|
(rt->rt_ifp->if_drv_flags & IFF_DRV_RUNNING)) {
|
|
if (rt->rt_flags & RTF_GATEWAY)
|
|
dst = (struct sockaddr_in *)rt->rt_gateway;
|
|
} else {
|
|
IPSTAT_INC(ips_noroute);
|
|
IPSTAT_INC(ips_cantforward);
|
|
if (rt)
|
|
RTFREE(rt);
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
|
|
return NULL;
|
|
}
|
|
return dst;
|
|
}
|
|
|
|
/*
|
|
* Try to forward a packet based on the destination address.
|
|
* This is a fast path optimized for the plain forwarding case.
|
|
* If the packet is handled (and consumed) here then we return NULL;
|
|
* otherwise mbuf is returned and the packet should be delivered
|
|
* to ip_input for full processing.
|
|
*/
|
|
struct mbuf *
|
|
ip_tryforward(struct mbuf *m)
|
|
{
|
|
struct ip *ip;
|
|
struct mbuf *m0 = NULL;
|
|
struct route ro;
|
|
struct sockaddr_in *dst = NULL;
|
|
struct ifnet *ifp;
|
|
struct in_addr odest, dest;
|
|
uint16_t ip_len, ip_off;
|
|
int error = 0;
|
|
int mtu;
|
|
struct m_tag *fwd_tag = NULL;
|
|
|
|
/*
|
|
* Are we active and forwarding packets?
|
|
*/
|
|
|
|
M_ASSERTVALID(m);
|
|
M_ASSERTPKTHDR(m);
|
|
|
|
bzero(&ro, sizeof(ro));
|
|
|
|
|
|
#ifdef ALTQ
|
|
/*
|
|
* Is packet dropped by traffic conditioner?
|
|
*/
|
|
if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
|
|
goto drop;
|
|
#endif
|
|
|
|
/*
|
|
* Only IP packets without options
|
|
*/
|
|
ip = mtod(m, struct ip *);
|
|
|
|
if (ip->ip_hl != (sizeof(struct ip) >> 2)) {
|
|
if (V_ip_doopts == 1)
|
|
return m;
|
|
else if (V_ip_doopts == 2) {
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB,
|
|
0, 0);
|
|
return NULL; /* mbuf already free'd */
|
|
}
|
|
/* else ignore IP options and continue */
|
|
}
|
|
|
|
/*
|
|
* Only unicast IP, not from loopback, no L2 or IP broadcast,
|
|
* no multicast, no INADDR_ANY
|
|
*
|
|
* XXX: Probably some of these checks could be direct drop
|
|
* conditions. However it is not clear whether there are some
|
|
* hacks or obscure behaviours which make it necessary to
|
|
* let ip_input handle it. We play safe here and let ip_input
|
|
* deal with it until it is proven that we can directly drop it.
|
|
*/
|
|
if ((m->m_flags & (M_BCAST|M_MCAST)) ||
|
|
(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
|
|
ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST ||
|
|
ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST ||
|
|
IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
|
|
IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
|
|
IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) ||
|
|
IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) ||
|
|
ip->ip_src.s_addr == INADDR_ANY ||
|
|
ip->ip_dst.s_addr == INADDR_ANY )
|
|
return m;
|
|
|
|
/*
|
|
* Is it for a local address on this host?
|
|
*/
|
|
if (in_localip(ip->ip_dst))
|
|
return m;
|
|
|
|
IPSTAT_INC(ips_total);
|
|
|
|
/*
|
|
* Step 3: incoming packet firewall processing
|
|
*/
|
|
|
|
odest.s_addr = dest.s_addr = ip->ip_dst.s_addr;
|
|
|
|
/*
|
|
* Run through list of ipfilter hooks for input packets
|
|
*/
|
|
if (!PFIL_HOOKED(&V_inet_pfil_hook))
|
|
goto passin;
|
|
|
|
if (pfil_run_hooks(
|
|
&V_inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) ||
|
|
m == NULL)
|
|
goto drop;
|
|
|
|
M_ASSERTVALID(m);
|
|
M_ASSERTPKTHDR(m);
|
|
|
|
ip = mtod(m, struct ip *); /* m may have changed by pfil hook */
|
|
dest.s_addr = ip->ip_dst.s_addr;
|
|
|
|
/*
|
|
* Destination address changed?
|
|
*/
|
|
if (odest.s_addr != dest.s_addr) {
|
|
/*
|
|
* Is it now for a local address on this host?
|
|
*/
|
|
if (in_localip(dest))
|
|
goto forwardlocal;
|
|
/*
|
|
* Go on with new destination address
|
|
*/
|
|
}
|
|
|
|
if (m->m_flags & M_FASTFWD_OURS) {
|
|
/*
|
|
* ipfw changed it for a local address on this host.
|
|
*/
|
|
goto forwardlocal;
|
|
}
|
|
|
|
passin:
|
|
/*
|
|
* Step 4: decrement TTL and look up route
|
|
*/
|
|
|
|
/*
|
|
* Check TTL
|
|
*/
|
|
#ifdef IPSTEALTH
|
|
if (!V_ipstealth) {
|
|
#endif
|
|
if (ip->ip_ttl <= IPTTLDEC) {
|
|
icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0);
|
|
return NULL; /* mbuf already free'd */
|
|
}
|
|
|
|
/*
|
|
* Decrement the TTL and incrementally change the IP header checksum.
|
|
* Don't bother doing this with hw checksum offloading, it's faster
|
|
* doing it right here.
|
|
*/
|
|
ip->ip_ttl -= IPTTLDEC;
|
|
if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
|
|
ip->ip_sum -= ~htons(IPTTLDEC << 8);
|
|
else
|
|
ip->ip_sum += htons(IPTTLDEC << 8);
|
|
#ifdef IPSTEALTH
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Find route to destination.
|
|
*/
|
|
if ((dst = ip_findroute(&ro, dest, m)) == NULL)
|
|
return NULL; /* icmp unreach already sent */
|
|
ifp = ro.ro_rt->rt_ifp;
|
|
|
|
/*
|
|
* Immediately drop blackholed traffic, and directed broadcasts
|
|
* for either the all-ones or all-zero subnet addresses on
|
|
* locally attached networks.
|
|
*/
|
|
if ((ro.ro_rt->rt_flags & (RTF_BLACKHOLE|RTF_BROADCAST)) != 0)
|
|
goto drop;
|
|
|
|
/*
|
|
* Step 5: outgoing firewall packet processing
|
|
*/
|
|
|
|
/*
|
|
* Run through list of hooks for output packets.
|
|
*/
|
|
if (!PFIL_HOOKED(&V_inet_pfil_hook))
|
|
goto passout;
|
|
|
|
if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, NULL) || m == NULL) {
|
|
goto drop;
|
|
}
|
|
|
|
M_ASSERTVALID(m);
|
|
M_ASSERTPKTHDR(m);
|
|
|
|
ip = mtod(m, struct ip *);
|
|
dest.s_addr = ip->ip_dst.s_addr;
|
|
|
|
/*
|
|
* Destination address changed?
|
|
*/
|
|
if (m->m_flags & M_IP_NEXTHOP)
|
|
fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
|
|
if (odest.s_addr != dest.s_addr || fwd_tag != NULL) {
|
|
/*
|
|
* Is it now for a local address on this host?
|
|
*/
|
|
if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) {
|
|
forwardlocal:
|
|
/*
|
|
* Return packet for processing by ip_input().
|
|
*/
|
|
m->m_flags |= M_FASTFWD_OURS;
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
return m;
|
|
}
|
|
/*
|
|
* Redo route lookup with new destination address
|
|
*/
|
|
if (fwd_tag) {
|
|
dest.s_addr = ((struct sockaddr_in *)
|
|
(fwd_tag + 1))->sin_addr.s_addr;
|
|
m_tag_delete(m, fwd_tag);
|
|
m->m_flags &= ~M_IP_NEXTHOP;
|
|
}
|
|
RTFREE(ro.ro_rt);
|
|
if ((dst = ip_findroute(&ro, dest, m)) == NULL)
|
|
return NULL; /* icmp unreach already sent */
|
|
ifp = ro.ro_rt->rt_ifp;
|
|
}
|
|
|
|
passout:
|
|
/*
|
|
* Step 6: send off the packet
|
|
*/
|
|
ip_len = ntohs(ip->ip_len);
|
|
ip_off = ntohs(ip->ip_off);
|
|
|
|
/*
|
|
* Check if route is dampned (when ARP is unable to resolve)
|
|
*/
|
|
if ((ro.ro_rt->rt_flags & RTF_REJECT) &&
|
|
(ro.ro_rt->rt_expire == 0 || time_uptime < ro.ro_rt->rt_expire)) {
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
|
|
goto consumed;
|
|
}
|
|
|
|
/*
|
|
* Check if media link state of interface is not down
|
|
*/
|
|
if (ifp->if_link_state == LINK_STATE_DOWN) {
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
|
|
goto consumed;
|
|
}
|
|
|
|
/*
|
|
* Check if packet fits MTU or if hardware will fragment for us
|
|
*/
|
|
if (ro.ro_rt->rt_mtu)
|
|
mtu = min(ro.ro_rt->rt_mtu, ifp->if_mtu);
|
|
else
|
|
mtu = ifp->if_mtu;
|
|
|
|
if (ip_len <= mtu) {
|
|
/*
|
|
* Avoid confusing lower layers.
|
|
*/
|
|
m_clrprotoflags(m);
|
|
/*
|
|
* Send off the packet via outgoing interface
|
|
*/
|
|
IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
|
|
error = (*ifp->if_output)(ifp, m,
|
|
(struct sockaddr *)dst, &ro);
|
|
} else {
|
|
/*
|
|
* Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery
|
|
*/
|
|
if (ip_off & IP_DF) {
|
|
IPSTAT_INC(ips_cantfrag);
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG,
|
|
0, mtu);
|
|
goto consumed;
|
|
} else {
|
|
/*
|
|
* We have to fragment the packet
|
|
*/
|
|
m->m_pkthdr.csum_flags |= CSUM_IP;
|
|
if (ip_fragment(ip, &m, mtu, ifp->if_hwassist))
|
|
goto drop;
|
|
KASSERT(m != NULL, ("null mbuf and no error"));
|
|
/*
|
|
* Send off the fragments via outgoing interface
|
|
*/
|
|
error = 0;
|
|
do {
|
|
m0 = m->m_nextpkt;
|
|
m->m_nextpkt = NULL;
|
|
/*
|
|
* Avoid confusing lower layers.
|
|
*/
|
|
m_clrprotoflags(m);
|
|
|
|
IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
|
|
error = (*ifp->if_output)(ifp, m,
|
|
(struct sockaddr *)dst, &ro);
|
|
if (error)
|
|
break;
|
|
} while ((m = m0) != NULL);
|
|
if (error) {
|
|
/* Reclaim remaining fragments */
|
|
for (m = m0; m; m = m0) {
|
|
m0 = m->m_nextpkt;
|
|
m_freem(m);
|
|
}
|
|
} else
|
|
IPSTAT_INC(ips_fragmented);
|
|
}
|
|
}
|
|
|
|
if (error != 0)
|
|
IPSTAT_INC(ips_odropped);
|
|
else {
|
|
counter_u64_add(ro.ro_rt->rt_pksent, 1);
|
|
IPSTAT_INC(ips_forward);
|
|
IPSTAT_INC(ips_fastforward);
|
|
}
|
|
consumed:
|
|
RTFREE(ro.ro_rt);
|
|
return NULL;
|
|
drop:
|
|
if (m)
|
|
m_freem(m);
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
return NULL;
|
|
}
|