freebsd-dev/sys/netinet6/ip6_fastfwd.c

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/*-
* Copyright (c) 2014-2016 Andrey V. Elsukov <ae@FreeBSD.org>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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>
__FBSDID("$FreeBSD$");
#include "opt_inet6.h"
#include "opt_ipstealth.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/route.h>
#include <net/route/nhop.h>
#include <net/pfil.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_kdtrace.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet6/in6_var.h>
#include <netinet6/in6_fib.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
static int
ip6_findroute(struct nhop_object **pnh, const struct sockaddr_in6 *dst,
struct mbuf *m)
{
struct nhop_object *nh;
nh = fib6_lookup(M_GETFIB(m), &dst->sin6_addr,
dst->sin6_scope_id, NHR_NONE, m->m_pkthdr.flowid);
if (nh == NULL) {
IP6STAT_INC(ip6s_noroute);
IP6STAT_INC(ip6s_cantforward);
icmp6_error(m, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_NOROUTE, 0);
return (EHOSTUNREACH);
}
if (nh->nh_flags & NHF_BLACKHOLE) {
IP6STAT_INC(ip6s_cantforward);
m_freem(m);
return (EHOSTUNREACH);
}
if (nh->nh_flags & NHF_REJECT) {
IP6STAT_INC(ip6s_cantforward);
icmp6_error(m, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_REJECT, 0);
return (EHOSTUNREACH);
}
*pnh = nh;
return (0);
}
struct mbuf*
ip6_tryforward(struct mbuf *m)
{
struct sockaddr_in6 dst;
struct nhop_object *nh;
struct m_tag *fwd_tag;
struct ip6_hdr *ip6;
struct ifnet *rcvif;
uint32_t plen;
int error;
/*
* Fallback conditions to ip6_input for slow path processing.
*/
ip6 = mtod(m, struct ip6_hdr *);
if ((m->m_flags & (M_BCAST | M_MCAST)) != 0 ||
ip6->ip6_nxt == IPPROTO_HOPOPTS ||
IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst) ||
IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src) ||
IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) ||
in6_localip(&ip6->ip6_dst))
return (m);
/*
* Check that the amount of data in the buffers
* is as at least much as the IPv6 header would have us expect.
* Trim mbufs if longer than we expect.
* Drop packet if shorter than we expect.
*/
rcvif = m->m_pkthdr.rcvif;
plen = ntohs(ip6->ip6_plen);
if (plen == 0) {
/*
* Jumbograms must have hop-by-hop header and go via
* slow path.
*/
IP6STAT_INC(ip6s_badoptions);
goto dropin;
}
if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
IP6STAT_INC(ip6s_tooshort);
in6_ifstat_inc(rcvif, ifs6_in_truncated);
goto dropin;
}
if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
if (m->m_len == m->m_pkthdr.len) {
m->m_len = sizeof(struct ip6_hdr) + plen;
m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
} else
m_adj(m, sizeof(struct ip6_hdr) + plen -
m->m_pkthdr.len);
}
/*
* Hop limit.
*/
#ifdef IPSTEALTH
if (!V_ip6stealth)
#endif
if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
icmp6_error(m, ICMP6_TIME_EXCEEDED,
ICMP6_TIME_EXCEED_TRANSIT, 0);
m = NULL;
goto dropin;
}
bzero(&dst, sizeof(dst));
dst.sin6_family = AF_INET6;
dst.sin6_len = sizeof(dst);
dst.sin6_addr = ip6->ip6_dst;
/*
* Incoming packet firewall processing.
*/
New pfil(9) KPI together with newborn pfil API and control utility. The KPI have been reviewed and cleansed of features that were planned back 20 years ago and never implemented. The pfil(9) internals have been made opaque to protocols with only returned types and function declarations exposed. The KPI is made more strict, but at the same time more extensible, as kernel uses same command structures that userland ioctl uses. In nutshell [KA]PI is about declaring filtering points, declaring filters and linking and unlinking them together. New [KA]PI makes it possible to reconfigure pfil(9) configuration: change order of hooks, rehook filter from one filtering point to a different one, disconnect a hook on output leaving it on input only, prepend/append a filter to existing list of filters. Now it possible for a single packet filter to provide multiple rulesets that may be linked to different points. Think of per-interface ACLs in Cisco or Juniper. None of existing packet filters yet support that, however limited usage is already possible, e.g. default ruleset can be moved to single interface, as soon as interface would pride their filtering points. Another future feature is possiblity to create pfil heads, that provide not an mbuf pointer but just a memory pointer with length. That would allow filtering at very early stages of a packet lifecycle, e.g. when packet has just been received by a NIC and no mbuf was yet allocated. Differential Revision: https://reviews.freebsd.org/D18951
2019-01-31 23:01:03 +00:00
if (!PFIL_HOOKED_IN(V_inet6_pfil_head))
goto passin;
if (pfil_mbuf_in(V_inet6_pfil_head, &m, rcvif, NULL) !=
New pfil(9) KPI together with newborn pfil API and control utility. The KPI have been reviewed and cleansed of features that were planned back 20 years ago and never implemented. The pfil(9) internals have been made opaque to protocols with only returned types and function declarations exposed. The KPI is made more strict, but at the same time more extensible, as kernel uses same command structures that userland ioctl uses. In nutshell [KA]PI is about declaring filtering points, declaring filters and linking and unlinking them together. New [KA]PI makes it possible to reconfigure pfil(9) configuration: change order of hooks, rehook filter from one filtering point to a different one, disconnect a hook on output leaving it on input only, prepend/append a filter to existing list of filters. Now it possible for a single packet filter to provide multiple rulesets that may be linked to different points. Think of per-interface ACLs in Cisco or Juniper. None of existing packet filters yet support that, however limited usage is already possible, e.g. default ruleset can be moved to single interface, as soon as interface would pride their filtering points. Another future feature is possiblity to create pfil heads, that provide not an mbuf pointer but just a memory pointer with length. That would allow filtering at very early stages of a packet lifecycle, e.g. when packet has just been received by a NIC and no mbuf was yet allocated. Differential Revision: https://reviews.freebsd.org/D18951
2019-01-31 23:01:03 +00:00
PFIL_PASS)
goto dropin;
/*
* If packet filter sets the M_FASTFWD_OURS flag, this means
* that new destination or next hop is our local address.
* So, we can just go back to ip6_input.
* XXX: should we decrement ip6_hlim in such case?
*
* Also it can forward packet to another destination, e.g.
* M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf.
*/
if (m->m_flags & M_FASTFWD_OURS)
return (m);
ip6 = mtod(m, struct ip6_hdr *);
if ((m->m_flags & M_IP6_NEXTHOP) &&
(fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
/*
* Now we will find route to forwarded by pfil destination.
*/
bcopy((fwd_tag + 1), &dst, sizeof(dst));
m->m_flags &= ~M_IP6_NEXTHOP;
m_tag_delete(m, fwd_tag);
} else {
/* Update dst since pfil could change it */
dst.sin6_addr = ip6->ip6_dst;
}
passin:
/*
* Find route to destination.
*/
if (ip6_findroute(&nh, &dst, m) != 0) {
m = NULL;
in6_ifstat_inc(rcvif, ifs6_in_noroute);
goto dropin;
}
New pfil(9) KPI together with newborn pfil API and control utility. The KPI have been reviewed and cleansed of features that were planned back 20 years ago and never implemented. The pfil(9) internals have been made opaque to protocols with only returned types and function declarations exposed. The KPI is made more strict, but at the same time more extensible, as kernel uses same command structures that userland ioctl uses. In nutshell [KA]PI is about declaring filtering points, declaring filters and linking and unlinking them together. New [KA]PI makes it possible to reconfigure pfil(9) configuration: change order of hooks, rehook filter from one filtering point to a different one, disconnect a hook on output leaving it on input only, prepend/append a filter to existing list of filters. Now it possible for a single packet filter to provide multiple rulesets that may be linked to different points. Think of per-interface ACLs in Cisco or Juniper. None of existing packet filters yet support that, however limited usage is already possible, e.g. default ruleset can be moved to single interface, as soon as interface would pride their filtering points. Another future feature is possiblity to create pfil heads, that provide not an mbuf pointer but just a memory pointer with length. That would allow filtering at very early stages of a packet lifecycle, e.g. when packet has just been received by a NIC and no mbuf was yet allocated. Differential Revision: https://reviews.freebsd.org/D18951
2019-01-31 23:01:03 +00:00
if (!PFIL_HOOKED_OUT(V_inet6_pfil_head)) {
if (m->m_pkthdr.len > nh->nh_mtu) {
in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig);
icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu);
m = NULL;
goto dropout;
}
goto passout;
}
/*
* Outgoing packet firewall processing.
*/
if (pfil_mbuf_out(V_inet6_pfil_head, &m, nh->nh_ifp,
NULL) != PFIL_PASS)
goto dropout;
/*
* We used slow path processing for packets with scoped addresses.
* So, scope checks aren't needed here.
*/
if (m->m_pkthdr.len > nh->nh_mtu) {
in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig);
icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu);
m = NULL;
goto dropout;
}
/*
* If packet filter sets the M_FASTFWD_OURS flag, this means
* that new destination or next hop is our local address.
* So, we can just go back to ip6_input.
*
* Also it can forward packet to another destination, e.g.
* M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf.
*/
if (m->m_flags & M_FASTFWD_OURS) {
/*
* XXX: we did one hop and should decrement hop limit. But
* now we are the destination and just don't pay attention.
*/
return (m);
}
/*
* Again. A packet filter could change the destination address.
*/
ip6 = mtod(m, struct ip6_hdr *);
if (m->m_flags & M_IP6_NEXTHOP)
fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
else
fwd_tag = NULL;
if (fwd_tag != NULL ||
!IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &ip6->ip6_dst)) {
if (fwd_tag != NULL) {
bcopy((fwd_tag + 1), &dst, sizeof(dst));
m->m_flags &= ~M_IP6_NEXTHOP;
m_tag_delete(m, fwd_tag);
} else
dst.sin6_addr = ip6->ip6_dst;
/*
* Redo route lookup with new destination address
*/
if (ip6_findroute(&nh, &dst, m) != 0) {
m = NULL;
goto dropout;
}
}
passout:
#ifdef IPSTEALTH
if (!V_ip6stealth)
#endif
{
ip6->ip6_hlim -= IPV6_HLIMDEC;
}
m_clrprotoflags(m); /* Avoid confusing lower layers. */
IP_PROBE(send, NULL, NULL, ip6, nh->nh_ifp, NULL, ip6);
if (nh->nh_flags & NHF_GATEWAY)
dst.sin6_addr = nh->gw6_sa.sin6_addr;
error = (*nh->nh_ifp->if_output)(nh->nh_ifp, m,
(struct sockaddr *)&dst, NULL);
if (error != 0) {
in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard);
IP6STAT_INC(ip6s_cantforward);
} else {
in6_ifstat_inc(nh->nh_ifp, ifs6_out_forward);
IP6STAT_INC(ip6s_forward);
}
return (NULL);
dropin:
in6_ifstat_inc(rcvif, ifs6_in_discard);
goto drop;
dropout:
in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard);
drop:
if (m != NULL)
m_freem(m);
return (NULL);
}