fe267a5590
Mainly focus on files that use BSD 2-Clause license, however the tool I was using misidentified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts. No functional change intended.
438 lines
12 KiB
C
438 lines
12 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 2003 Andre Oppermann, Internet Business Solutions AG
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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. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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/*
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* ip_fastforward gets its speed from processing the forwarded packet to
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* completion (if_output on the other side) without any queues or netisr's.
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* The receiving interface DMAs the packet into memory, the upper half of
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* driver calls ip_fastforward, we do our routing table lookup and directly
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* send it off to the outgoing interface, which DMAs the packet to the
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* network card. The only part of the packet we touch with the CPU is the
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* IP header (unless there are complex firewall rules touching other parts
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* of the packet, but that is up to you). We are essentially limited by bus
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* bandwidth and how fast the network card/driver can set up receives and
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* transmits.
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*
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* We handle basic errors, IP header errors, checksum errors,
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* destination unreachable, fragmentation and fragmentation needed and
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* report them via ICMP to the sender.
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*
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* Else if something is not pure IPv4 unicast forwarding we fall back to
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* the normal ip_input processing path. We should only be called from
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* interfaces connected to the outside world.
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*
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* Firewalling is fully supported including divert, ipfw fwd and ipfilter
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* ipnat and address rewrite.
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*
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* IPSEC is not supported if this host is a tunnel broker. IPSEC is
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* supported for connections to/from local host.
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*
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* We try to do the least expensive (in CPU ops) checks and operations
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* first to catch junk with as little overhead as possible.
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*
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* We take full advantage of hardware support for IP checksum and
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* fragmentation offloading.
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*
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* We don't do ICMP redirect in the fast forwarding path. I have had my own
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* cases where two core routers with Zebra routing suite would send millions
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* ICMP redirects to connected hosts if the destination router was not the
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* default gateway. In one case it was filling the routing table of a host
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* with approximately 300.000 cloned redirect entries until it ran out of
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* kernel memory. However the networking code proved very robust and it didn't
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* crash or fail in other ways.
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*/
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/*
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* Many thanks to Matt Thomas of NetBSD for basic structure of ip_flow.c which
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* is being followed here.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ipstealth.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.h>
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#include <sys/sdt.h>
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#include <sys/socket.h>
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#include <sys/sysctl.h>
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#include <net/pfil.h>
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#include <net/if.h>
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#include <net/if_types.h>
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#include <net/if_var.h>
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#include <net/if_dl.h>
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#include <net/route.h>
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#include <net/vnet.h>
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#include <netinet/in.h>
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#include <netinet/in_fib.h>
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#include <netinet/in_kdtrace.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_icmp.h>
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#include <netinet/ip_options.h>
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#include <machine/in_cksum.h>
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static int
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ip_findroute(struct nhop4_basic *pnh, struct in_addr dest, struct mbuf *m)
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{
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bzero(pnh, sizeof(*pnh));
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if (fib4_lookup_nh_basic(M_GETFIB(m), dest, 0, 0, pnh) != 0) {
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IPSTAT_INC(ips_noroute);
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IPSTAT_INC(ips_cantforward);
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icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
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return (EHOSTUNREACH);
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}
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/*
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* Drop blackholed traffic and directed broadcasts.
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*/
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if ((pnh->nh_flags & (NHF_BLACKHOLE | NHF_BROADCAST)) != 0) {
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IPSTAT_INC(ips_cantforward);
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m_freem(m);
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return (EHOSTUNREACH);
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}
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if (pnh->nh_flags & NHF_REJECT) {
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IPSTAT_INC(ips_cantforward);
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icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
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return (EHOSTUNREACH);
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}
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return (0);
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}
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/*
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* Try to forward a packet based on the destination address.
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* This is a fast path optimized for the plain forwarding case.
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* If the packet is handled (and consumed) here then we return NULL;
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* otherwise mbuf is returned and the packet should be delivered
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* to ip_input for full processing.
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*/
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struct mbuf *
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ip_tryforward(struct mbuf *m)
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{
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struct ip *ip;
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struct mbuf *m0 = NULL;
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struct nhop4_basic nh;
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struct sockaddr_in dst;
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struct in_addr odest, dest;
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uint16_t ip_len, ip_off;
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int error = 0;
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struct m_tag *fwd_tag = NULL;
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/*
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* Are we active and forwarding packets?
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*/
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M_ASSERTVALID(m);
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M_ASSERTPKTHDR(m);
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#ifdef ALTQ
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/*
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* Is packet dropped by traffic conditioner?
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*/
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if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
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goto drop;
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#endif
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/*
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* Only IP packets without options
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*/
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ip = mtod(m, struct ip *);
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if (ip->ip_hl != (sizeof(struct ip) >> 2)) {
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if (V_ip_doopts == 1)
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return m;
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else if (V_ip_doopts == 2) {
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icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB,
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0, 0);
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return NULL; /* mbuf already free'd */
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}
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/* else ignore IP options and continue */
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}
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/*
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* Only unicast IP, not from loopback, no L2 or IP broadcast,
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* no multicast, no INADDR_ANY
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*
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* XXX: Probably some of these checks could be direct drop
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* conditions. However it is not clear whether there are some
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* hacks or obscure behaviours which make it necessary to
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* let ip_input handle it. We play safe here and let ip_input
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* deal with it until it is proven that we can directly drop it.
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*/
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if ((m->m_flags & (M_BCAST|M_MCAST)) ||
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(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
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ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST ||
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ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST ||
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IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
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IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
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IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) ||
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IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) ||
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ip->ip_src.s_addr == INADDR_ANY ||
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ip->ip_dst.s_addr == INADDR_ANY )
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return m;
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/*
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* Is it for a local address on this host?
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*/
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if (in_localip(ip->ip_dst))
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return m;
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IPSTAT_INC(ips_total);
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/*
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* Step 3: incoming packet firewall processing
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*/
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odest.s_addr = dest.s_addr = ip->ip_dst.s_addr;
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/*
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* Run through list of ipfilter hooks for input packets
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*/
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if (!PFIL_HOOKED(&V_inet_pfil_hook))
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goto passin;
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if (pfil_run_hooks(
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&V_inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) ||
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m == NULL)
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goto drop;
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M_ASSERTVALID(m);
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M_ASSERTPKTHDR(m);
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ip = mtod(m, struct ip *); /* m may have changed by pfil hook */
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dest.s_addr = ip->ip_dst.s_addr;
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/*
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* Destination address changed?
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*/
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if (odest.s_addr != dest.s_addr) {
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/*
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* Is it now for a local address on this host?
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*/
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if (in_localip(dest))
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goto forwardlocal;
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/*
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* Go on with new destination address
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*/
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}
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if (m->m_flags & M_FASTFWD_OURS) {
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/*
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* ipfw changed it for a local address on this host.
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*/
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goto forwardlocal;
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}
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passin:
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/*
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* Step 4: decrement TTL and look up route
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*/
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/*
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* Check TTL
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*/
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#ifdef IPSTEALTH
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if (!V_ipstealth) {
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#endif
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if (ip->ip_ttl <= IPTTLDEC) {
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icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0);
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return NULL; /* mbuf already free'd */
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}
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/*
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* Decrement the TTL and incrementally change the IP header checksum.
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* Don't bother doing this with hw checksum offloading, it's faster
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* doing it right here.
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*/
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ip->ip_ttl -= IPTTLDEC;
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if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
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ip->ip_sum -= ~htons(IPTTLDEC << 8);
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else
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ip->ip_sum += htons(IPTTLDEC << 8);
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#ifdef IPSTEALTH
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}
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#endif
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/*
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* Find route to destination.
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*/
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if (ip_findroute(&nh, dest, m) != 0)
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return (NULL); /* icmp unreach already sent */
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/*
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* Step 5: outgoing firewall packet processing
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*/
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if (!PFIL_HOOKED(&V_inet_pfil_hook))
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goto passout;
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if (pfil_run_hooks(&V_inet_pfil_hook, &m, nh.nh_ifp, PFIL_OUT, NULL) ||
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m == NULL) {
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goto drop;
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}
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M_ASSERTVALID(m);
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M_ASSERTPKTHDR(m);
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ip = mtod(m, struct ip *);
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dest.s_addr = ip->ip_dst.s_addr;
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/*
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* Destination address changed?
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*/
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if (m->m_flags & M_IP_NEXTHOP)
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fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
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if (odest.s_addr != dest.s_addr || fwd_tag != NULL) {
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/*
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* Is it now for a local address on this host?
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*/
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if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) {
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forwardlocal:
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/*
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* Return packet for processing by ip_input().
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*/
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m->m_flags |= M_FASTFWD_OURS;
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return (m);
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}
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/*
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* Redo route lookup with new destination address
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*/
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if (fwd_tag) {
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dest.s_addr = ((struct sockaddr_in *)
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(fwd_tag + 1))->sin_addr.s_addr;
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m_tag_delete(m, fwd_tag);
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m->m_flags &= ~M_IP_NEXTHOP;
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}
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if (ip_findroute(&nh, dest, m) != 0)
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return (NULL); /* icmp unreach already sent */
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}
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passout:
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/*
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* Step 6: send off the packet
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*/
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ip_len = ntohs(ip->ip_len);
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ip_off = ntohs(ip->ip_off);
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bzero(&dst, sizeof(dst));
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dst.sin_family = AF_INET;
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dst.sin_len = sizeof(dst);
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dst.sin_addr = nh.nh_addr;
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/*
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* Check if packet fits MTU or if hardware will fragment for us
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*/
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if (ip_len <= nh.nh_mtu) {
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/*
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* Avoid confusing lower layers.
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*/
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m_clrprotoflags(m);
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/*
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* Send off the packet via outgoing interface
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*/
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IP_PROBE(send, NULL, NULL, ip, nh.nh_ifp, ip, NULL);
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error = (*nh.nh_ifp->if_output)(nh.nh_ifp, m,
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(struct sockaddr *)&dst, NULL);
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} else {
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/*
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* Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery
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*/
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if (ip_off & IP_DF) {
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IPSTAT_INC(ips_cantfrag);
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icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG,
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0, nh.nh_mtu);
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goto consumed;
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} else {
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/*
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* We have to fragment the packet
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*/
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m->m_pkthdr.csum_flags |= CSUM_IP;
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if (ip_fragment(ip, &m, nh.nh_mtu,
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nh.nh_ifp->if_hwassist) != 0)
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goto drop;
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KASSERT(m != NULL, ("null mbuf and no error"));
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/*
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* Send off the fragments via outgoing interface
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*/
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error = 0;
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do {
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m0 = m->m_nextpkt;
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m->m_nextpkt = NULL;
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/*
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* Avoid confusing lower layers.
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*/
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m_clrprotoflags(m);
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IP_PROBE(send, NULL, NULL,
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mtod(m, struct ip *), nh.nh_ifp,
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mtod(m, struct ip *), NULL);
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/* XXX: we can use cached route here */
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error = (*nh.nh_ifp->if_output)(nh.nh_ifp, m,
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(struct sockaddr *)&dst, NULL);
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if (error)
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break;
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} while ((m = m0) != NULL);
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if (error) {
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/* Reclaim remaining fragments */
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for (m = m0; m; m = m0) {
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m0 = m->m_nextpkt;
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m_freem(m);
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}
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} else
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IPSTAT_INC(ips_fragmented);
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}
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}
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if (error != 0)
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IPSTAT_INC(ips_odropped);
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else {
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IPSTAT_INC(ips_forward);
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IPSTAT_INC(ips_fastforward);
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}
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consumed:
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return NULL;
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drop:
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if (m)
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m_freem(m);
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return NULL;
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}
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