ip6_fastfwd.c

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    1 /*-
    2  * Copyright (c) 2014-2016 Andrey V. Elsukov <ae@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  *
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/11.1/sys/netinet6/ip6_fastfwd.c 311681 2017-01-08 13:31:24Z ae $");
   29 
   30 #include "opt_inet6.h"
   31 #include "opt_ipstealth.h"
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/mbuf.h>
   36 #include <sys/socket.h>
   37 #include <sys/kernel.h>
   38 #include <sys/sysctl.h>
   39 
   40 #include <net/if.h>
   41 #include <net/if_var.h>
   42 #include <net/route.h>
   43 #include <net/pfil.h>
   44 #include <net/vnet.h>
   45 
   46 #include <netinet/in.h>
   47 #include <netinet/in_kdtrace.h>
   48 #include <netinet/in_var.h>
   49 #include <netinet/ip_var.h>
   50 #include <netinet/ip6.h>
   51 #include <netinet/icmp6.h>
   52 #include <netinet6/in6_var.h>
   53 #include <netinet6/in6_fib.h>
   54 #include <netinet6/ip6_var.h>
   55 #include <netinet6/nd6.h>
   56 
   57 static int
   58 ip6_findroute(struct nhop6_basic *pnh, const struct sockaddr_in6 *dst,
   59     struct mbuf *m)
   60 {
   61 
   62         if (fib6_lookup_nh_basic(M_GETFIB(m), &dst->sin6_addr,
   63             dst->sin6_scope_id, 0, dst->sin6_flowinfo, pnh) != 0) {
   64                 IP6STAT_INC(ip6s_noroute);
   65                 IP6STAT_INC(ip6s_cantforward);
   66                 icmp6_error(m, ICMP6_DST_UNREACH,
   67                     ICMP6_DST_UNREACH_NOROUTE, 0);
   68                 return (EHOSTUNREACH);
   69         }
   70         if (pnh->nh_flags & NHF_BLACKHOLE) {
   71                 IP6STAT_INC(ip6s_cantforward);
   72                 m_freem(m);
   73                 return (EHOSTUNREACH);
   74         }
   75 
   76         if (pnh->nh_flags & NHF_REJECT) {
   77                 IP6STAT_INC(ip6s_cantforward);
   78                 icmp6_error(m, ICMP6_DST_UNREACH,
   79                     ICMP6_DST_UNREACH_REJECT, 0);
   80                 return (EHOSTUNREACH);
   81         }
   82         return (0);
   83 }
   84 
   85 struct mbuf*
   86 ip6_tryforward(struct mbuf *m)
   87 {
   88         struct sockaddr_in6 dst;
   89         struct nhop6_basic nh;
   90         struct m_tag *fwd_tag;
   91         struct ip6_hdr *ip6;
   92         struct ifnet *rcvif;
   93         uint32_t plen;
   94         int error;
   95 
   96         /*
   97          * Fallback conditions to ip6_input for slow path processing.
   98          */
   99         ip6 = mtod(m, struct ip6_hdr *);
  100         if (ip6->ip6_nxt == IPPROTO_HOPOPTS ||
  101             IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
  102             IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_dst) ||
  103             IN6_IS_ADDR_LINKLOCAL(&ip6->ip6_src) ||
  104             IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) ||
  105             in6_localip(&ip6->ip6_dst))
  106                 return (m);
  107         /*
  108          * Check that the amount of data in the buffers
  109          * is as at least much as the IPv6 header would have us expect.
  110          * Trim mbufs if longer than we expect.
  111          * Drop packet if shorter than we expect.
  112          */
  113         rcvif = m->m_pkthdr.rcvif;
  114         plen = ntohs(ip6->ip6_plen);
  115         if (plen == 0) {
  116                 /*
  117                  * Jumbograms must have hop-by-hop header and go via
  118                  * slow path.
  119                  */
  120                 IP6STAT_INC(ip6s_badoptions);
  121                 goto dropin;
  122         }
  123         if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
  124                 IP6STAT_INC(ip6s_tooshort);
  125                 in6_ifstat_inc(rcvif, ifs6_in_truncated);
  126                 goto dropin;
  127         }
  128         if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
  129                 if (m->m_len == m->m_pkthdr.len) {
  130                         m->m_len = sizeof(struct ip6_hdr) + plen;
  131                         m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
  132                 } else
  133                         m_adj(m, sizeof(struct ip6_hdr) + plen -
  134                             m->m_pkthdr.len);
  135         }
  136 
  137         /*
  138          * Hop limit.
  139          */
  140 #ifdef IPSTEALTH
  141         if (!V_ip6stealth)
  142 #endif
  143         if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
  144                 icmp6_error(m, ICMP6_TIME_EXCEEDED,
  145                     ICMP6_TIME_EXCEED_TRANSIT, 0);
  146                 m = NULL;
  147                 goto dropin;
  148         }
  149 
  150         bzero(&dst, sizeof(dst));
  151         dst.sin6_family = AF_INET6;
  152         dst.sin6_len = sizeof(dst);
  153         dst.sin6_addr = ip6->ip6_dst;
  154 
  155         /*
  156          * Incoming packet firewall processing.
  157          */
  158         if (!PFIL_HOOKED(&V_inet6_pfil_hook))
  159                 goto passin;
  160         if (pfil_run_hooks(&V_inet6_pfil_hook, &m, rcvif, PFIL_IN,
  161             NULL) != 0 || m == NULL)
  162                 goto dropin;
  163         /*
  164          * If packet filter sets the M_FASTFWD_OURS flag, this means
  165          * that new destination or next hop is our local address.
  166          * So, we can just go back to ip6_input.
  167          * XXX: should we decrement ip6_hlim in such case?
  168          *
  169          * Also it can forward packet to another destination, e.g.
  170          * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf.
  171          */
  172         if (m->m_flags & M_FASTFWD_OURS)
  173                 return (m);
  174 
  175         ip6 = mtod(m, struct ip6_hdr *);
  176         if ((m->m_flags & M_IP6_NEXTHOP) &&
  177             (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
  178                 /*
  179                  * Now we will find route to forwarded by pfil destination.
  180                  */
  181                 bcopy((fwd_tag + 1), &dst, sizeof(dst));
  182                 m->m_flags &= ~M_IP6_NEXTHOP;
  183                 m_tag_delete(m, fwd_tag);
  184         } else {
  185                 /* Update dst since pfil could change it */
  186                 dst.sin6_addr = ip6->ip6_dst;
  187         }
  188 passin:
  189         /*
  190          * Find route to destination.
  191          */
  192         if (ip6_findroute(&nh, &dst, m) != 0) {
  193                 m = NULL;
  194                 in6_ifstat_inc(rcvif, ifs6_in_noroute);
  195                 goto dropin;
  196         }
  197         /*
  198          * We used slow path processing for packets with scoped addresses.
  199          * So, scope checks aren't needed here.
  200          */
  201         if (m->m_pkthdr.len > nh.nh_mtu) {
  202                 in6_ifstat_inc(nh.nh_ifp, ifs6_in_toobig);
  203                 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, nh.nh_mtu);
  204                 m = NULL;
  205                 goto dropout;
  206         }
  207 
  208         /*
  209          * Outgoing packet firewall processing.
  210          */
  211         if (!PFIL_HOOKED(&V_inet6_pfil_hook))
  212                 goto passout;
  213         if (pfil_run_hooks(&V_inet6_pfil_hook, &m, nh.nh_ifp, PFIL_OUT,
  214             NULL) != 0 || m == NULL)
  215                 goto dropout;
  216         /*
  217          * If packet filter sets the M_FASTFWD_OURS flag, this means
  218          * that new destination or next hop is our local address.
  219          * So, we can just go back to ip6_input.
  220          *
  221          * Also it can forward packet to another destination, e.g.
  222          * M_IP6_NEXTHOP flag is set and fwd_tag is attached to mbuf.
  223          */
  224         if (m->m_flags & M_FASTFWD_OURS) {
  225                 /*
  226                  * XXX: we did one hop and should decrement hop limit. But
  227                  * now we are the destination and just don't pay attention.
  228                  */
  229                 return (m);
  230         }
  231         /*
  232          * Again. A packet filter could change the destination address.
  233          */
  234         ip6 = mtod(m, struct ip6_hdr *);
  235         if (m->m_flags & M_IP6_NEXTHOP)
  236                 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
  237         else
  238                 fwd_tag = NULL;
  239 
  240         if (fwd_tag != NULL ||
  241             !IN6_ARE_ADDR_EQUAL(&dst.sin6_addr, &ip6->ip6_dst)) {
  242                 if (fwd_tag != NULL) {
  243                         bcopy((fwd_tag + 1), &dst, sizeof(dst));
  244                         m->m_flags &= ~M_IP6_NEXTHOP;
  245                         m_tag_delete(m, fwd_tag);
  246                 } else
  247                         dst.sin6_addr = ip6->ip6_dst;
  248                 /*
  249                  * Redo route lookup with new destination address
  250                  */
  251                 if (ip6_findroute(&nh, &dst, m) != 0) {
  252                         m = NULL;
  253                         goto dropout;
  254                 }
  255         }
  256 passout:
  257 #ifdef IPSTEALTH
  258         if (!V_ip6stealth)
  259 #endif
  260         {
  261                 ip6->ip6_hlim -= IPV6_HLIMDEC;
  262         }
  263 
  264         m_clrprotoflags(m);     /* Avoid confusing lower layers. */
  265         IP_PROBE(send, NULL, NULL, ip6, nh.nh_ifp, NULL, ip6);
  266 
  267         /*
  268          * XXX: we need to use destination address with embedded scope
  269          * zone id, because LLTABLE uses such form of addresses for lookup.
  270          */
  271         dst.sin6_addr = nh.nh_addr;
  272         if (IN6_IS_SCOPE_LINKLOCAL(&dst.sin6_addr))
  273                 dst.sin6_addr.s6_addr16[1] = htons(nh.nh_ifp->if_index & 0xffff);
  274 
  275         error = (*nh.nh_ifp->if_output)(nh.nh_ifp, m,
  276             (struct sockaddr *)&dst, NULL);
  277         if (error != 0) {
  278                 in6_ifstat_inc(nh.nh_ifp, ifs6_out_discard);
  279                 IP6STAT_INC(ip6s_cantforward);
  280         } else {
  281                 in6_ifstat_inc(nh.nh_ifp, ifs6_out_forward);
  282                 IP6STAT_INC(ip6s_forward);
  283         }
  284         return (NULL);
  285 dropin:
  286         in6_ifstat_inc(rcvif, ifs6_in_discard);
  287         goto drop;
  288 dropout:
  289         in6_ifstat_inc(nh.nh_ifp, ifs6_out_discard);
  290 drop:
  291         if (m != NULL)
  292                 m_freem(m);
  293         return (NULL);
  294 }
  295
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/ip6_fastfwd.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet6/ip6_fastfwd.c
