The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_gre.c

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    1 /*      $NetBSD: ip_gre.c,v 1.29 2003/09/05 23:02:43 itojun Exp $ */
    2 
    3 /*-
    4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Heiko W.Rupp <hwr@pilhuhn.de>
    9  *
   10  * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   23  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   31  * POSSIBILITY OF SUCH DAMAGE.
   32  */
   33 
   34 /*
   35  * deencapsulate tunneled packets and send them on
   36  * output half is in net/if_gre.[ch]
   37  * This currently handles IPPROTO_GRE, IPPROTO_MOBILE
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: releng/9.2/sys/netinet/ip_gre.c 252023 2013-06-20 07:30:13Z hrs $");
   42 
   43 #include "opt_inet.h"
   44 #include "opt_atalk.h"
   45 #include "opt_inet6.h"
   46 
   47 #include <sys/param.h>
   48 #include <sys/systm.h>
   49 #include <sys/mbuf.h>
   50 #include <sys/socket.h>
   51 #include <sys/socketvar.h>
   52 #include <sys/protosw.h>
   53 #include <sys/errno.h>
   54 #include <sys/time.h>
   55 #include <sys/kernel.h>
   56 #include <sys/syslog.h>
   57 #include <net/bpf.h>
   58 #include <net/ethernet.h>
   59 #include <net/if.h>
   60 #include <net/netisr.h>
   61 #include <net/route.h>
   62 #include <net/raw_cb.h>
   63 
   64 #ifdef INET
   65 #include <netinet/in.h>
   66 #include <netinet/in_var.h>
   67 #include <netinet/in_systm.h>
   68 #include <netinet/ip.h>
   69 #include <netinet/ip_var.h>
   70 #include <netinet/ip_gre.h>
   71 #include <machine/in_cksum.h>
   72 #else
   73 #error ip_gre input without IP?
   74 #endif
   75 
   76 #ifdef NETATALK
   77 #include <netatalk/at.h>
   78 #include <netatalk/at_var.h>
   79 #include <netatalk/at_extern.h>
   80 #endif
   81 
   82 /* Needs IP headers. */
   83 #include <net/if_gre.h>
   84 
   85 #include <machine/stdarg.h>
   86 
   87 #if 1
   88 void gre_inet_ntoa(struct in_addr in);  /* XXX */
   89 #endif
   90 
   91 static struct gre_softc *gre_lookup(struct mbuf *, u_int8_t);
   92 
   93 static struct mbuf *gre_input2(struct mbuf *, int, u_char);
   94 
   95 /*
   96  * De-encapsulate a packet and feed it back through ip input (this
   97  * routine is called whenever IP gets a packet with proto type
   98  * IPPROTO_GRE and a local destination address).
   99  * This really is simple
  100  */
  101 void
  102 gre_input(struct mbuf *m, int off)
  103 {
  104         int proto;
  105 
  106         proto = (mtod(m, struct ip *))->ip_p;
  107 
  108         m = gre_input2(m, off, proto);
  109 
  110         /*
  111          * If no matching tunnel that is up is found. We inject
  112          * the mbuf to raw ip socket to see if anyone picks it up.
  113          */
  114         if (m != NULL)
  115                 rip_input(m, off);
  116 }
  117 
  118 /*
  119  * Decapsulate. Does the real work and is called from gre_input()
  120  * (above). Returns an mbuf back if packet is not yet processed,
  121  * and NULL if it needs no further processing. proto is the protocol
  122  * number of the "calling" foo_input() routine.
  123  */
  124 static struct mbuf *
  125 gre_input2(struct mbuf *m ,int hlen, u_char proto)
  126 {
  127         struct greip *gip;
  128         int isr;
  129         struct gre_softc *sc;
  130         u_int16_t flags;
  131         u_int32_t af;
  132 
  133         if ((sc = gre_lookup(m, proto)) == NULL) {
  134                 /* No matching tunnel or tunnel is down. */
  135                 return (m);
  136         }
  137 
  138         if (m->m_len < sizeof(*gip)) {
  139                 m = m_pullup(m, sizeof(*gip));
  140                 if (m == NULL)
  141                         return (NULL);
  142         }
  143         gip = mtod(m, struct greip *);
  144 
  145         GRE2IFP(sc)->if_ipackets++;
  146         GRE2IFP(sc)->if_ibytes += m->m_pkthdr.len;
  147 
  148         switch (proto) {
  149         case IPPROTO_GRE:
  150                 hlen += sizeof(struct gre_h);
  151 
  152                 /* process GRE flags as packet can be of variable len */
  153                 flags = ntohs(gip->gi_flags);
  154 
  155                 /* Checksum & Offset are present */
  156                 if ((flags & GRE_CP) | (flags & GRE_RP))
  157                         hlen += 4;
  158                 /* We don't support routing fields (variable length) */
  159                 if (flags & GRE_RP)
  160                         return (m);
  161                 if (flags & GRE_KP)
  162                         hlen += 4;
  163                 if (flags & GRE_SP)
  164                         hlen += 4;
  165 
  166                 switch (ntohs(gip->gi_ptype)) { /* ethertypes */
  167                 case WCCP_PROTOCOL_TYPE:
  168                         if (sc->wccp_ver == WCCP_V2)
  169                                 hlen += 4;
  170                         /* FALLTHROUGH */
  171                 case ETHERTYPE_IP:      /* shouldn't need a schednetisr(), */
  172                         isr = NETISR_IP;/* as we are in ip_input */
  173                         af = AF_INET;
  174                         break;
  175 #ifdef INET6
  176                 case ETHERTYPE_IPV6:
  177                         isr = NETISR_IPV6;
  178                         af = AF_INET6;
  179                         break;
  180 #endif
  181 #ifdef NETATALK
  182                 case ETHERTYPE_ATALK:
  183                         isr = NETISR_ATALK1;
  184                         af = AF_APPLETALK;
  185                         break;
  186 #endif
  187                 default:
  188                         /* Others not yet supported. */
  189                         return (m);
  190                 }
  191                 break;
  192         default:
  193                 /* Others not yet supported. */
  194                 return (m);
  195         }
  196 
  197         if (hlen > m->m_pkthdr.len) {
  198                 m_freem(m);
  199                 return (NULL);
  200         }
  201         /* Unlike NetBSD, in FreeBSD m_adj() adjusts m->m_pkthdr.len as well */
  202         m_adj(m, hlen);
  203 
  204         if (bpf_peers_present(GRE2IFP(sc)->if_bpf)) {
  205                 bpf_mtap2(GRE2IFP(sc)->if_bpf, &af, sizeof(af), m);
  206         }
  207 
  208         if ((GRE2IFP(sc)->if_flags & IFF_MONITOR) != 0) {
  209                 m_freem(m);
  210                 return(NULL);
  211         }
  212 
  213         m->m_pkthdr.rcvif = GRE2IFP(sc);
  214 
  215         netisr_queue(isr, m);
  216 
  217         /* Packet is done, no further processing needed. */
  218         return (NULL);
  219 }
  220 
  221 /*
  222  * input routine for IPPRPOTO_MOBILE
  223  * This is a little bit diffrent from the other modes, as the
  224  * encapsulating header was not prepended, but instead inserted
  225  * between IP header and payload
  226  */
  227 
  228 void
  229 gre_mobile_input(struct mbuf *m, int hlen)
  230 {
  231         struct ip *ip;
  232         struct mobip_h *mip;
  233         struct gre_softc *sc;
  234         int msiz;
  235 
  236         if ((sc = gre_lookup(m, IPPROTO_MOBILE)) == NULL) {
  237                 /* No matching tunnel or tunnel is down. */
  238                 m_freem(m);
  239                 return;
  240         }
  241 
  242         if (m->m_len < sizeof(*mip)) {
  243                 m = m_pullup(m, sizeof(*mip));
  244                 if (m == NULL)
  245                         return;
  246         }
  247         ip = mtod(m, struct ip *);
  248         mip = mtod(m, struct mobip_h *);
  249 
  250         GRE2IFP(sc)->if_ipackets++;
  251         GRE2IFP(sc)->if_ibytes += m->m_pkthdr.len;
  252 
  253         if (ntohs(mip->mh.proto) & MOB_H_SBIT) {
  254                 msiz = MOB_H_SIZ_L;
  255                 mip->mi.ip_src.s_addr = mip->mh.osrc;
  256         } else
  257                 msiz = MOB_H_SIZ_S;
  258 
  259         if (m->m_len < (ip->ip_hl << 2) + msiz) {
  260                 m = m_pullup(m, (ip->ip_hl << 2) + msiz);
  261                 if (m == NULL)
  262                         return;
  263                 ip = mtod(m, struct ip *);
  264                 mip = mtod(m, struct mobip_h *);
  265         }
  266 
  267         mip->mi.ip_dst.s_addr = mip->mh.odst;
  268         mip->mi.ip_p = (ntohs(mip->mh.proto) >> 8);
  269 
  270         if (gre_in_cksum((u_int16_t *)&mip->mh, msiz) != 0) {
  271                 m_freem(m);
  272                 return;
  273         }
  274 
  275         bcopy((caddr_t)(ip) + (ip->ip_hl << 2) + msiz, (caddr_t)(ip) +
  276             (ip->ip_hl << 2), m->m_len - msiz - (ip->ip_hl << 2));
  277         m->m_len -= msiz;
  278         m->m_pkthdr.len -= msiz;
  279 
  280         /*
  281          * On FreeBSD, rip_input() supplies us with ip->ip_len
  282          * already converted into host byteorder and also decreases
  283          * it by the lengh of IP header, however, ip_input() expects
  284          * that this field is in the original format (network byteorder
  285          * and full size of IP packet), so that adjust accordingly.
  286          */
  287         ip->ip_len = htons(ip->ip_len + sizeof(struct ip) - msiz);
  288 
  289         ip->ip_sum = 0;
  290         ip->ip_sum = in_cksum(m, (ip->ip_hl << 2));
  291 
  292         if (bpf_peers_present(GRE2IFP(sc)->if_bpf)) {
  293                 u_int32_t af = AF_INET;
  294                 bpf_mtap2(GRE2IFP(sc)->if_bpf, &af, sizeof(af), m);
  295         }
  296 
  297         if ((GRE2IFP(sc)->if_flags & IFF_MONITOR) != 0) {
  298                 m_freem(m);
  299                 return;
  300         }
  301 
  302         m->m_pkthdr.rcvif = GRE2IFP(sc);
  303 
  304         netisr_queue(NETISR_IP, m);
  305 }
  306 
  307 /*
  308  * Find the gre interface associated with our src/dst/proto set.
  309  *
  310  * XXXRW: Need some sort of drain/refcount mechanism so that the softc
  311  * reference remains valid after it's returned from gre_lookup().  Right
  312  * now, I'm thinking it should be reference-counted with a gre_dropref()
  313  * when the caller is done with the softc.  This is complicated by how
  314  * to handle destroying the gre softc; probably using a gre_drain() in
  315  * in_gre.c during destroy.
  316  */
  317 static struct gre_softc *
  318 gre_lookup(struct mbuf *m, u_int8_t proto)
  319 {
  320         struct ip *ip = mtod(m, struct ip *);
  321         struct gre_softc *sc;
  322 
  323         mtx_lock(&gre_mtx);
  324         for (sc = LIST_FIRST(&gre_softc_list); sc != NULL;
  325              sc = LIST_NEXT(sc, sc_list)) {
  326                 if ((sc->g_dst.s_addr == ip->ip_src.s_addr) &&
  327                     (sc->g_src.s_addr == ip->ip_dst.s_addr) &&
  328                     (sc->g_proto == proto) &&
  329                     ((GRE2IFP(sc)->if_flags & IFF_UP) != 0)) {
  330                         mtx_unlock(&gre_mtx);
  331                         return (sc);
  332                 }
  333         }
  334         mtx_unlock(&gre_mtx);
  335 
  336         return (NULL);
  337 }

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