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  * 3. All advertising materials mentioning features or use of this software
   21  *    must display the following acknowledgement:
   22  *        This product includes software developed by the NetBSD
   23  *        Foundation, Inc. and its contributors.
   24  * 4. Neither the name of The NetBSD Foundation nor the names of its
   25  *    contributors may be used to endorse or promote products derived
   26  *    from this software without specific prior written permission.
   27  *
   28  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   29  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   30  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   31  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   32  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   33  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   34  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   35  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   36  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   37  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   38  * POSSIBILITY OF SUCH DAMAGE.
   39  */
   40 
   41 /*
   42  * deencapsulate tunneled packets and send them on
   43  * output half is in net/if_gre.[ch]
   44  * This currently handles IPPROTO_GRE, IPPROTO_MOBILE
   45  */
   46 
   47 #include <sys/cdefs.h>
   48 __FBSDID("$FreeBSD: releng/8.1/sys/netinet/ip_gre.c 199583 2009-11-20 15:27:52Z jhb $");
   49 
   50 #include "opt_inet.h"
   51 #include "opt_atalk.h"
   52 #include "opt_inet6.h"
   53 
   54 #include <sys/param.h>
   55 #include <sys/systm.h>
   56 #include <sys/mbuf.h>
   57 #include <sys/socket.h>
   58 #include <sys/socketvar.h>
   59 #include <sys/protosw.h>
   60 #include <sys/errno.h>
   61 #include <sys/time.h>
   62 #include <sys/kernel.h>
   63 #include <sys/syslog.h>
   64 #include <net/bpf.h>
   65 #include <net/ethernet.h>
   66 #include <net/if.h>
   67 #include <net/netisr.h>
   68 #include <net/route.h>
   69 #include <net/raw_cb.h>
   70 
   71 #ifdef INET
   72 #include <netinet/in.h>
   73 #include <netinet/in_var.h>
   74 #include <netinet/in_systm.h>
   75 #include <netinet/ip.h>
   76 #include <netinet/ip_var.h>
   77 #include <netinet/ip_gre.h>
   78 #include <machine/in_cksum.h>
   79 #else
   80 #error ip_gre input without IP?
   81 #endif
   82 
   83 #ifdef NETATALK
   84 #include <netatalk/at.h>
   85 #include <netatalk/at_var.h>
   86 #include <netatalk/at_extern.h>
   87 #endif
   88 
   89 /* Needs IP headers. */
   90 #include <net/if_gre.h>
   91 
   92 #include <machine/stdarg.h>
   93 
   94 #if 1
   95 void gre_inet_ntoa(struct in_addr in);  /* XXX */
   96 #endif
   97 
   98 static struct gre_softc *gre_lookup(struct mbuf *, u_int8_t);
   99 
  100 static struct mbuf *gre_input2(struct mbuf *, int, u_char);
  101 
  102 /*
  103  * De-encapsulate a packet and feed it back through ip input (this
  104  * routine is called whenever IP gets a packet with proto type
  105  * IPPROTO_GRE and a local destination address).
  106  * This really is simple
  107  */
  108 void
  109 gre_input(struct mbuf *m, int off)
  110 {
  111         int proto;
  112 
  113         proto = (mtod(m, struct ip *))->ip_p;
  114 
  115         m = gre_input2(m, off, proto);
  116 
  117         /*
  118          * If no matching tunnel that is up is found. We inject
  119          * the mbuf to raw ip socket to see if anyone picks it up.
  120          */
  121         if (m != NULL)
  122                 rip_input(m, off);
  123 }
  124 
  125 /*
  126  * Decapsulate. Does the real work and is called from gre_input()
  127  * (above). Returns an mbuf back if packet is not yet processed,
  128  * and NULL if it needs no further processing. proto is the protocol
  129  * number of the "calling" foo_input() routine.
  130  */
  131 static struct mbuf *
  132 gre_input2(struct mbuf *m ,int hlen, u_char proto)
  133 {
  134         struct greip *gip;
  135         int isr;
  136         struct gre_softc *sc;
  137         u_int16_t flags;
  138         u_int32_t af;
  139 
  140         if ((sc = gre_lookup(m, proto)) == NULL) {
  141                 /* No matching tunnel or tunnel is down. */
  142                 return (m);
  143         }
  144 
  145         if (m->m_len < sizeof(*gip)) {
  146                 m = m_pullup(m, sizeof(*gip));
  147                 if (m == NULL)
  148                         return (NULL);
  149         }
  150         gip = mtod(m, struct greip *);
  151 
  152         GRE2IFP(sc)->if_ipackets++;
  153         GRE2IFP(sc)->if_ibytes += m->m_pkthdr.len;
  154 
  155         switch (proto) {
  156         case IPPROTO_GRE:
  157                 hlen += sizeof(struct gre_h);
  158 
  159                 /* process GRE flags as packet can be of variable len */
  160                 flags = ntohs(gip->gi_flags);
  161 
  162                 /* Checksum & Offset are present */
  163                 if ((flags & GRE_CP) | (flags & GRE_RP))
  164                         hlen += 4;
  165                 /* We don't support routing fields (variable length) */
  166                 if (flags & GRE_RP)
  167                         return (m);
  168                 if (flags & GRE_KP)
  169                         hlen += 4;
  170                 if (flags & GRE_SP)
  171                         hlen += 4;
  172 
  173                 switch (ntohs(gip->gi_ptype)) { /* ethertypes */
  174                 case WCCP_PROTOCOL_TYPE:
  175                         if (sc->wccp_ver == WCCP_V2)
  176                                 hlen += 4;
  177                         /* FALLTHROUGH */
  178                 case ETHERTYPE_IP:      /* shouldn't need a schednetisr(), */
  179                         isr = NETISR_IP;/* as we are in ip_input */
  180                         af = AF_INET;
  181                         break;
  182 #ifdef INET6
  183                 case ETHERTYPE_IPV6:
  184                         isr = NETISR_IPV6;
  185                         af = AF_INET6;
  186                         break;
  187 #endif
  188 #ifdef NETATALK
  189                 case ETHERTYPE_ATALK:
  190                         isr = NETISR_ATALK1;
  191                         af = AF_APPLETALK;
  192                         break;
  193 #endif
  194                 default:
  195                         /* Others not yet supported. */
  196                         return (m);
  197                 }
  198                 break;
  199         default:
  200                 /* Others not yet supported. */
  201                 return (m);
  202         }
  203 
  204         if (hlen > m->m_pkthdr.len) {
  205                 m_freem(m);
  206                 return (NULL);
  207         }
  208         /* Unlike NetBSD, in FreeBSD m_adj() adjusts m->m_pkthdr.len as well */
  209         m_adj(m, hlen);
  210 
  211         if (bpf_peers_present(GRE2IFP(sc)->if_bpf)) {
  212                 bpf_mtap2(GRE2IFP(sc)->if_bpf, &af, sizeof(af), m);
  213         }
  214 
  215         m->m_pkthdr.rcvif = GRE2IFP(sc);
  216 
  217         netisr_queue(isr, m);
  218 
  219         /* Packet is done, no further processing needed. */
  220         return (NULL);
  221 }
  222 
  223 /*
  224  * input routine for IPPRPOTO_MOBILE
  225  * This is a little bit diffrent from the other modes, as the
  226  * encapsulating header was not prepended, but instead inserted
  227  * between IP header and payload
  228  */
  229 
  230 void
  231 gre_mobile_input(struct mbuf *m, int hlen)
  232 {
  233         struct ip *ip;
  234         struct mobip_h *mip;
  235         struct gre_softc *sc;
  236         int msiz;
  237 
  238         if ((sc = gre_lookup(m, IPPROTO_MOBILE)) == NULL) {
  239                 /* No matching tunnel or tunnel is down. */
  240                 m_freem(m);
  241                 return;
  242         }
  243 
  244         if (m->m_len < sizeof(*mip)) {
  245                 m = m_pullup(m, sizeof(*mip));
  246                 if (m == NULL)
  247                         return;
  248         }
  249         ip = mtod(m, struct ip *);
  250         mip = mtod(m, struct mobip_h *);
  251 
  252         GRE2IFP(sc)->if_ipackets++;
  253         GRE2IFP(sc)->if_ibytes += m->m_pkthdr.len;
  254 
  255         if (ntohs(mip->mh.proto) & MOB_H_SBIT) {
  256                 msiz = MOB_H_SIZ_L;
  257                 mip->mi.ip_src.s_addr = mip->mh.osrc;
  258         } else
  259                 msiz = MOB_H_SIZ_S;
  260 
  261         if (m->m_len < (ip->ip_hl << 2) + msiz) {
  262                 m = m_pullup(m, (ip->ip_hl << 2) + msiz);
  263                 if (m == NULL)
  264                         return;
  265                 ip = mtod(m, struct ip *);
  266                 mip = mtod(m, struct mobip_h *);
  267         }
  268 
  269         mip->mi.ip_dst.s_addr = mip->mh.odst;
  270         mip->mi.ip_p = (ntohs(mip->mh.proto) >> 8);
  271 
  272         if (gre_in_cksum((u_int16_t *)&mip->mh, msiz) != 0) {
  273                 m_freem(m);
  274                 return;
  275         }
  276 
  277         bcopy((caddr_t)(ip) + (ip->ip_hl << 2) + msiz, (caddr_t)(ip) +
  278             (ip->ip_hl << 2), m->m_len - msiz - (ip->ip_hl << 2));
  279         m->m_len -= msiz;
  280         m->m_pkthdr.len -= msiz;
  281 
  282         /*
  283          * On FreeBSD, rip_input() supplies us with ip->ip_len
  284          * already converted into host byteorder and also decreases
  285          * it by the lengh of IP header, however, ip_input() expects
  286          * that this field is in the original format (network byteorder
  287          * and full size of IP packet), so that adjust accordingly.
  288          */
  289         ip->ip_len = htons(ip->ip_len + sizeof(struct ip) - msiz);
  290 
  291         ip->ip_sum = 0;
  292         ip->ip_sum = in_cksum(m, (ip->ip_hl << 2));
  293 
  294         if (bpf_peers_present(GRE2IFP(sc)->if_bpf)) {
  295                 u_int32_t af = AF_INET;
  296                 bpf_mtap2(GRE2IFP(sc)->if_bpf, &af, sizeof(af), m);
  297         }
  298 
  299         m->m_pkthdr.rcvif = GRE2IFP(sc);
  300 
  301         netisr_queue(NETISR_IP, m);
  302 }
  303 
  304 /*
  305  * Find the gre interface associated with our src/dst/proto set.
  306  *
  307  * XXXRW: Need some sort of drain/refcount mechanism so that the softc
  308  * reference remains valid after it's returned from gre_lookup().  Right
  309  * now, I'm thinking it should be reference-counted with a gre_dropref()
  310  * when the caller is done with the softc.  This is complicated by how
  311  * to handle destroying the gre softc; probably using a gre_drain() in
  312  * in_gre.c during destroy.
  313  */
  314 static struct gre_softc *
  315 gre_lookup(struct mbuf *m, u_int8_t proto)
  316 {
  317         struct ip *ip = mtod(m, struct ip *);
  318         struct gre_softc *sc;
  319 
  320         mtx_lock(&gre_mtx);
  321         for (sc = LIST_FIRST(&gre_softc_list); sc != NULL;
  322              sc = LIST_NEXT(sc, sc_list)) {
  323                 if ((sc->g_dst.s_addr == ip->ip_src.s_addr) &&
  324                     (sc->g_src.s_addr == ip->ip_dst.s_addr) &&
  325                     (sc->g_proto == proto) &&
  326                     ((GRE2IFP(sc)->if_flags & IFF_UP) != 0)) {
  327                         mtx_unlock(&gre_mtx);
  328                         return (sc);
  329                 }
  330         }
  331         mtx_unlock(&gre_mtx);
  332 
  333         return (NULL);
  334 }

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