if_loop.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1993
    3  *      The Regents of the University of California.  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  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)if_loop.c   8.2 (Berkeley) 1/9/95
   30  * $FreeBSD: releng/7.4/sys/net/if_loop.c 178884 2008-05-09 20:39:48Z rwatson $
   31  */
   32 
   33 /*
   34  * Loopback interface driver for protocol testing and timing.
   35  */
   36 
   37 #include "opt_atalk.h"
   38 #include "opt_inet.h"
   39 #include "opt_inet6.h"
   40 #include "opt_ipx.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/kernel.h>
   45 #include <sys/malloc.h>
   46 #include <sys/mbuf.h>
   47 #include <sys/module.h>
   48 #include <machine/bus.h>
   49 #include <sys/rman.h>
   50 #include <sys/socket.h>
   51 #include <sys/sockio.h>
   52 #include <sys/sysctl.h>
   53 
   54 #include <net/if.h>
   55 #include <net/if_clone.h>
   56 #include <net/if_types.h>
   57 #include <net/netisr.h>
   58 #include <net/route.h>
   59 #include <net/bpf.h>
   60 #include <net/bpfdesc.h>
   61 
   62 #ifdef  INET
   63 #include <netinet/in.h>
   64 #include <netinet/in_var.h>
   65 #endif
   66 
   67 #ifdef IPX
   68 #include <netipx/ipx.h>
   69 #include <netipx/ipx_if.h>
   70 #endif
   71 
   72 #ifdef INET6
   73 #ifndef INET
   74 #include <netinet/in.h>
   75 #endif
   76 #include <netinet6/in6_var.h>
   77 #include <netinet/ip6.h>
   78 #endif
   79 
   80 #ifdef NETATALK
   81 #include <netatalk/at.h>
   82 #include <netatalk/at_var.h>
   83 #endif
   84 
   85 #ifdef TINY_LOMTU
   86 #define LOMTU   (1024+512)
   87 #elif defined(LARGE_LOMTU)
   88 #define LOMTU   131072
   89 #else
   90 #define LOMTU   16384
   91 #endif
   92 
   93 #define LONAME  "lo"
   94 
   95 struct lo_softc {
   96         struct  ifnet *sc_ifp;
   97         LIST_ENTRY(lo_softc) sc_next;
   98 };
   99 
  100 int             loioctl(struct ifnet *, u_long, caddr_t);
  101 static void     lortrequest(int, struct rtentry *, struct rt_addrinfo *);
  102 int             looutput(struct ifnet *ifp, struct mbuf *m,
  103                     struct sockaddr *dst, struct rtentry *rt);
  104 static int      lo_clone_create(struct if_clone *, int, caddr_t);
  105 static void     lo_clone_destroy(struct ifnet *);
  106 
  107 struct ifnet *loif = NULL;                      /* Used externally */
  108 
  109 static MALLOC_DEFINE(M_LO, LONAME, "Loopback Interface");
  110 
  111 static struct mtx lo_mtx;
  112 static LIST_HEAD(lo_list, lo_softc) lo_list;
  113 
  114 IFC_SIMPLE_DECLARE(lo, 1);
  115 
  116 static void
  117 lo_clone_destroy(struct ifnet *ifp)
  118 {
  119         struct lo_softc *sc;
  120         
  121         sc = ifp->if_softc;
  122 
  123         /* XXX: destroying lo0 will lead to panics. */
  124         KASSERT(loif != ifp, ("%s: destroying lo0", __func__));
  125 
  126         mtx_lock(&lo_mtx);
  127         LIST_REMOVE(sc, sc_next);
  128         mtx_unlock(&lo_mtx);
  129         bpfdetach(ifp);
  130         if_detach(ifp);
  131         if_free(ifp);
  132         free(sc, M_LO);
  133 }
  134 
  135 static int
  136 lo_clone_create(struct if_clone *ifc, int unit, caddr_t params)
  137 {
  138         struct ifnet *ifp;
  139         struct lo_softc *sc;
  140 
  141         MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
  142         ifp = sc->sc_ifp = if_alloc(IFT_LOOP);
  143         if (ifp == NULL) {
  144                 free(sc, M_LO);
  145                 return (ENOSPC);
  146         }
  147 
  148         if_initname(ifp, ifc->ifc_name, unit);
  149         ifp->if_mtu = LOMTU;
  150         ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  151         ifp->if_ioctl = loioctl;
  152         ifp->if_output = looutput;
  153         ifp->if_snd.ifq_maxlen = ifqmaxlen;
  154         ifp->if_softc = sc;
  155         if_attach(ifp);
  156         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  157         mtx_lock(&lo_mtx);
  158         LIST_INSERT_HEAD(&lo_list, sc, sc_next);
  159         mtx_unlock(&lo_mtx);
  160         if (loif == NULL)
  161                 loif = ifp;
  162 
  163         return (0);
  164 }
  165 
  166 static int
  167 loop_modevent(module_t mod, int type, void *data)
  168 {
  169         switch (type) {
  170         case MOD_LOAD:
  171                 mtx_init(&lo_mtx, "lo_mtx", NULL, MTX_DEF);
  172                 LIST_INIT(&lo_list);
  173                 if_clone_attach(&lo_cloner);
  174                 break;
  175 
  176         case MOD_UNLOAD:
  177                 printf("loop module unload - not possible for this module type\n");
  178                 return (EINVAL);
  179 
  180         default:
  181                 return (EOPNOTSUPP);
  182         }
  183         return (0);
  184 }
  185 
  186 static moduledata_t loop_mod = {
  187         "loop",
  188         loop_modevent,
  189         0
  190 };
  191 
  192 DECLARE_MODULE(loop, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  193 
  194 int
  195 looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
  196     struct rtentry *rt)
  197 {
  198         u_int32_t af;
  199 
  200         M_ASSERTPKTHDR(m); /* check if we have the packet header */
  201 
  202         if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  203                 m_freem(m);
  204                 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  205                         rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  206         }
  207 
  208         ifp->if_opackets++;
  209         ifp->if_obytes += m->m_pkthdr.len;
  210 
  211         /* BPF writes need to be handled specially. */
  212         if (dst->sa_family == AF_UNSPEC) {
  213                 bcopy(dst->sa_data, &af, sizeof(af));
  214                 dst->sa_family = af;
  215         }
  216 
  217 #if 1   /* XXX */
  218         switch (dst->sa_family) {
  219         case AF_INET:
  220         case AF_INET6:
  221         case AF_IPX:
  222         case AF_APPLETALK:
  223                 break;
  224         default:
  225                 printf("looutput: af=%d unexpected\n", dst->sa_family);
  226                 m_freem(m);
  227                 return (EAFNOSUPPORT);
  228         }
  229 #endif
  230         return (if_simloop(ifp, m, dst->sa_family, 0));
  231 }
  232 
  233 /*
  234  * if_simloop()
  235  *
  236  * This function is to support software emulation of hardware loopback,
  237  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
  238  * hear their own broadcasts, we create a copy of the packet that we
  239  * would normally receive via a hardware loopback.
  240  *
  241  * This function expects the packet to include the media header of length hlen.
  242  */
  243 int
  244 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
  245 {
  246         int isr;
  247 
  248         M_ASSERTPKTHDR(m);
  249         m_tag_delete_nonpersistent(m);
  250         m->m_pkthdr.rcvif = ifp;
  251 
  252         /*
  253          * Let BPF see incoming packet in the following manner:
  254          *  - Emulated packet loopback for a simplex interface
  255          *    (net/if_ethersubr.c)
  256          *      -> passes it to ifp's BPF
  257          *  - IPv4/v6 multicast packet loopback (netinet(6)/ip(6)_output.c)
  258          *      -> not passes it to any BPF
  259          *  - Normal packet loopback from myself to myself (net/if_loop.c)
  260          *      -> passes to lo0's BPF (even in case of IPv6, where ifp!=lo0)
  261          */
  262         if (hlen > 0) {
  263                 if (bpf_peers_present(ifp->if_bpf)) {
  264                         bpf_mtap(ifp->if_bpf, m);
  265                 }
  266         } else {
  267                 if (bpf_peers_present(loif->if_bpf)) {
  268                         if ((m->m_flags & M_MCAST) == 0 || loif == ifp) {
  269                                 /* XXX beware sizeof(af) != 4 */
  270                                 u_int32_t af1 = af;     
  271 
  272                                 /*
  273                                  * We need to prepend the address family.
  274                                  */
  275                                 bpf_mtap2(loif->if_bpf, &af1, sizeof(af1), m);
  276                         }
  277                 }
  278         }
  279 
  280         /* Strip away media header */
  281         if (hlen > 0) {
  282                 m_adj(m, hlen);
  283 #ifndef __NO_STRICT_ALIGNMENT
  284                 /*
  285                  * Some archs do not like unaligned data, so
  286                  * we move data down in the first mbuf.
  287                  */
  288                 if (mtod(m, vm_offset_t) & 3) {
  289                         KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  290                         bcopy(m->m_data,
  291                             (char *)(mtod(m, vm_offset_t)
  292                                 - (mtod(m, vm_offset_t) & 3)),
  293                             m->m_len);
  294                         m->m_data -= (mtod(m,vm_offset_t) & 3);
  295                 }
  296 #endif
  297         }
  298 
  299         /* Deliver to upper layer protocol */
  300         switch (af) {
  301 #ifdef INET
  302         case AF_INET:
  303                 isr = NETISR_IP;
  304                 break;
  305 #endif
  306 #ifdef INET6
  307         case AF_INET6:
  308                 m->m_flags |= M_LOOP;
  309                 isr = NETISR_IPV6;
  310                 break;
  311 #endif
  312 #ifdef IPX
  313         case AF_IPX:
  314                 isr = NETISR_IPX;
  315                 break;
  316 #endif
  317 #ifdef NETATALK
  318         case AF_APPLETALK:
  319                 isr = NETISR_ATALK2;
  320                 break;
  321 #endif
  322         default:
  323                 printf("if_simloop: can't handle af=%d\n", af);
  324                 m_freem(m);
  325                 return (EAFNOSUPPORT);
  326         }
  327         ifp->if_ipackets++;
  328         ifp->if_ibytes += m->m_pkthdr.len;
  329         netisr_queue(isr, m);   /* mbuf is free'd on failure. */
  330         return (0);
  331 }
  332 
  333 /* ARGSUSED */
  334 static void
  335 lortrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
  336 {
  337 
  338         RT_LOCK_ASSERT(rt);
  339         rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  340 }
  341 
  342 /*
  343  * Process an ioctl request.
  344  */
  345 /* ARGSUSED */
  346 int
  347 loioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
  348 {
  349         struct ifaddr *ifa;
  350         struct ifreq *ifr = (struct ifreq *)data;
  351         int error = 0;
  352 
  353         switch (cmd) {
  354         case SIOCSIFADDR:
  355                 ifp->if_flags |= IFF_UP;
  356                 ifp->if_drv_flags |= IFF_DRV_RUNNING;
  357                 ifa = (struct ifaddr *)data;
  358                 ifa->ifa_rtrequest = lortrequest;
  359                 /*
  360                  * Everything else is done at a higher level.
  361                  */
  362                 break;
  363 
  364         case SIOCADDMULTI:
  365         case SIOCDELMULTI:
  366                 if (ifr == 0) {
  367                         error = EAFNOSUPPORT;           /* XXX */
  368                         break;
  369                 }
  370                 switch (ifr->ifr_addr.sa_family) {
  371 
  372 #ifdef INET
  373                 case AF_INET:
  374                         break;
  375 #endif
  376 #ifdef INET6
  377                 case AF_INET6:
  378                         break;
  379 #endif
  380 
  381                 default:
  382                         error = EAFNOSUPPORT;
  383                         break;
  384                 }
  385                 break;
  386 
  387         case SIOCSIFMTU:
  388                 ifp->if_mtu = ifr->ifr_mtu;
  389                 break;
  390 
  391         case SIOCSIFFLAGS:
  392                 break;
  393 
  394         default:
  395                 error = EINVAL;
  396         }
  397         return (error);
  398 }
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FreeBSD/Linux Kernel Cross Reference sys/net/if_loop.c

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sys/net/if_loop.c
