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/net/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/10.1/sys/net/if_loop.c 263478 2014-03-21 15:15:30Z glebius $
   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/mbuf.h>
   46 #include <sys/module.h>
   47 #include <machine/bus.h>
   48 #include <sys/rman.h>
   49 #include <sys/socket.h>
   50 #include <sys/sockio.h>
   51 #include <sys/sysctl.h>
   52 
   53 #include <net/if.h>
   54 #include <net/if_clone.h>
   55 #include <net/if_types.h>
   56 #include <net/netisr.h>
   57 #include <net/route.h>
   58 #include <net/bpf.h>
   59 #include <net/vnet.h>
   60 
   61 #ifdef  INET
   62 #include <netinet/in.h>
   63 #include <netinet/in_var.h>
   64 #endif
   65 
   66 #ifdef IPX
   67 #include <netipx/ipx.h>
   68 #include <netipx/ipx_if.h>
   69 #endif
   70 
   71 #ifdef INET6
   72 #ifndef INET
   73 #include <netinet/in.h>
   74 #endif
   75 #include <netinet6/in6_var.h>
   76 #include <netinet/ip6.h>
   77 #endif
   78 
   79 #ifdef NETATALK
   80 #include <netatalk/at.h>
   81 #include <netatalk/at_var.h>
   82 #endif
   83 
   84 #include <security/mac/mac_framework.h>
   85 
   86 #ifdef TINY_LOMTU
   87 #define LOMTU   (1024+512)
   88 #elif defined(LARGE_LOMTU)
   89 #define LOMTU   131072
   90 #else
   91 #define LOMTU   16384
   92 #endif
   93 
   94 #define LO_CSUM_FEATURES        (CSUM_IP | CSUM_TCP | CSUM_UDP | CSUM_SCTP)
   95 #define LO_CSUM_FEATURES6       (CSUM_TCP_IPV6 | CSUM_UDP_IPV6 | CSUM_SCTP_IPV6)
   96 #define LO_CSUM_SET             (CSUM_DATA_VALID | CSUM_DATA_VALID_IPV6 | \
   97                                     CSUM_PSEUDO_HDR | \
   98                                     CSUM_IP_CHECKED | CSUM_IP_VALID | \
   99                                     CSUM_SCTP_VALID)
  100 
  101 int             loioctl(struct ifnet *, u_long, caddr_t);
  102 static void     lortrequest(int, struct rtentry *, struct rt_addrinfo *);
  103 int             looutput(struct ifnet *ifp, struct mbuf *m,
  104                     const struct sockaddr *dst, struct route *ro);
  105 static int      lo_clone_create(struct if_clone *, int, caddr_t);
  106 static void     lo_clone_destroy(struct ifnet *);
  107 
  108 VNET_DEFINE(struct ifnet *, loif);      /* Used externally */
  109 
  110 #ifdef VIMAGE
  111 static VNET_DEFINE(struct if_clone *, lo_cloner);
  112 #define V_lo_cloner             VNET(lo_cloner)
  113 #endif
  114 
  115 static struct if_clone *lo_cloner;
  116 static const char loname[] = "lo";
  117 
  118 static void
  119 lo_clone_destroy(struct ifnet *ifp)
  120 {
  121 
  122 #ifndef VIMAGE
  123         /* XXX: destroying lo0 will lead to panics. */
  124         KASSERT(V_loif != ifp, ("%s: destroying lo0", __func__));
  125 #endif
  126 
  127         bpfdetach(ifp);
  128         if_detach(ifp);
  129         if_free(ifp);
  130 }
  131 
  132 static int
  133 lo_clone_create(struct if_clone *ifc, int unit, caddr_t params)
  134 {
  135         struct ifnet *ifp;
  136 
  137         ifp = if_alloc(IFT_LOOP);
  138         if (ifp == NULL)
  139                 return (ENOSPC);
  140 
  141         if_initname(ifp, loname, unit);
  142         ifp->if_mtu = LOMTU;
  143         ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  144         ifp->if_ioctl = loioctl;
  145         ifp->if_output = looutput;
  146         ifp->if_snd.ifq_maxlen = ifqmaxlen;
  147         ifp->if_capabilities = ifp->if_capenable =
  148             IFCAP_HWCSUM | IFCAP_HWCSUM_IPV6;
  149         ifp->if_hwassist = LO_CSUM_FEATURES | LO_CSUM_FEATURES6;
  150         if_attach(ifp);
  151         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  152         if (V_loif == NULL)
  153                 V_loif = ifp;
  154 
  155         return (0);
  156 }
  157 
  158 static void
  159 vnet_loif_init(const void *unused __unused)
  160 {
  161 
  162 #ifdef VIMAGE
  163         lo_cloner = if_clone_simple(loname, lo_clone_create, lo_clone_destroy,
  164             1);
  165         V_lo_cloner = lo_cloner;
  166 #else
  167         lo_cloner = if_clone_simple(loname, lo_clone_create, lo_clone_destroy,
  168             1);
  169 #endif
  170 }
  171 VNET_SYSINIT(vnet_loif_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
  172     vnet_loif_init, NULL);
  173 
  174 #ifdef VIMAGE
  175 static void
  176 vnet_loif_uninit(const void *unused __unused)
  177 {
  178 
  179         if_clone_detach(V_lo_cloner);
  180         V_loif = NULL;
  181 }
  182 VNET_SYSUNINIT(vnet_loif_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
  183     vnet_loif_uninit, NULL);
  184 #endif
  185 
  186 static int
  187 loop_modevent(module_t mod, int type, void *data)
  188 {
  189 
  190         switch (type) {
  191         case MOD_LOAD:
  192                 break;
  193 
  194         case MOD_UNLOAD:
  195                 printf("loop module unload - not possible for this module type\n");
  196                 return (EINVAL);
  197 
  198         default:
  199                 return (EOPNOTSUPP);
  200         }
  201         return (0);
  202 }
  203 
  204 static moduledata_t loop_mod = {
  205         "if_lo",
  206         loop_modevent,
  207         0
  208 };
  209 
  210 DECLARE_MODULE(if_lo, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  211 
  212 int
  213 looutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
  214     struct route *ro)
  215 {
  216         u_int32_t af;
  217         struct rtentry *rt = NULL;
  218 #ifdef MAC
  219         int error;
  220 #endif
  221 
  222         M_ASSERTPKTHDR(m); /* check if we have the packet header */
  223 
  224         if (ro != NULL)
  225                 rt = ro->ro_rt;
  226 #ifdef MAC
  227         error = mac_ifnet_check_transmit(ifp, m);
  228         if (error) {
  229                 m_freem(m);
  230                 return (error);
  231         }
  232 #endif
  233 
  234         if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  235                 m_freem(m);
  236                 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  237                         rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  238         }
  239 
  240         ifp->if_opackets++;
  241         ifp->if_obytes += m->m_pkthdr.len;
  242 
  243         /* BPF writes need to be handled specially. */
  244         if (dst->sa_family == AF_UNSPEC)
  245                 bcopy(dst->sa_data, &af, sizeof(af));
  246         else
  247                 af = dst->sa_family;
  248 
  249 #if 1   /* XXX */
  250         switch (af) {
  251         case AF_INET:
  252                 if (ifp->if_capenable & IFCAP_RXCSUM) {
  253                         m->m_pkthdr.csum_data = 0xffff;
  254                         m->m_pkthdr.csum_flags = LO_CSUM_SET;
  255                 }
  256                 m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES;
  257                 break;
  258         case AF_INET6:
  259 #if 0
  260                 /*
  261                  * XXX-BZ for now always claim the checksum is good despite
  262                  * any interface flags.   This is a workaround for 9.1-R and
  263                  * a proper solution ought to be sought later.
  264                  */
  265                 if (ifp->if_capenable & IFCAP_RXCSUM_IPV6) {
  266                         m->m_pkthdr.csum_data = 0xffff;
  267                         m->m_pkthdr.csum_flags = LO_CSUM_SET;
  268                 }
  269 #else
  270                 m->m_pkthdr.csum_data = 0xffff;
  271                 m->m_pkthdr.csum_flags = LO_CSUM_SET;
  272 #endif
  273                 m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES6;
  274                 break;
  275         case AF_IPX:
  276         case AF_APPLETALK:
  277                 break;
  278         default:
  279                 printf("looutput: af=%d unexpected\n", af);
  280                 m_freem(m);
  281                 return (EAFNOSUPPORT);
  282         }
  283 #endif
  284         return (if_simloop(ifp, m, af, 0));
  285 }
  286 
  287 /*
  288  * if_simloop()
  289  *
  290  * This function is to support software emulation of hardware loopback,
  291  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
  292  * hear their own broadcasts, we create a copy of the packet that we
  293  * would normally receive via a hardware loopback.
  294  *
  295  * This function expects the packet to include the media header of length hlen.
  296  */
  297 int
  298 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
  299 {
  300         int isr;
  301 
  302         M_ASSERTPKTHDR(m);
  303         m_tag_delete_nonpersistent(m);
  304         m->m_pkthdr.rcvif = ifp;
  305 
  306 #ifdef MAC
  307         mac_ifnet_create_mbuf(ifp, m);
  308 #endif
  309 
  310         /*
  311          * Let BPF see incoming packet in the following manner:
  312          *  - Emulated packet loopback for a simplex interface
  313          *    (net/if_ethersubr.c)
  314          *      -> passes it to ifp's BPF
  315          *  - IPv4/v6 multicast packet loopback (netinet(6)/ip(6)_output.c)
  316          *      -> not passes it to any BPF
  317          *  - Normal packet loopback from myself to myself (net/if_loop.c)
  318          *      -> passes to lo0's BPF (even in case of IPv6, where ifp!=lo0)
  319          */
  320         if (hlen > 0) {
  321                 if (bpf_peers_present(ifp->if_bpf)) {
  322                         bpf_mtap(ifp->if_bpf, m);
  323                 }
  324         } else {
  325                 if (bpf_peers_present(V_loif->if_bpf)) {
  326                         if ((m->m_flags & M_MCAST) == 0 || V_loif == ifp) {
  327                                 /* XXX beware sizeof(af) != 4 */
  328                                 u_int32_t af1 = af;
  329 
  330                                 /*
  331                                  * We need to prepend the address family.
  332                                  */
  333                                 bpf_mtap2(V_loif->if_bpf, &af1, sizeof(af1), m);
  334                         }
  335                 }
  336         }
  337 
  338         /* Strip away media header */
  339         if (hlen > 0) {
  340                 m_adj(m, hlen);
  341 #ifndef __NO_STRICT_ALIGNMENT
  342                 /*
  343                  * Some archs do not like unaligned data, so
  344                  * we move data down in the first mbuf.
  345                  */
  346                 if (mtod(m, vm_offset_t) & 3) {
  347                         KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  348                         bcopy(m->m_data,
  349                             (char *)(mtod(m, vm_offset_t)
  350                                 - (mtod(m, vm_offset_t) & 3)),
  351                             m->m_len);
  352                         m->m_data -= (mtod(m,vm_offset_t) & 3);
  353                 }
  354 #endif
  355         }
  356 
  357         /* Deliver to upper layer protocol */
  358         switch (af) {
  359 #ifdef INET
  360         case AF_INET:
  361                 isr = NETISR_IP;
  362                 break;
  363 #endif
  364 #ifdef INET6
  365         case AF_INET6:
  366                 m->m_flags |= M_LOOP;
  367                 isr = NETISR_IPV6;
  368                 break;
  369 #endif
  370 #ifdef IPX
  371         case AF_IPX:
  372                 isr = NETISR_IPX;
  373                 break;
  374 #endif
  375 #ifdef NETATALK
  376         case AF_APPLETALK:
  377                 isr = NETISR_ATALK2;
  378                 break;
  379 #endif
  380         default:
  381                 printf("if_simloop: can't handle af=%d\n", af);
  382                 m_freem(m);
  383                 return (EAFNOSUPPORT);
  384         }
  385         ifp->if_ipackets++;
  386         ifp->if_ibytes += m->m_pkthdr.len;
  387         netisr_queue(isr, m);   /* mbuf is free'd on failure. */
  388         return (0);
  389 }
  390 
  391 /* ARGSUSED */
  392 static void
  393 lortrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
  394 {
  395 
  396         RT_LOCK_ASSERT(rt);
  397         rt->rt_mtu = rt->rt_ifp->if_mtu;
  398 }
  399 
  400 /*
  401  * Process an ioctl request.
  402  */
  403 /* ARGSUSED */
  404 int
  405 loioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
  406 {
  407         struct ifaddr *ifa;
  408         struct ifreq *ifr = (struct ifreq *)data;
  409         int error = 0, mask;
  410 
  411         switch (cmd) {
  412         case SIOCSIFADDR:
  413                 ifp->if_flags |= IFF_UP;
  414                 ifp->if_drv_flags |= IFF_DRV_RUNNING;
  415                 ifa = (struct ifaddr *)data;
  416                 ifa->ifa_rtrequest = lortrequest;
  417                 /*
  418                  * Everything else is done at a higher level.
  419                  */
  420                 break;
  421 
  422         case SIOCADDMULTI:
  423         case SIOCDELMULTI:
  424                 if (ifr == 0) {
  425                         error = EAFNOSUPPORT;           /* XXX */
  426                         break;
  427                 }
  428                 switch (ifr->ifr_addr.sa_family) {
  429 
  430 #ifdef INET
  431                 case AF_INET:
  432                         break;
  433 #endif
  434 #ifdef INET6
  435                 case AF_INET6:
  436                         break;
  437 #endif
  438 
  439                 default:
  440                         error = EAFNOSUPPORT;
  441                         break;
  442                 }
  443                 break;
  444 
  445         case SIOCSIFMTU:
  446                 ifp->if_mtu = ifr->ifr_mtu;
  447                 break;
  448 
  449         case SIOCSIFFLAGS:
  450                 break;
  451 
  452         case SIOCSIFCAP:
  453                 mask = ifp->if_capenable ^ ifr->ifr_reqcap;
  454                 if ((mask & IFCAP_RXCSUM) != 0)
  455                         ifp->if_capenable ^= IFCAP_RXCSUM;
  456                 if ((mask & IFCAP_TXCSUM) != 0)
  457                         ifp->if_capenable ^= IFCAP_TXCSUM;
  458                 if ((mask & IFCAP_RXCSUM_IPV6) != 0) {
  459 #if 0
  460                         ifp->if_capenable ^= IFCAP_RXCSUM_IPV6;
  461 #else
  462                         error = EOPNOTSUPP;
  463                         break;
  464 #endif
  465                 }
  466                 if ((mask & IFCAP_TXCSUM_IPV6) != 0) {
  467 #if 0
  468                         ifp->if_capenable ^= IFCAP_TXCSUM_IPV6;
  469 #else
  470                         error = EOPNOTSUPP;
  471                         break;
  472 #endif
  473                 }
  474                 ifp->if_hwassist = 0;
  475                 if (ifp->if_capenable & IFCAP_TXCSUM)
  476                         ifp->if_hwassist = LO_CSUM_FEATURES;
  477 #if 0
  478                 if (ifp->if_capenable & IFCAP_TXCSUM_IPV6)
  479                         ifp->if_hwassist |= LO_CSUM_FEATURES6;
  480 #endif
  481                 break;
  482 
  483         default:
  484                 error = EINVAL;
  485         }
  486         return (error);
  487 }

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