The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_options.c

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    1 /*
    2  * Copyright (c) 1982, 1986, 1988, 1993
    3  *      The Regents of the University of California.
    4  * Copyright (c) 2005 Andre Oppermann, Internet Business Solutions AG.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 4. Neither the name of the University nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD$");
   34 
   35 #include "opt_ipstealth.h"
   36 #include "opt_mac.h"
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/mbuf.h>
   41 #include <sys/domain.h>
   42 #include <sys/protosw.h>
   43 #include <sys/socket.h>
   44 #include <sys/time.h>
   45 #include <sys/kernel.h>
   46 #include <sys/syslog.h>
   47 #include <sys/sysctl.h>
   48 
   49 #include <net/if.h>
   50 #include <net/if_types.h>
   51 #include <net/if_var.h>
   52 #include <net/if_dl.h>
   53 #include <net/route.h>
   54 #include <net/netisr.h>
   55 
   56 #include <netinet/in.h>
   57 #include <netinet/in_systm.h>
   58 #include <netinet/in_var.h>
   59 #include <netinet/ip.h>
   60 #include <netinet/in_pcb.h>
   61 #include <netinet/ip_var.h>
   62 #include <netinet/ip_options.h>
   63 #include <netinet/ip_icmp.h>
   64 #include <machine/in_cksum.h>
   65 
   66 #include <sys/socketvar.h>
   67 
   68 #include <security/mac/mac_framework.h>
   69 
   70 static int      ip_dosourceroute = 0;
   71 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
   72     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
   73 
   74 static int      ip_acceptsourceroute = 0;
   75 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, 
   76     CTLFLAG_RW, &ip_acceptsourceroute, 0, 
   77     "Enable accepting source routed IP packets");
   78 
   79 int             ip_doopts = 1;  /* 0 = ignore, 1 = process, 2 = reject */
   80 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
   81     &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
   82 
   83 static void     save_rte(struct mbuf *m, u_char *, struct in_addr);
   84 
   85 /*
   86  * Do option processing on a datagram, possibly discarding it if bad options
   87  * are encountered, or forwarding it if source-routed.
   88  *
   89  * The pass argument is used when operating in the IPSTEALTH mode to tell
   90  * what options to process: [LS]SRR (pass 0) or the others (pass 1).  The
   91  * reason for as many as two passes is that when doing IPSTEALTH, non-routing
   92  * options should be processed only if the packet is for us.
   93  *
   94  * Returns 1 if packet has been forwarded/freed, 0 if the packet should be
   95  * processed further.
   96  */
   97 int
   98 ip_dooptions(struct mbuf *m, int pass)
   99 {
  100         struct ip *ip = mtod(m, struct ip *);
  101         u_char *cp;
  102         struct in_ifaddr *ia;
  103         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
  104         struct in_addr *sin, dst;
  105         uint32_t ntime;
  106         struct  sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
  107 
  108         /* Ignore or reject packets with IP options. */
  109         if (ip_doopts == 0)
  110                 return 0;
  111         else if (ip_doopts == 2) {
  112                 type = ICMP_UNREACH;
  113                 code = ICMP_UNREACH_FILTER_PROHIB;
  114                 goto bad;
  115         }
  116 
  117         dst = ip->ip_dst;
  118         cp = (u_char *)(ip + 1);
  119         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
  120         for (; cnt > 0; cnt -= optlen, cp += optlen) {
  121                 opt = cp[IPOPT_OPTVAL];
  122                 if (opt == IPOPT_EOL)
  123                         break;
  124                 if (opt == IPOPT_NOP)
  125                         optlen = 1;
  126                 else {
  127                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
  128                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
  129                                 goto bad;
  130                         }
  131                         optlen = cp[IPOPT_OLEN];
  132                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
  133                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
  134                                 goto bad;
  135                         }
  136                 }
  137                 switch (opt) {
  138 
  139                 default:
  140                         break;
  141 
  142                 /*
  143                  * Source routing with record.  Find interface with current
  144                  * destination address.  If none on this machine then drop if
  145                  * strictly routed, or do nothing if loosely routed.  Record
  146                  * interface address and bring up next address component.  If
  147                  * strictly routed make sure next address is on directly
  148                  * accessible net.
  149                  */
  150                 case IPOPT_LSRR:
  151                 case IPOPT_SSRR:
  152 #ifdef IPSTEALTH
  153                         if (ipstealth && pass > 0)
  154                                 break;
  155 #endif
  156                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
  157                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
  158                                 goto bad;
  159                         }
  160                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
  161                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  162                                 goto bad;
  163                         }
  164                         ipaddr.sin_addr = ip->ip_dst;
  165                         ia = (struct in_ifaddr *)
  166                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
  167                         if (ia == NULL) {
  168                                 if (opt == IPOPT_SSRR) {
  169                                         type = ICMP_UNREACH;
  170                                         code = ICMP_UNREACH_SRCFAIL;
  171                                         goto bad;
  172                                 }
  173                                 if (!ip_dosourceroute)
  174                                         goto nosourcerouting;
  175                                 /*
  176                                  * Loose routing, and not at next destination
  177                                  * yet; nothing to do except forward.
  178                                  */
  179                                 break;
  180                         }
  181                         off--;                  /* 0 origin */
  182                         if (off > optlen - (int)sizeof(struct in_addr)) {
  183                                 /*
  184                                  * End of source route.  Should be for us.
  185                                  */
  186                                 if (!ip_acceptsourceroute)
  187                                         goto nosourcerouting;
  188                                 save_rte(m, cp, ip->ip_src);
  189                                 break;
  190                         }
  191 #ifdef IPSTEALTH
  192                         if (ipstealth)
  193                                 goto dropit;
  194 #endif
  195                         if (!ip_dosourceroute) {
  196                                 if (ipforwarding) {
  197                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
  198                                         /*
  199                                          * Acting as a router, so generate
  200                                          * ICMP
  201                                          */
  202 nosourcerouting:
  203                                         strcpy(buf, inet_ntoa(ip->ip_dst));
  204                                         log(LOG_WARNING, 
  205                                             "attempted source route from %s to %s\n",
  206                                             inet_ntoa(ip->ip_src), buf);
  207                                         type = ICMP_UNREACH;
  208                                         code = ICMP_UNREACH_SRCFAIL;
  209                                         goto bad;
  210                                 } else {
  211                                         /*
  212                                          * Not acting as a router, so
  213                                          * silently drop.
  214                                          */
  215 #ifdef IPSTEALTH
  216 dropit:
  217 #endif
  218                                         ipstat.ips_cantforward++;
  219                                         m_freem(m);
  220                                         return (1);
  221                                 }
  222                         }
  223 
  224                         /*
  225                          * locate outgoing interface
  226                          */
  227                         (void)memcpy(&ipaddr.sin_addr, cp + off,
  228                             sizeof(ipaddr.sin_addr));
  229 
  230                         if (opt == IPOPT_SSRR) {
  231 #define INA     struct in_ifaddr *
  232 #define SA      struct sockaddr *
  233                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
  234                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
  235                         } else
  236 /* XXX MRT 0 for routing */
  237                                 ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m));
  238                         if (ia == NULL) {
  239                                 type = ICMP_UNREACH;
  240                                 code = ICMP_UNREACH_SRCFAIL;
  241                                 goto bad;
  242                         }
  243                         ip->ip_dst = ipaddr.sin_addr;
  244                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
  245                             sizeof(struct in_addr));
  246                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
  247                         /*
  248                          * Let ip_intr's mcast routing check handle mcast pkts
  249                          */
  250                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
  251                         break;
  252 
  253                 case IPOPT_RR:
  254 #ifdef IPSTEALTH
  255                         if (ipstealth && pass == 0)
  256                                 break;
  257 #endif
  258                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
  259                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  260                                 goto bad;
  261                         }
  262                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
  263                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  264                                 goto bad;
  265                         }
  266                         /*
  267                          * If no space remains, ignore.
  268                          */
  269                         off--;                  /* 0 origin */
  270                         if (off > optlen - (int)sizeof(struct in_addr))
  271                                 break;
  272                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
  273                             sizeof(ipaddr.sin_addr));
  274                         /*
  275                          * Locate outgoing interface; if we're the
  276                          * destination, use the incoming interface (should be
  277                          * same).
  278                          */
  279                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
  280                             (ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m))) == NULL) {
  281                                 type = ICMP_UNREACH;
  282                                 code = ICMP_UNREACH_HOST;
  283                                 goto bad;
  284                         }
  285                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
  286                             sizeof(struct in_addr));
  287                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
  288                         break;
  289 
  290                 case IPOPT_TS:
  291 #ifdef IPSTEALTH
  292                         if (ipstealth && pass == 0)
  293                                 break;
  294 #endif
  295                         code = cp - (u_char *)ip;
  296                         if (optlen < 4 || optlen > 40) {
  297                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
  298                                 goto bad;
  299                         }
  300                         if ((off = cp[IPOPT_OFFSET]) < 5) {
  301                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
  302                                 goto bad;
  303                         }
  304                         if (off > optlen - (int)sizeof(int32_t)) {
  305                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
  306                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
  307                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  308                                         goto bad;
  309                                 }
  310                                 break;
  311                         }
  312                         off--;                          /* 0 origin */
  313                         sin = (struct in_addr *)(cp + off);
  314                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
  315 
  316                         case IPOPT_TS_TSONLY:
  317                                 break;
  318 
  319                         case IPOPT_TS_TSANDADDR:
  320                                 if (off + sizeof(uint32_t) +
  321                                     sizeof(struct in_addr) > optlen) {
  322                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  323                                         goto bad;
  324                                 }
  325                                 ipaddr.sin_addr = dst;
  326                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
  327                                                             m->m_pkthdr.rcvif);
  328                                 if (ia == NULL)
  329                                         continue;
  330                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
  331                                     sizeof(struct in_addr));
  332                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
  333                                 off += sizeof(struct in_addr);
  334                                 break;
  335 
  336                         case IPOPT_TS_PRESPEC:
  337                                 if (off + sizeof(uint32_t) +
  338                                     sizeof(struct in_addr) > optlen) {
  339                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  340                                         goto bad;
  341                                 }
  342                                 (void)memcpy(&ipaddr.sin_addr, sin,
  343                                     sizeof(struct in_addr));
  344                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
  345                                         continue;
  346                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
  347                                 off += sizeof(struct in_addr);
  348                                 break;
  349 
  350                         default:
  351                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
  352                                 goto bad;
  353                         }
  354                         ntime = iptime();
  355                         (void)memcpy(cp + off, &ntime, sizeof(uint32_t));
  356                         cp[IPOPT_OFFSET] += sizeof(uint32_t);
  357                 }
  358         }
  359         if (forward && ipforwarding) {
  360                 ip_forward(m, 1);
  361                 return (1);
  362         }
  363         return (0);
  364 bad:
  365         icmp_error(m, type, code, 0, 0);
  366         ipstat.ips_badoptions++;
  367         return (1);
  368 }
  369 
  370 /*
  371  * Save incoming source route for use in replies, to be picked up later by
  372  * ip_srcroute if the receiver is interested.
  373  */
  374 static void
  375 save_rte(struct mbuf *m, u_char *option, struct in_addr dst)
  376 {
  377         unsigned olen;
  378         struct ipopt_tag *opts;
  379 
  380         opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
  381             sizeof(struct ipopt_tag), M_NOWAIT);
  382         if (opts == NULL)
  383                 return;
  384 
  385         olen = option[IPOPT_OLEN];
  386         if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
  387                 m_tag_free((struct m_tag *)opts);
  388                 return;
  389         }
  390         bcopy(option, opts->ip_srcrt.srcopt, olen);
  391         opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
  392         opts->ip_srcrt.dst = dst;
  393         m_tag_prepend(m, (struct m_tag *)opts);
  394 }
  395 
  396 /*
  397  * Retrieve incoming source route for use in replies, in the same form used
  398  * by setsockopt.  The first hop is placed before the options, will be
  399  * removed later.
  400  */
  401 struct mbuf *
  402 ip_srcroute(struct mbuf *m0)
  403 {
  404         struct in_addr *p, *q;
  405         struct mbuf *m;
  406         struct ipopt_tag *opts;
  407 
  408         opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
  409         if (opts == NULL)
  410                 return (NULL);
  411 
  412         if (opts->ip_nhops == 0)
  413                 return (NULL);
  414         m = m_get(M_DONTWAIT, MT_DATA);
  415         if (m == NULL)
  416                 return (NULL);
  417 
  418 #define OPTSIZ  (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
  419 
  420         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
  421         m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
  422             sizeof(struct in_addr) + OPTSIZ;
  423 
  424         /*
  425          * First, save first hop for return route.
  426          */
  427         p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
  428         *(mtod(m, struct in_addr *)) = *p--;
  429 
  430         /*
  431          * Copy option fields and padding (nop) to mbuf.
  432          */
  433         opts->ip_srcrt.nop = IPOPT_NOP;
  434         opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
  435         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
  436             &(opts->ip_srcrt.nop), OPTSIZ);
  437         q = (struct in_addr *)(mtod(m, caddr_t) +
  438             sizeof(struct in_addr) + OPTSIZ);
  439 #undef OPTSIZ
  440         /*
  441          * Record return path as an IP source route, reversing the path
  442          * (pointers are now aligned).
  443          */
  444         while (p >= opts->ip_srcrt.route) {
  445                 *q++ = *p--;
  446         }
  447         /*
  448          * Last hop goes to final destination.
  449          */
  450         *q = opts->ip_srcrt.dst;
  451         m_tag_delete(m0, (struct m_tag *)opts);
  452         return (m);
  453 }
  454 
  455 /*
  456  * Strip out IP options, at higher level protocol in the kernel.  Second
  457  * argument is buffer to which options will be moved, and return value is
  458  * their length.
  459  *
  460  * XXX should be deleted; last arg currently ignored.
  461  */
  462 void
  463 ip_stripoptions(struct mbuf *m, struct mbuf *mopt)
  464 {
  465         int i;
  466         struct ip *ip = mtod(m, struct ip *);
  467         caddr_t opts;
  468         int olen;
  469 
  470         olen = (ip->ip_hl << 2) - sizeof (struct ip);
  471         opts = (caddr_t)(ip + 1);
  472         i = m->m_len - (sizeof (struct ip) + olen);
  473         bcopy(opts + olen, opts, (unsigned)i);
  474         m->m_len -= olen;
  475         if (m->m_flags & M_PKTHDR)
  476                 m->m_pkthdr.len -= olen;
  477         ip->ip_v = IPVERSION;
  478         ip->ip_hl = sizeof(struct ip) >> 2;
  479 }
  480 
  481 /*
  482  * Insert IP options into preformed packet.  Adjust IP destination as
  483  * required for IP source routing, as indicated by a non-zero in_addr at the
  484  * start of the options.
  485  *
  486  * XXX This routine assumes that the packet has no options in place.
  487  */
  488 struct mbuf *
  489 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
  490 {
  491         struct ipoption *p = mtod(opt, struct ipoption *);
  492         struct mbuf *n;
  493         struct ip *ip = mtod(m, struct ip *);
  494         unsigned optlen;
  495 
  496         optlen = opt->m_len - sizeof(p->ipopt_dst);
  497         if (optlen + ip->ip_len > IP_MAXPACKET) {
  498                 *phlen = 0;
  499                 return (m);             /* XXX should fail */
  500         }
  501         if (p->ipopt_dst.s_addr)
  502                 ip->ip_dst = p->ipopt_dst;
  503         if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
  504                 MGETHDR(n, M_DONTWAIT, MT_DATA);
  505                 if (n == NULL) {
  506                         *phlen = 0;
  507                         return (m);
  508                 }
  509                 M_MOVE_PKTHDR(n, m);
  510                 n->m_pkthdr.rcvif = NULL;
  511                 n->m_pkthdr.len += optlen;
  512                 m->m_len -= sizeof(struct ip);
  513                 m->m_data += sizeof(struct ip);
  514                 n->m_next = m;
  515                 m = n;
  516                 m->m_len = optlen + sizeof(struct ip);
  517                 m->m_data += max_linkhdr;
  518                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
  519         } else {
  520                 m->m_data -= optlen;
  521                 m->m_len += optlen;
  522                 m->m_pkthdr.len += optlen;
  523                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
  524         }
  525         ip = mtod(m, struct ip *);
  526         bcopy(p->ipopt_list, ip + 1, optlen);
  527         *phlen = sizeof(struct ip) + optlen;
  528         ip->ip_v = IPVERSION;
  529         ip->ip_hl = *phlen >> 2;
  530         ip->ip_len += optlen;
  531         return (m);
  532 }
  533 
  534 /*
  535  * Copy options from ip to jp, omitting those not copied during
  536  * fragmentation.
  537  */
  538 int
  539 ip_optcopy(struct ip *ip, struct ip *jp)
  540 {
  541         u_char *cp, *dp;
  542         int opt, optlen, cnt;
  543 
  544         cp = (u_char *)(ip + 1);
  545         dp = (u_char *)(jp + 1);
  546         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
  547         for (; cnt > 0; cnt -= optlen, cp += optlen) {
  548                 opt = cp[0];
  549                 if (opt == IPOPT_EOL)
  550                         break;
  551                 if (opt == IPOPT_NOP) {
  552                         /* Preserve for IP mcast tunnel's LSRR alignment. */
  553                         *dp++ = IPOPT_NOP;
  554                         optlen = 1;
  555                         continue;
  556                 }
  557 
  558                 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
  559                     ("ip_optcopy: malformed ipv4 option"));
  560                 optlen = cp[IPOPT_OLEN];
  561                 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
  562                     ("ip_optcopy: malformed ipv4 option"));
  563 
  564                 /* Bogus lengths should have been caught by ip_dooptions. */
  565                 if (optlen > cnt)
  566                         optlen = cnt;
  567                 if (IPOPT_COPIED(opt)) {
  568                         bcopy(cp, dp, optlen);
  569                         dp += optlen;
  570                 }
  571         }
  572         for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
  573                 *dp++ = IPOPT_EOL;
  574         return (optlen);
  575 }
  576 
  577 /*
  578  * Set up IP options in pcb for insertion in output packets.  Store in mbuf
  579  * with pointer in pcbopt, adding pseudo-option with destination address if
  580  * source routed.
  581  */
  582 int
  583 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
  584 {
  585         int cnt, optlen;
  586         u_char *cp;
  587         struct mbuf **pcbopt;
  588         u_char opt;
  589 
  590         INP_WLOCK_ASSERT(inp);
  591 
  592         pcbopt = &inp->inp_options;
  593 
  594         /* turn off any old options */
  595         if (*pcbopt)
  596                 (void)m_free(*pcbopt);
  597         *pcbopt = 0;
  598         if (m == NULL || m->m_len == 0) {
  599                 /*
  600                  * Only turning off any previous options.
  601                  */
  602                 if (m != NULL)
  603                         (void)m_free(m);
  604                 return (0);
  605         }
  606 
  607         if (m->m_len % sizeof(int32_t))
  608                 goto bad;
  609         /*
  610          * IP first-hop destination address will be stored before actual
  611          * options; move other options back and clear it when none present.
  612          */
  613         if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
  614                 goto bad;
  615         cnt = m->m_len;
  616         m->m_len += sizeof(struct in_addr);
  617         cp = mtod(m, u_char *) + sizeof(struct in_addr);
  618         bcopy(mtod(m, void *), cp, (unsigned)cnt);
  619         bzero(mtod(m, void *), sizeof(struct in_addr));
  620 
  621         for (; cnt > 0; cnt -= optlen, cp += optlen) {
  622                 opt = cp[IPOPT_OPTVAL];
  623                 if (opt == IPOPT_EOL)
  624                         break;
  625                 if (opt == IPOPT_NOP)
  626                         optlen = 1;
  627                 else {
  628                         if (cnt < IPOPT_OLEN + sizeof(*cp))
  629                                 goto bad;
  630                         optlen = cp[IPOPT_OLEN];
  631                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
  632                                 goto bad;
  633                 }
  634                 switch (opt) {
  635 
  636                 default:
  637                         break;
  638 
  639                 case IPOPT_LSRR:
  640                 case IPOPT_SSRR:
  641                         /*
  642                          * User process specifies route as:
  643                          *
  644                          *      ->A->B->C->D
  645                          *
  646                          * D must be our final destination (but we can't
  647                          * check that since we may not have connected yet).
  648                          * A is first hop destination, which doesn't appear
  649                          * in actual IP option, but is stored before the
  650                          * options.
  651                          */
  652                         /* XXX-BZ PRIV_NETINET_SETHDROPTS? */
  653                         if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
  654                                 goto bad;
  655                         m->m_len -= sizeof(struct in_addr);
  656                         cnt -= sizeof(struct in_addr);
  657                         optlen -= sizeof(struct in_addr);
  658                         cp[IPOPT_OLEN] = optlen;
  659                         /*
  660                          * Move first hop before start of options.
  661                          */
  662                         bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
  663                             sizeof(struct in_addr));
  664                         /*
  665                          * Then copy rest of options back
  666                          * to close up the deleted entry.
  667                          */
  668                         bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
  669                             &cp[IPOPT_OFFSET+1],
  670                             (unsigned)cnt - (IPOPT_MINOFF - 1));
  671                         break;
  672                 }
  673         }
  674         if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
  675                 goto bad;
  676         *pcbopt = m;
  677         return (0);
  678 
  679 bad:
  680         (void)m_free(m);
  681         return (EINVAL);
  682 }

Cache object: 1bca0a8c610f1dcef8501cb79871da91


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