The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/netipsec/ipsec_input.c

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    1 /*      $FreeBSD: releng/9.0/sys/netipsec/ipsec_input.c 223637 2011-06-28 11:57:25Z bz $        */
    2 /*      $OpenBSD: ipsec_input.c,v 1.63 2003/02/20 18:35:43 deraadt Exp $        */
    3 /*-
    4  * The authors of this code are John Ioannidis (ji@tla.org),
    5  * Angelos D. Keromytis (kermit@csd.uch.gr) and
    6  * Niels Provos (provos@physnet.uni-hamburg.de).
    7  *
    8  * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
    9  * in November 1995.
   10  *
   11  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
   12  * by Angelos D. Keromytis.
   13  *
   14  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
   15  * and Niels Provos.
   16  *
   17  * Additional features in 1999 by Angelos D. Keromytis.
   18  *
   19  * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
   20  * Angelos D. Keromytis and Niels Provos.
   21  * Copyright (c) 2001, Angelos D. Keromytis.
   22  *
   23  * Permission to use, copy, and modify this software with or without fee
   24  * is hereby granted, provided that this entire notice is included in
   25  * all copies of any software which is or includes a copy or
   26  * modification of this software.
   27  * You may use this code under the GNU public license if you so wish. Please
   28  * contribute changes back to the authors under this freer than GPL license
   29  * so that we may further the use of strong encryption without limitations to
   30  * all.
   31  *
   32  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
   33  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
   34  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
   35  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
   36  * PURPOSE.
   37  */
   38 
   39 /*
   40  * IPsec input processing.
   41  */
   42 
   43 #include "opt_inet.h"
   44 #include "opt_inet6.h"
   45 #include "opt_ipsec.h"
   46 #include "opt_enc.h"
   47 
   48 #include <sys/param.h>
   49 #include <sys/systm.h>
   50 #include <sys/malloc.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/domain.h>
   53 #include <sys/protosw.h>
   54 #include <sys/socket.h>
   55 #include <sys/errno.h>
   56 #include <sys/syslog.h>
   57 
   58 #include <net/if.h>
   59 #include <net/pfil.h>
   60 #include <net/route.h>
   61 #include <net/netisr.h>
   62 #include <net/vnet.h>
   63 
   64 #include <netinet/in.h>
   65 #include <netinet/in_systm.h>
   66 #include <netinet/ip.h>
   67 #include <netinet/ip_var.h>
   68 #include <netinet/in_var.h>
   69 
   70 #include <netinet/ip6.h>
   71 #ifdef INET6
   72 #include <netinet6/ip6_var.h>
   73 #endif
   74 #include <netinet/in_pcb.h>
   75 #ifdef INET6
   76 #include <netinet/icmp6.h>
   77 #endif
   78 
   79 #include <netipsec/ipsec.h>
   80 #ifdef INET6
   81 #include <netipsec/ipsec6.h>
   82 #endif
   83 #include <netipsec/ah_var.h>
   84 #include <netipsec/esp.h>
   85 #include <netipsec/esp_var.h>
   86 #include <netipsec/ipcomp_var.h>
   87 
   88 #include <netipsec/key.h>
   89 #include <netipsec/keydb.h>
   90 
   91 #include <netipsec/xform.h>
   92 #include <netinet6/ip6protosw.h>
   93 
   94 #include <machine/in_cksum.h>
   95 #include <machine/stdarg.h>
   96 
   97 #ifdef DEV_ENC
   98 #include <net/if_enc.h>
   99 #endif
  100 
  101 
  102 #define IPSEC_ISTAT(p,x,y,z) ((p) == IPPROTO_ESP ? (x)++ : \
  103                             (p) == IPPROTO_AH ? (y)++ : (z)++)
  104 
  105 #ifdef INET
  106 static void ipsec4_common_ctlinput(int, struct sockaddr *, void *, int);
  107 #endif
  108 
  109 /*
  110  * ipsec_common_input gets called when an IPsec-protected packet
  111  * is received by IPv4 or IPv6.  Its job is to find the right SA
  112  * and call the appropriate transform.  The transform callback
  113  * takes care of further processing (like ingress filtering).
  114  */
  115 static int
  116 ipsec_common_input(struct mbuf *m, int skip, int protoff, int af, int sproto)
  117 {
  118         union sockaddr_union dst_address;
  119         struct secasvar *sav;
  120         u_int32_t spi;
  121         int error;
  122 #ifdef INET
  123 #ifdef IPSEC_NAT_T
  124         struct m_tag *tag;
  125 #endif
  126 #endif
  127 
  128         IPSEC_ISTAT(sproto, V_espstat.esps_input, V_ahstat.ahs_input,
  129                 V_ipcompstat.ipcomps_input);
  130 
  131         IPSEC_ASSERT(m != NULL, ("null packet"));
  132 
  133         IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
  134                 sproto == IPPROTO_IPCOMP,
  135                 ("unexpected security protocol %u", sproto));
  136 
  137         if ((sproto == IPPROTO_ESP && !V_esp_enable) ||
  138             (sproto == IPPROTO_AH && !V_ah_enable) ||
  139             (sproto == IPPROTO_IPCOMP && !V_ipcomp_enable)) {
  140                 m_freem(m);
  141                 IPSEC_ISTAT(sproto, V_espstat.esps_pdrops, V_ahstat.ahs_pdrops,
  142                     V_ipcompstat.ipcomps_pdrops);
  143                 return EOPNOTSUPP;
  144         }
  145 
  146         if (m->m_pkthdr.len - skip < 2 * sizeof (u_int32_t)) {
  147                 m_freem(m);
  148                 IPSEC_ISTAT(sproto, V_espstat.esps_hdrops, V_ahstat.ahs_hdrops,
  149                     V_ipcompstat.ipcomps_hdrops);
  150                 DPRINTF(("%s: packet too small\n", __func__));
  151                 return EINVAL;
  152         }
  153 
  154         /* Retrieve the SPI from the relevant IPsec header */
  155         if (sproto == IPPROTO_ESP)
  156                 m_copydata(m, skip, sizeof(u_int32_t), (caddr_t) &spi);
  157         else if (sproto == IPPROTO_AH)
  158                 m_copydata(m, skip + sizeof(u_int32_t), sizeof(u_int32_t),
  159                     (caddr_t) &spi);
  160         else if (sproto == IPPROTO_IPCOMP) {
  161                 u_int16_t cpi;
  162                 m_copydata(m, skip + sizeof(u_int16_t), sizeof(u_int16_t),
  163                     (caddr_t) &cpi);
  164                 spi = ntohl(htons(cpi));
  165         }
  166 
  167         /*
  168          * Find the SA and (indirectly) call the appropriate
  169          * kernel crypto routine. The resulting mbuf chain is a valid
  170          * IP packet ready to go through input processing.
  171          */
  172         bzero(&dst_address, sizeof (dst_address));
  173         dst_address.sa.sa_family = af;
  174         switch (af) {
  175 #ifdef INET
  176         case AF_INET:
  177                 dst_address.sin.sin_len = sizeof(struct sockaddr_in);
  178                 m_copydata(m, offsetof(struct ip, ip_dst),
  179                     sizeof(struct in_addr),
  180                     (caddr_t) &dst_address.sin.sin_addr);
  181 #ifdef IPSEC_NAT_T
  182                 /* Find the source port for NAT-T; see udp*_espdecap. */
  183                 tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS, NULL);
  184                 if (tag != NULL)
  185                         dst_address.sin.sin_port = ((u_int16_t *)(tag + 1))[1];
  186 #endif /* IPSEC_NAT_T */
  187                 break;
  188 #endif /* INET */
  189 #ifdef INET6
  190         case AF_INET6:
  191                 dst_address.sin6.sin6_len = sizeof(struct sockaddr_in6);
  192                 m_copydata(m, offsetof(struct ip6_hdr, ip6_dst),
  193                     sizeof(struct in6_addr),
  194                     (caddr_t) &dst_address.sin6.sin6_addr);
  195                 break;
  196 #endif /* INET6 */
  197         default:
  198                 DPRINTF(("%s: unsupported protocol family %u\n", __func__, af));
  199                 m_freem(m);
  200                 IPSEC_ISTAT(sproto, V_espstat.esps_nopf, V_ahstat.ahs_nopf,
  201                     V_ipcompstat.ipcomps_nopf);
  202                 return EPFNOSUPPORT;
  203         }
  204 
  205         /* NB: only pass dst since key_allocsa follows RFC2401 */
  206         sav = KEY_ALLOCSA(&dst_address, sproto, spi);
  207         if (sav == NULL) {
  208                 DPRINTF(("%s: no key association found for SA %s/%08lx/%u\n",
  209                           __func__, ipsec_address(&dst_address),
  210                           (u_long) ntohl(spi), sproto));
  211                 IPSEC_ISTAT(sproto, V_espstat.esps_notdb, V_ahstat.ahs_notdb,
  212                     V_ipcompstat.ipcomps_notdb);
  213                 m_freem(m);
  214                 return ENOENT;
  215         }
  216 
  217         if (sav->tdb_xform == NULL) {
  218                 DPRINTF(("%s: attempted to use uninitialized SA %s/%08lx/%u\n",
  219                          __func__, ipsec_address(&dst_address),
  220                          (u_long) ntohl(spi), sproto));
  221                 IPSEC_ISTAT(sproto, V_espstat.esps_noxform, V_ahstat.ahs_noxform,
  222                     V_ipcompstat.ipcomps_noxform);
  223                 KEY_FREESAV(&sav);
  224                 m_freem(m);
  225                 return ENXIO;
  226         }
  227 
  228         /*
  229          * Call appropriate transform and return -- callback takes care of
  230          * everything else.
  231          */
  232         error = (*sav->tdb_xform->xf_input)(m, sav, skip, protoff);
  233         KEY_FREESAV(&sav);
  234         return error;
  235 }
  236 
  237 #ifdef INET
  238 /*
  239  * Common input handler for IPv4 AH, ESP, and IPCOMP.
  240  */
  241 int
  242 ipsec4_common_input(struct mbuf *m, ...)
  243 {
  244         va_list ap;
  245         int off, nxt;
  246 
  247         va_start(ap, m);
  248         off = va_arg(ap, int);
  249         nxt = va_arg(ap, int);
  250         va_end(ap);
  251 
  252         return ipsec_common_input(m, off, offsetof(struct ip, ip_p),
  253                                   AF_INET, nxt);
  254 }
  255 
  256 void
  257 ah4_input(struct mbuf *m, int off)
  258 {
  259         ipsec4_common_input(m, off, IPPROTO_AH);
  260 }
  261 void
  262 ah4_ctlinput(int cmd, struct sockaddr *sa, void *v)
  263 {
  264         if (sa->sa_family == AF_INET &&
  265             sa->sa_len == sizeof(struct sockaddr_in))
  266                 ipsec4_common_ctlinput(cmd, sa, v, IPPROTO_AH);
  267 }
  268 
  269 void
  270 esp4_input(struct mbuf *m, int off)
  271 {
  272         ipsec4_common_input(m, off, IPPROTO_ESP);
  273 }
  274 void
  275 esp4_ctlinput(int cmd, struct sockaddr *sa, void *v)
  276 {
  277         if (sa->sa_family == AF_INET &&
  278             sa->sa_len == sizeof(struct sockaddr_in))
  279                 ipsec4_common_ctlinput(cmd, sa, v, IPPROTO_ESP);
  280 }
  281 
  282 void
  283 ipcomp4_input(struct mbuf *m, int off)
  284 {
  285         ipsec4_common_input(m, off, IPPROTO_IPCOMP);
  286 }
  287 
  288 /*
  289  * IPsec input callback for INET protocols.
  290  * This routine is called as the transform callback.
  291  * Takes care of filtering and other sanity checks on
  292  * the processed packet.
  293  */
  294 int
  295 ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav,
  296                         int skip, int protoff, struct m_tag *mt)
  297 {
  298         int prot, af, sproto;
  299         struct ip *ip;
  300         struct m_tag *mtag;
  301         struct tdb_ident *tdbi;
  302         struct secasindex *saidx;
  303         int error;
  304 #ifdef INET6
  305 #ifdef notyet
  306         char ip6buf[INET6_ADDRSTRLEN];
  307 #endif
  308 #endif
  309 
  310         IPSEC_ASSERT(m != NULL, ("null mbuf"));
  311         IPSEC_ASSERT(sav != NULL, ("null SA"));
  312         IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
  313         saidx = &sav->sah->saidx;
  314         af = saidx->dst.sa.sa_family;
  315         IPSEC_ASSERT(af == AF_INET, ("unexpected af %u", af));
  316         sproto = saidx->proto;
  317         IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
  318                 sproto == IPPROTO_IPCOMP,
  319                 ("unexpected security protocol %u", sproto));
  320 
  321         /* Sanity check */
  322         if (m == NULL) {
  323                 DPRINTF(("%s: null mbuf", __func__));
  324                 IPSEC_ISTAT(sproto, V_espstat.esps_badkcr, V_ahstat.ahs_badkcr,
  325                     V_ipcompstat.ipcomps_badkcr);
  326                 KEY_FREESAV(&sav);
  327                 return EINVAL;
  328         }
  329 
  330         if (skip != 0) {
  331                 /* Fix IPv4 header */
  332                 if (m->m_len < skip && (m = m_pullup(m, skip)) == NULL) {
  333                         DPRINTF(("%s: processing failed for SA %s/%08lx\n",
  334                             __func__, ipsec_address(&sav->sah->saidx.dst),
  335                             (u_long) ntohl(sav->spi)));
  336                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops, V_ahstat.ahs_hdrops,
  337                             V_ipcompstat.ipcomps_hdrops);
  338                         error = ENOBUFS;
  339                         goto bad;
  340                 }
  341 
  342                 ip = mtod(m, struct ip *);
  343                 ip->ip_len = htons(m->m_pkthdr.len);
  344                 ip->ip_off = htons(ip->ip_off);
  345                 ip->ip_sum = 0;
  346                 ip->ip_sum = in_cksum(m, ip->ip_hl << 2);
  347         } else {
  348                 ip = mtod(m, struct ip *);
  349         }
  350         prot = ip->ip_p;
  351 
  352 #ifdef notyet
  353         /* IP-in-IP encapsulation */
  354         if (prot == IPPROTO_IPIP) {
  355                 struct ip ipn;
  356 
  357                 if (m->m_pkthdr.len - skip < sizeof(struct ip)) {
  358                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops,
  359                             V_ahstat.ahs_hdrops,
  360                             V_ipcompstat.ipcomps_hdrops);
  361                         error = EINVAL;
  362                         goto bad;
  363                 }
  364                 /* ipn will now contain the inner IPv4 header */
  365                 m_copydata(m, ip->ip_hl << 2, sizeof(struct ip),
  366                     (caddr_t) &ipn);
  367 
  368                 /* XXX PROXY address isn't recorded in SAH */
  369                 /*
  370                  * Check that the inner source address is the same as
  371                  * the proxy address, if available.
  372                  */
  373                 if ((saidx->proxy.sa.sa_family == AF_INET &&
  374                     saidx->proxy.sin.sin_addr.s_addr !=
  375                     INADDR_ANY &&
  376                     ipn.ip_src.s_addr !=
  377                     saidx->proxy.sin.sin_addr.s_addr) ||
  378                     (saidx->proxy.sa.sa_family != AF_INET &&
  379                         saidx->proxy.sa.sa_family != 0)) {
  380 
  381                         DPRINTF(("%s: inner source address %s doesn't "
  382                             "correspond to expected proxy source %s, "
  383                             "SA %s/%08lx\n", __func__,
  384                             inet_ntoa4(ipn.ip_src),
  385                             ipsp_address(saidx->proxy),
  386                             ipsp_address(saidx->dst),
  387                             (u_long) ntohl(sav->spi)));
  388 
  389                         IPSEC_ISTAT(sproto, V_espstat.esps_pdrops,
  390                             V_ahstat.ahs_pdrops,
  391                             V_ipcompstat.ipcomps_pdrops);
  392                         error = EACCES;
  393                         goto bad;
  394                 }
  395         }
  396 #ifdef INET6
  397         /* IPv6-in-IP encapsulation. */
  398         if (prot == IPPROTO_IPV6) {
  399                 struct ip6_hdr ip6n;
  400 
  401                 if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) {
  402                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops,
  403                             V_ahstat.ahs_hdrops,
  404                             V_ipcompstat.ipcomps_hdrops);
  405                         error = EINVAL;
  406                         goto bad;
  407                 }
  408                 /* ip6n will now contain the inner IPv6 header. */
  409                 m_copydata(m, ip->ip_hl << 2, sizeof(struct ip6_hdr),
  410                     (caddr_t) &ip6n);
  411 
  412                 /*
  413                  * Check that the inner source address is the same as
  414                  * the proxy address, if available.
  415                  */
  416                 if ((saidx->proxy.sa.sa_family == AF_INET6 &&
  417                     !IN6_IS_ADDR_UNSPECIFIED(&saidx->proxy.sin6.sin6_addr) &&
  418                     !IN6_ARE_ADDR_EQUAL(&ip6n.ip6_src,
  419                         &saidx->proxy.sin6.sin6_addr)) ||
  420                     (saidx->proxy.sa.sa_family != AF_INET6 &&
  421                         saidx->proxy.sa.sa_family != 0)) {
  422 
  423                         DPRINTF(("%s: inner source address %s doesn't "
  424                             "correspond to expected proxy source %s, "
  425                             "SA %s/%08lx\n", __func__,
  426                             ip6_sprintf(ip6buf, &ip6n.ip6_src),
  427                             ipsec_address(&saidx->proxy),
  428                             ipsec_address(&saidx->dst),
  429                             (u_long) ntohl(sav->spi)));
  430 
  431                         IPSEC_ISTAT(sproto, V_espstat.esps_pdrops,
  432                             V_ahstat.ahs_pdrops,
  433                             V_ipcompstat.ipcomps_pdrops);
  434                         error = EACCES;
  435                         goto bad;
  436                 }
  437         }
  438 #endif /* INET6 */
  439 #endif /*XXX*/
  440 
  441         /*
  442          * Record what we've done to the packet (under what SA it was
  443          * processed). If we've been passed an mtag, it means the packet
  444          * was already processed by an ethernet/crypto combo card and
  445          * thus has a tag attached with all the right information, but
  446          * with a PACKET_TAG_IPSEC_IN_CRYPTO_DONE as opposed to
  447          * PACKET_TAG_IPSEC_IN_DONE type; in that case, just change the type.
  448          */
  449         if (mt == NULL && sproto != IPPROTO_IPCOMP) {
  450                 mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE,
  451                     sizeof(struct tdb_ident), M_NOWAIT);
  452                 if (mtag == NULL) {
  453                         DPRINTF(("%s: failed to get tag\n", __func__));
  454                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops,
  455                             V_ahstat.ahs_hdrops, V_ipcompstat.ipcomps_hdrops);
  456                         error = ENOMEM;
  457                         goto bad;
  458                 }
  459 
  460                 tdbi = (struct tdb_ident *)(mtag + 1);
  461                 bcopy(&saidx->dst, &tdbi->dst, saidx->dst.sa.sa_len);
  462                 tdbi->proto = sproto;
  463                 tdbi->spi = sav->spi;
  464                 /* Cache those two for enc(4) in xform_ipip. */
  465                 tdbi->alg_auth = sav->alg_auth;
  466                 tdbi->alg_enc = sav->alg_enc;
  467 
  468                 m_tag_prepend(m, mtag);
  469         } else if (mt != NULL) {
  470                 mt->m_tag_id = PACKET_TAG_IPSEC_IN_DONE;
  471                 /* XXX do we need to mark m_flags??? */
  472         }
  473 
  474         key_sa_recordxfer(sav, m);              /* record data transfer */
  475 
  476         m_addr_changed(m);
  477 
  478 #ifdef DEV_ENC
  479         encif->if_ipackets++;
  480         encif->if_ibytes += m->m_pkthdr.len;
  481 
  482         /*
  483          * Pass the mbuf to enc0 for bpf and pfil. We will filter the IPIP
  484          * packet later after it has been decapsulated.
  485          */
  486         ipsec_bpf(m, sav, AF_INET, ENC_IN|ENC_BEFORE);
  487 
  488         if (prot != IPPROTO_IPIP)
  489                 if ((error = ipsec_filter(&m, PFIL_IN, ENC_IN|ENC_BEFORE)) != 0)
  490                         return (error);
  491 #endif
  492 
  493         /*
  494          * Re-dispatch via software interrupt.
  495          */
  496         if ((error = netisr_queue_src(NETISR_IP, (uintptr_t)sav->spi, m))) {
  497                 IPSEC_ISTAT(sproto, V_espstat.esps_qfull, V_ahstat.ahs_qfull,
  498                             V_ipcompstat.ipcomps_qfull);
  499 
  500                 DPRINTF(("%s: queue full; proto %u packet dropped\n",
  501                         __func__, sproto));
  502                 return error;
  503         }
  504         return 0;
  505 bad:
  506         m_freem(m);
  507         return error;
  508 }
  509 
  510 void
  511 ipsec4_common_ctlinput(int cmd, struct sockaddr *sa, void *v, int proto)
  512 {
  513         /* XXX nothing just yet */
  514 }
  515 #endif /* INET */
  516 
  517 #ifdef INET6
  518 /* IPv6 AH wrapper. */
  519 int
  520 ipsec6_common_input(struct mbuf **mp, int *offp, int proto)
  521 {
  522         int l = 0;
  523         int protoff;
  524         struct ip6_ext ip6e;
  525 
  526         if (*offp < sizeof(struct ip6_hdr)) {
  527                 DPRINTF(("%s: bad offset %u\n", __func__, *offp));
  528                 return IPPROTO_DONE;
  529         } else if (*offp == sizeof(struct ip6_hdr)) {
  530                 protoff = offsetof(struct ip6_hdr, ip6_nxt);
  531         } else {
  532                 /* Chase down the header chain... */
  533                 protoff = sizeof(struct ip6_hdr);
  534 
  535                 do {
  536                         protoff += l;
  537                         m_copydata(*mp, protoff, sizeof(ip6e),
  538                             (caddr_t) &ip6e);
  539 
  540                         if (ip6e.ip6e_nxt == IPPROTO_AH)
  541                                 l = (ip6e.ip6e_len + 2) << 2;
  542                         else
  543                                 l = (ip6e.ip6e_len + 1) << 3;
  544                         IPSEC_ASSERT(l > 0, ("l went zero or negative"));
  545                 } while (protoff + l < *offp);
  546 
  547                 /* Malformed packet check */
  548                 if (protoff + l != *offp) {
  549                         DPRINTF(("%s: bad packet header chain, protoff %u, "
  550                                 "l %u, off %u\n", __func__, protoff, l, *offp));
  551                         IPSEC_ISTAT(proto, V_espstat.esps_hdrops,
  552                                     V_ahstat.ahs_hdrops,
  553                                     V_ipcompstat.ipcomps_hdrops);
  554                         m_freem(*mp);
  555                         *mp = NULL;
  556                         return IPPROTO_DONE;
  557                 }
  558                 protoff += offsetof(struct ip6_ext, ip6e_nxt);
  559         }
  560         (void) ipsec_common_input(*mp, *offp, protoff, AF_INET6, proto);
  561         return IPPROTO_DONE;
  562 }
  563 
  564 /*
  565  * IPsec input callback, called by the transform callback. Takes care of
  566  * filtering and other sanity checks on the processed packet.
  567  */
  568 int
  569 ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip, int protoff,
  570     struct m_tag *mt)
  571 {
  572         int prot, af, sproto;
  573         struct ip6_hdr *ip6;
  574         struct m_tag *mtag;
  575         struct tdb_ident *tdbi;
  576         struct secasindex *saidx;
  577         int nxt;
  578         u_int8_t nxt8;
  579         int error, nest;
  580 #ifdef notyet
  581         char ip6buf[INET6_ADDRSTRLEN];
  582 #endif
  583 
  584         IPSEC_ASSERT(m != NULL, ("null mbuf"));
  585         IPSEC_ASSERT(sav != NULL, ("null SA"));
  586         IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
  587         saidx = &sav->sah->saidx;
  588         af = saidx->dst.sa.sa_family;
  589         IPSEC_ASSERT(af == AF_INET6, ("unexpected af %u", af));
  590         sproto = saidx->proto;
  591         IPSEC_ASSERT(sproto == IPPROTO_ESP || sproto == IPPROTO_AH ||
  592                 sproto == IPPROTO_IPCOMP,
  593                 ("unexpected security protocol %u", sproto));
  594 
  595         /* Sanity check */
  596         if (m == NULL) {
  597                 DPRINTF(("%s: null mbuf", __func__));
  598                 IPSEC_ISTAT(sproto, V_espstat.esps_badkcr, V_ahstat.ahs_badkcr,
  599                     V_ipcompstat.ipcomps_badkcr);
  600                 error = EINVAL;
  601                 goto bad;
  602         }
  603 
  604         /* Fix IPv6 header */
  605         if (m->m_len < sizeof(struct ip6_hdr) &&
  606             (m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
  607 
  608                 DPRINTF(("%s: processing failed for SA %s/%08lx\n",
  609                     __func__, ipsec_address(&sav->sah->saidx.dst),
  610                     (u_long) ntohl(sav->spi)));
  611 
  612                 IPSEC_ISTAT(sproto, V_espstat.esps_hdrops, V_ahstat.ahs_hdrops,
  613                     V_ipcompstat.ipcomps_hdrops);
  614                 error = EACCES;
  615                 goto bad;
  616         }
  617 
  618         ip6 = mtod(m, struct ip6_hdr *);
  619         ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
  620 
  621         /* Save protocol */
  622         m_copydata(m, protoff, 1, (unsigned char *) &prot);
  623 
  624 #ifdef notyet
  625 #ifdef INET
  626         /* IP-in-IP encapsulation */
  627         if (prot == IPPROTO_IPIP) {
  628                 struct ip ipn;
  629 
  630                 if (m->m_pkthdr.len - skip < sizeof(struct ip)) {
  631                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops,
  632                             V_ahstat.ahs_hdrops,
  633                             V_ipcompstat.ipcomps_hdrops);
  634                         error = EINVAL;
  635                         goto bad;
  636                 }
  637                 /* ipn will now contain the inner IPv4 header */
  638                 m_copydata(m, skip, sizeof(struct ip), (caddr_t) &ipn);
  639 
  640                 /*
  641                  * Check that the inner source address is the same as
  642                  * the proxy address, if available.
  643                  */
  644                 if ((saidx->proxy.sa.sa_family == AF_INET &&
  645                     saidx->proxy.sin.sin_addr.s_addr != INADDR_ANY &&
  646                     ipn.ip_src.s_addr != saidx->proxy.sin.sin_addr.s_addr) ||
  647                     (saidx->proxy.sa.sa_family != AF_INET &&
  648                         saidx->proxy.sa.sa_family != 0)) {
  649 
  650                         DPRINTF(("%s: inner source address %s doesn't "
  651                             "correspond to expected proxy source %s, "
  652                             "SA %s/%08lx\n", __func__,
  653                             inet_ntoa4(ipn.ip_src),
  654                             ipsec_address(&saidx->proxy),
  655                             ipsec_address(&saidx->dst),
  656                             (u_long) ntohl(sav->spi)));
  657 
  658                         IPSEC_ISTATsproto, (V_espstat.esps_pdrops,
  659                             V_ahstat.ahs_pdrops, V_ipcompstat.ipcomps_pdrops);
  660                         error = EACCES;
  661                         goto bad;
  662                 }
  663         }
  664 #endif /* INET */
  665 
  666         /* IPv6-in-IP encapsulation */
  667         if (prot == IPPROTO_IPV6) {
  668                 struct ip6_hdr ip6n;
  669 
  670                 if (m->m_pkthdr.len - skip < sizeof(struct ip6_hdr)) {
  671                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops,
  672                             V_ahstat.ahs_hdrops,
  673                             V_ipcompstat.ipcomps_hdrops);
  674                         error = EINVAL;
  675                         goto bad;
  676                 }
  677                 /* ip6n will now contain the inner IPv6 header. */
  678                 m_copydata(m, skip, sizeof(struct ip6_hdr),
  679                     (caddr_t) &ip6n);
  680 
  681                 /*
  682                  * Check that the inner source address is the same as
  683                  * the proxy address, if available.
  684                  */
  685                 if ((saidx->proxy.sa.sa_family == AF_INET6 &&
  686                     !IN6_IS_ADDR_UNSPECIFIED(&saidx->proxy.sin6.sin6_addr) &&
  687                     !IN6_ARE_ADDR_EQUAL(&ip6n.ip6_src,
  688                         &saidx->proxy.sin6.sin6_addr)) ||
  689                     (saidx->proxy.sa.sa_family != AF_INET6 &&
  690                         saidx->proxy.sa.sa_family != 0)) {
  691 
  692                         DPRINTF(("%s: inner source address %s doesn't "
  693                             "correspond to expected proxy source %s, "
  694                             "SA %s/%08lx\n", __func__,
  695                             ip6_sprintf(ip6buf, &ip6n.ip6_src),
  696                             ipsec_address(&saidx->proxy),
  697                             ipsec_address(&saidx->dst),
  698                             (u_long) ntohl(sav->spi)));
  699 
  700                         IPSEC_ISTAT(sproto, V_espstat.esps_pdrops,
  701                             V_ahstat.ahs_pdrops, V_ipcompstat.ipcomps_pdrops);
  702                         error = EACCES;
  703                         goto bad;
  704                 }
  705         }
  706 #endif /*XXX*/
  707 
  708         /*
  709          * Record what we've done to the packet (under what SA it was
  710          * processed). If we've been passed an mtag, it means the packet
  711          * was already processed by an ethernet/crypto combo card and
  712          * thus has a tag attached with all the right information, but
  713          * with a PACKET_TAG_IPSEC_IN_CRYPTO_DONE as opposed to
  714          * PACKET_TAG_IPSEC_IN_DONE type; in that case, just change the type.
  715          */
  716         if (mt == NULL && sproto != IPPROTO_IPCOMP) {
  717                 mtag = m_tag_get(PACKET_TAG_IPSEC_IN_DONE,
  718                     sizeof(struct tdb_ident), M_NOWAIT);
  719                 if (mtag == NULL) {
  720                         DPRINTF(("%s: failed to get tag\n", __func__));
  721                         IPSEC_ISTAT(sproto, V_espstat.esps_hdrops,
  722                             V_ahstat.ahs_hdrops, V_ipcompstat.ipcomps_hdrops);
  723                         error = ENOMEM;
  724                         goto bad;
  725                 }
  726 
  727                 tdbi = (struct tdb_ident *)(mtag + 1);
  728                 bcopy(&saidx->dst, &tdbi->dst, sizeof(union sockaddr_union));
  729                 tdbi->proto = sproto;
  730                 tdbi->spi = sav->spi;
  731                 /* Cache those two for enc(4) in xform_ipip. */
  732                 tdbi->alg_auth = sav->alg_auth;
  733                 tdbi->alg_enc = sav->alg_enc;
  734 
  735                 m_tag_prepend(m, mtag);
  736         } else {
  737                 if (mt != NULL)
  738                         mt->m_tag_id = PACKET_TAG_IPSEC_IN_DONE;
  739                 /* XXX do we need to mark m_flags??? */
  740         }
  741 
  742         key_sa_recordxfer(sav, m);
  743 
  744 #ifdef DEV_ENC
  745         encif->if_ipackets++;
  746         encif->if_ibytes += m->m_pkthdr.len;
  747 
  748         /*
  749          * Pass the mbuf to enc0 for bpf and pfil. We will filter the IPIP
  750          * packet later after it has been decapsulated.
  751          */
  752         ipsec_bpf(m, sav, AF_INET6, ENC_IN|ENC_BEFORE);
  753 
  754         /* XXX-BZ does not make sense. */
  755         if (prot != IPPROTO_IPIP)
  756                 if ((error = ipsec_filter(&m, PFIL_IN, ENC_IN|ENC_BEFORE)) != 0)
  757                         return (error);
  758 #endif
  759 
  760         /* Retrieve new protocol */
  761         m_copydata(m, protoff, sizeof(u_int8_t), (caddr_t) &nxt8);
  762 
  763         /*
  764          * See the end of ip6_input for this logic.
  765          * IPPROTO_IPV[46] case will be processed just like other ones
  766          */
  767         nest = 0;
  768         nxt = nxt8;
  769         while (nxt != IPPROTO_DONE) {
  770                 if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
  771                         V_ip6stat.ip6s_toomanyhdr++;
  772                         error = EINVAL;
  773                         goto bad;
  774                 }
  775 
  776                 /*
  777                  * Protection against faulty packet - there should be
  778                  * more sanity checks in header chain processing.
  779                  */
  780                 if (m->m_pkthdr.len < skip) {
  781                         V_ip6stat.ip6s_tooshort++;
  782                         in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
  783                         error = EINVAL;
  784                         goto bad;
  785                 }
  786                 /*
  787                  * Enforce IPsec policy checking if we are seeing last header.
  788                  * note that we do not visit this with protocols with pcb layer
  789                  * code - like udp/tcp/raw ip.
  790                  */
  791                 if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
  792                     ipsec6_in_reject(m, NULL)) {
  793                         error = EINVAL;
  794                         goto bad;
  795                 }
  796                 nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &skip, nxt);
  797         }
  798         return 0;
  799 bad:
  800         if (m)
  801                 m_freem(m);
  802         return error;
  803 }
  804 
  805 void
  806 esp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
  807 {
  808         struct ip6ctlparam *ip6cp = NULL;
  809         struct mbuf *m = NULL;
  810         struct ip6_hdr *ip6;
  811         int off;
  812 
  813         if (sa->sa_family != AF_INET6 ||
  814             sa->sa_len != sizeof(struct sockaddr_in6))
  815                 return;
  816         if ((unsigned)cmd >= PRC_NCMDS)
  817                 return;
  818 
  819         /* if the parameter is from icmp6, decode it. */
  820         if (d != NULL) {
  821                 ip6cp = (struct ip6ctlparam *)d;
  822                 m = ip6cp->ip6c_m;
  823                 ip6 = ip6cp->ip6c_ip6;
  824                 off = ip6cp->ip6c_off;
  825         } else {
  826                 m = NULL;
  827                 ip6 = NULL;
  828                 off = 0;        /* calm gcc */
  829         }
  830 
  831         if (ip6 != NULL) {
  832 
  833                 struct ip6ctlparam ip6cp1;
  834 
  835                 /*
  836                  * Notify the error to all possible sockets via pfctlinput2.
  837                  * Since the upper layer information (such as protocol type,
  838                  * source and destination ports) is embedded in the encrypted
  839                  * data and might have been cut, we can't directly call
  840                  * an upper layer ctlinput function. However, the pcbnotify
  841                  * function will consider source and destination addresses
  842                  * as well as the flow info value, and may be able to find
  843                  * some PCB that should be notified.
  844                  * Although pfctlinput2 will call esp6_ctlinput(), there is
  845                  * no possibility of an infinite loop of function calls,
  846                  * because we don't pass the inner IPv6 header.
  847                  */
  848                 bzero(&ip6cp1, sizeof(ip6cp1));
  849                 ip6cp1.ip6c_src = ip6cp->ip6c_src;
  850                 pfctlinput2(cmd, sa, (void *)&ip6cp1);
  851 
  852                 /*
  853                  * Then go to special cases that need ESP header information.
  854                  * XXX: We assume that when ip6 is non NULL,
  855                  * M and OFF are valid.
  856                  */
  857 
  858                 if (cmd == PRC_MSGSIZE) {
  859                         struct secasvar *sav;
  860                         u_int32_t spi;
  861                         int valid;
  862 
  863                         /* check header length before using m_copydata */
  864                         if (m->m_pkthdr.len < off + sizeof (struct esp))
  865                                 return;
  866                         m_copydata(m, off + offsetof(struct esp, esp_spi),
  867                                 sizeof(u_int32_t), (caddr_t) &spi);
  868                         /*
  869                          * Check to see if we have a valid SA corresponding to
  870                          * the address in the ICMP message payload.
  871                          */
  872                         sav = KEY_ALLOCSA((union sockaddr_union *)sa,
  873                                         IPPROTO_ESP, spi);
  874                         valid = (sav != NULL);
  875                         if (sav)
  876                                 KEY_FREESAV(&sav);
  877 
  878                         /* XXX Further validation? */
  879 
  880                         /*
  881                          * Depending on whether the SA is "valid" and
  882                          * routing table size (mtudisc_{hi,lo}wat), we will:
  883                          * - recalcurate the new MTU and create the
  884                          *   corresponding routing entry, or
  885                          * - ignore the MTU change notification.
  886                          */
  887                         icmp6_mtudisc_update(ip6cp, valid);
  888                 }
  889         } else {
  890                 /* we normally notify any pcb here */
  891         }
  892 }
  893 #endif /* INET6 */

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