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

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    1 /*      $NetBSD: xform_esp.c,v 1.18 2008/04/23 06:09:05 thorpej Exp $   */
    2 /*      $FreeBSD: src/sys/netipsec/xform_esp.c,v 1.2.2.1 2003/01/24 05:11:36 sam Exp $  */
    3 /*      $OpenBSD: ip_esp.c,v 1.69 2001/06/26 06:18:59 angelos Exp $ */
    4 
    5 /*
    6  * The authors of this code are John Ioannidis (ji@tla.org),
    7  * Angelos D. Keromytis (kermit@csd.uch.gr) and
    8  * Niels Provos (provos@physnet.uni-hamburg.de).
    9  *
   10  * The original version of this code was written by John Ioannidis
   11  * for BSD/OS in Athens, Greece, in November 1995.
   12  *
   13  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
   14  * by Angelos D. Keromytis.
   15  *
   16  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
   17  * and Niels Provos.
   18  *
   19  * Additional features in 1999 by Angelos D. Keromytis.
   20  *
   21  * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
   22  * Angelos D. Keromytis and Niels Provos.
   23  * Copyright (c) 2001 Angelos D. Keromytis.
   24  *
   25  * Permission to use, copy, and modify this software with or without fee
   26  * is hereby granted, provided that this entire notice is included in
   27  * all copies of any software which is or includes a copy or
   28  * modification of this software.
   29  * You may use this code under the GNU public license if you so wish. Please
   30  * contribute changes back to the authors under this freer than GPL license
   31  * so that we may further the use of strong encryption without limitations to
   32  * all.
   33  *
   34  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
   35  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
   36  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
   37  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
   38  * PURPOSE.
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __KERNEL_RCSID(0, "$NetBSD: xform_esp.c,v 1.18 2008/04/23 06:09:05 thorpej Exp $");
   43 
   44 #include "opt_inet.h"
   45 #ifdef __FreeBSD__
   46 #include "opt_inet6.h"
   47 #endif
   48 
   49 #include <sys/param.h>
   50 #include <sys/systm.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/socket.h>
   53 #include <sys/syslog.h>
   54 #include <sys/kernel.h>
   55 /*#include <sys/random.h>*/
   56 #include <sys/sysctl.h>
   57 
   58 #include <net/if.h>
   59 
   60 #include <netinet/in.h>
   61 #include <netinet/in_systm.h>
   62 #include <netinet/ip.h>
   63 #include <netinet/ip_ecn.h>
   64 #include <netinet/ip6.h>
   65 
   66 #include <net/route.h>
   67 #include <netipsec/ipsec.h>
   68 #include <netipsec/ipsec_private.h>
   69 #include <netipsec/ah.h>
   70 #include <netipsec/ah_var.h>
   71 #include <netipsec/esp.h>
   72 #include <netipsec/esp_var.h>
   73 #include <netipsec/xform.h>
   74 
   75 #ifdef INET6
   76 #include <netinet6/ip6_var.h>
   77 #include <netipsec/ipsec6.h>
   78 #  ifdef __FreeBSD__
   79 #  include <netinet6/ip6_ecn.h>
   80 #  endif
   81 #endif
   82 
   83 #include <netipsec/key.h>
   84 #include <netipsec/key_debug.h>
   85 
   86 #include <netipsec/ipsec_osdep.h>
   87 
   88 #include <opencrypto/cryptodev.h>
   89 #include <opencrypto/xform.h>
   90 
   91 percpu_t *espstat_percpu;
   92 
   93 int     esp_enable = 1;
   94 
   95 #ifdef __FreeBSD__
   96 SYSCTL_DECL(_net_inet_esp);
   97 SYSCTL_INT(_net_inet_esp, OID_AUTO,
   98         esp_enable,     CTLFLAG_RW,     &esp_enable,    0, "");
   99 SYSCTL_STRUCT(_net_inet_esp, IPSECCTL_STATS,
  100         stats,          CTLFLAG_RD,     &espstat,       espstat, "");
  101 #endif /* __FreeBSD__ */
  102 
  103 static  int esp_max_ivlen;              /* max iv length over all algorithms */
  104 
  105 static int esp_input_cb(struct cryptop *op);
  106 static int esp_output_cb(struct cryptop *crp);
  107 
  108 /*
  109  * NB: this is public for use by the PF_KEY support.
  110  * NB: if you add support here; be sure to add code to esp_attach below!
  111  */
  112 struct enc_xform *
  113 esp_algorithm_lookup(int alg)
  114 {
  115         if (alg >= ESP_ALG_MAX)
  116                 return NULL;
  117         switch (alg) {
  118         case SADB_EALG_DESCBC:
  119                 return &enc_xform_des;
  120         case SADB_EALG_3DESCBC:
  121                 return &enc_xform_3des;
  122         case SADB_X_EALG_AES:
  123                 return &enc_xform_rijndael128;
  124         case SADB_X_EALG_BLOWFISHCBC:
  125                 return &enc_xform_blf;
  126         case SADB_X_EALG_CAST128CBC:
  127                 return &enc_xform_cast5;
  128         case SADB_X_EALG_SKIPJACK:
  129                 return &enc_xform_skipjack;
  130         case SADB_EALG_NULL:
  131                 return &enc_xform_null;
  132         }
  133         return NULL;
  134 }
  135 
  136 size_t
  137 esp_hdrsiz(struct secasvar *sav)
  138 {
  139         size_t size;
  140 
  141         if (sav != NULL) {
  142                 /*XXX not right for null algorithm--does it matter??*/
  143                 IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
  144                         ("esp_hdrsiz: SA with null xform"));
  145                 if (sav->flags & SADB_X_EXT_OLD)
  146                         size = sizeof (struct esp);
  147                 else
  148                         size = sizeof (struct newesp);
  149                 size += sav->tdb_encalgxform->blocksize + 9;
  150                 /*XXX need alg check???*/
  151                 if (sav->tdb_authalgxform != NULL && sav->replay)
  152                         size += ah_hdrsiz(sav);
  153         } else {
  154                 /*
  155                  *   base header size
  156                  * + max iv length for CBC mode
  157                  * + max pad length
  158                  * + sizeof (pad length field)
  159                  * + sizeof (next header field)
  160                  * + max icv supported.
  161                  */
  162                 size = sizeof (struct newesp) + esp_max_ivlen + 9 + 16;
  163         }
  164         return size;
  165 }
  166 
  167 /*
  168  * esp_init() is called when an SPI is being set up.
  169  */
  170 static int
  171 esp_init(struct secasvar *sav, struct xformsw *xsp)
  172 {
  173         struct enc_xform *txform;
  174         struct cryptoini cria, crie;
  175         int keylen;
  176         int error;
  177 
  178         txform = esp_algorithm_lookup(sav->alg_enc);
  179         if (txform == NULL) {
  180                 DPRINTF(("esp_init: unsupported encryption algorithm %d\n",
  181                         sav->alg_enc));
  182                 return EINVAL;
  183         }
  184         if (sav->key_enc == NULL) {
  185                 DPRINTF(("esp_init: no encoding key for %s algorithm\n",
  186                          txform->name));
  187                 return EINVAL;
  188         }
  189         if ((sav->flags&(SADB_X_EXT_OLD|SADB_X_EXT_IV4B)) == SADB_X_EXT_IV4B) {
  190                 DPRINTF(("esp_init: 4-byte IV not supported with protocol\n"));
  191                 return EINVAL;
  192         }
  193         keylen = _KEYLEN(sav->key_enc);
  194         if (txform->minkey > keylen || keylen > txform->maxkey) {
  195                 DPRINTF(("esp_init: invalid key length %u, must be in "
  196                         "the range [%u..%u] for algorithm %s\n",
  197                         keylen, txform->minkey, txform->maxkey,
  198                         txform->name));
  199                 return EINVAL;
  200         }
  201 
  202         /*
  203          * NB: The null xform needs a non-zero blocksize to keep the
  204          *      crypto code happy but if we use it to set ivlen then
  205          *      the ESP header will be processed incorrectly.  The
  206          *      compromise is to force it to zero here.
  207          */
  208         sav->ivlen = (txform == &enc_xform_null ? 0 : txform->blocksize);
  209         sav->iv = malloc(sav->ivlen, M_SECA, M_WAITOK);
  210         if (sav->iv == NULL) {
  211                 DPRINTF(("esp_init: no memory for IV\n"));
  212                 return EINVAL;
  213         }
  214         key_randomfill(sav->iv, sav->ivlen);    /*XXX*/
  215 
  216         /*
  217          * Setup AH-related state.
  218          */
  219         if (sav->alg_auth != 0) {
  220                 error = ah_init0(sav, xsp, &cria);
  221                 if (error)
  222                         return error;
  223         }
  224 
  225         /* NB: override anything set in ah_init0 */
  226         sav->tdb_xform = xsp;
  227         sav->tdb_encalgxform = txform;
  228 
  229         /* Initialize crypto session. */
  230         bzero(&crie, sizeof (crie));
  231         crie.cri_alg = sav->tdb_encalgxform->type;
  232         crie.cri_klen = _KEYBITS(sav->key_enc);
  233         crie.cri_key = _KEYBUF(sav->key_enc);
  234         /* XXX Rounds ? */
  235 
  236         mutex_spin_enter(&crypto_mtx);
  237         if (sav->tdb_authalgxform && sav->tdb_encalgxform) {
  238                 /* init both auth & enc */
  239                 crie.cri_next = &cria;
  240                 error = crypto_newsession(&sav->tdb_cryptoid,
  241                                           &crie, crypto_support);
  242         } else if (sav->tdb_encalgxform) {
  243                 error = crypto_newsession(&sav->tdb_cryptoid,
  244                                           &crie, crypto_support);
  245         } else if (sav->tdb_authalgxform) {
  246                 error = crypto_newsession(&sav->tdb_cryptoid,
  247                                           &cria, crypto_support);
  248         } else {
  249                 /* XXX cannot happen? */
  250                 DPRINTF(("esp_init: no encoding OR authentication xform!\n"));
  251                 error = EINVAL;
  252         }
  253         mutex_spin_exit(&crypto_mtx);
  254         return error;
  255 }
  256 
  257 /*
  258  * Paranoia.
  259  */
  260 static int
  261 esp_zeroize(struct secasvar *sav)
  262 {
  263         /* NB: ah_zerorize free's the crypto session state */
  264         int error = ah_zeroize(sav);
  265 
  266         if (sav->key_enc)
  267                 bzero(_KEYBUF(sav->key_enc), _KEYLEN(sav->key_enc));
  268         /* NB: sav->iv is freed elsewhere, even though we malloc it! */
  269         sav->tdb_encalgxform = NULL;
  270         sav->tdb_xform = NULL;
  271         return error;
  272 }
  273 
  274 /*
  275  * ESP input processing, called (eventually) through the protocol switch.
  276  */
  277 static int
  278 esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
  279 {
  280         struct auth_hash *esph;
  281         struct enc_xform *espx;
  282         struct tdb_ident *tdbi;
  283         struct tdb_crypto *tc;
  284         int plen, alen, hlen;
  285         struct m_tag *mtag;
  286         struct newesp *esp;
  287 
  288         struct cryptodesc *crde;
  289         struct cryptop *crp;
  290 
  291         IPSEC_SPLASSERT_SOFTNET("esp_input");
  292 
  293         IPSEC_ASSERT(sav != NULL, ("esp_input: null SA"));
  294         IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
  295                 ("esp_input: null encoding xform"));
  296         IPSEC_ASSERT((skip&3) == 0 && (m->m_pkthdr.len&3) == 0,
  297                 ("esp_input: misaligned packet, skip %u pkt len %u",
  298                         skip, m->m_pkthdr.len));
  299 
  300         /* XXX don't pullup, just copy header */
  301         IP6_EXTHDR_GET(esp, struct newesp *, m, skip, sizeof (struct newesp));
  302 
  303         esph = sav->tdb_authalgxform;
  304         espx = sav->tdb_encalgxform;
  305 
  306         /* Determine the ESP header length */
  307         if (sav->flags & SADB_X_EXT_OLD)
  308                 hlen = sizeof (struct esp) + sav->ivlen;
  309         else
  310                 hlen = sizeof (struct newesp) + sav->ivlen;
  311         /* Authenticator hash size */
  312         alen = esph ? AH_HMAC_HASHLEN : 0;
  313 
  314         /*
  315          * Verify payload length is multiple of encryption algorithm
  316          * block size.
  317          *
  318          * NB: This works for the null algorithm because the blocksize
  319          *     is 4 and all packets must be 4-byte aligned regardless
  320          *     of the algorithm.
  321          */
  322         plen = m->m_pkthdr.len - (skip + hlen + alen);
  323         if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
  324                 DPRINTF(("esp_input: "
  325                     "payload of %d octets not a multiple of %d octets,"
  326                     "  SA %s/%08lx\n",
  327                     plen, espx->blocksize,
  328                     ipsec_address(&sav->sah->saidx.dst),
  329                     (u_long) ntohl(sav->spi)));
  330                 ESP_STATINC(ESP_STAT_BADILEN);
  331                 m_freem(m);
  332                 return EINVAL;
  333         }
  334 
  335         /*
  336          * Check sequence number.
  337          */
  338         if (esph && sav->replay && !ipsec_chkreplay(ntohl(esp->esp_seq), sav)) {
  339                 DPRINTF(("esp_input: packet replay check for %s\n",
  340                     ipsec_logsastr(sav)));      /*XXX*/
  341                 ESP_STATINC(ESP_STAT_REPLAY);
  342                 m_freem(m);
  343                 return ENOBUFS;         /*XXX*/
  344         }
  345 
  346         /* Update the counters */
  347         ESP_STATADD(ESP_STAT_IBYTES, m->m_pkthdr.len - skip - hlen - alen);
  348 
  349         /* Find out if we've already done crypto */
  350         for (mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, NULL);
  351              mtag != NULL;
  352              mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, mtag)) {
  353                 tdbi = (struct tdb_ident *) (mtag + 1);
  354                 if (tdbi->proto == sav->sah->saidx.proto &&
  355                     tdbi->spi == sav->spi &&
  356                     !bcmp(&tdbi->dst, &sav->sah->saidx.dst,
  357                           sizeof(union sockaddr_union)))
  358                         break;
  359         }
  360 
  361         /* Get crypto descriptors */
  362         crp = crypto_getreq(esph && espx ? 2 : 1);
  363         if (crp == NULL) {
  364                 DPRINTF(("esp_input: failed to acquire crypto descriptors\n"));
  365                 ESP_STATINC(ESP_STAT_CRYPTO);
  366                 m_freem(m);
  367                 return ENOBUFS;
  368         }
  369 
  370         /* Get IPsec-specific opaque pointer */
  371         if (esph == NULL || mtag != NULL)
  372                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  373                     M_XDATA, M_NOWAIT|M_ZERO);
  374         else
  375                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto) + alen,
  376                     M_XDATA, M_NOWAIT|M_ZERO);
  377         if (tc == NULL) {
  378                 crypto_freereq(crp);
  379                 DPRINTF(("esp_input: failed to allocate tdb_crypto\n"));
  380                 ESP_STATINC(ESP_STAT_CRYPTO);
  381                 m_freem(m);
  382                 return ENOBUFS;
  383         }
  384 
  385         tc->tc_ptr = mtag;
  386 
  387         if (esph) {
  388                 struct cryptodesc *crda = crp->crp_desc;
  389 
  390                 IPSEC_ASSERT(crda != NULL, ("esp_input: null ah crypto descriptor"));
  391 
  392                 /* Authentication descriptor */
  393                 crda->crd_skip = skip;
  394                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  395                 crda->crd_inject = m->m_pkthdr.len - alen;
  396 
  397                 crda->crd_alg = esph->type;
  398                 crda->crd_key = _KEYBUF(sav->key_auth);
  399                 crda->crd_klen = _KEYBITS(sav->key_auth);
  400 
  401                 /* Copy the authenticator */
  402                 if (mtag == NULL)
  403                         m_copydata(m, m->m_pkthdr.len - alen, alen,
  404                                       (tc + 1));
  405 
  406                 /* Chain authentication request */
  407                 crde = crda->crd_next;
  408         } else {
  409                 crde = crp->crp_desc;
  410         }
  411 
  412         /* Crypto operation descriptor */
  413         crp->crp_ilen = m->m_pkthdr.len; /* Total input length */
  414         crp->crp_flags = CRYPTO_F_IMBUF;
  415         crp->crp_buf = m;
  416         crp->crp_callback = esp_input_cb;
  417         crp->crp_sid = sav->tdb_cryptoid;
  418         crp->crp_opaque = tc;
  419 
  420         /* These are passed as-is to the callback */
  421         tc->tc_spi = sav->spi;
  422         tc->tc_dst = sav->sah->saidx.dst;
  423         tc->tc_proto = sav->sah->saidx.proto;
  424         tc->tc_protoff = protoff;
  425         tc->tc_skip = skip;
  426 
  427         /* Decryption descriptor */
  428         if (espx) {
  429                 IPSEC_ASSERT(crde != NULL, ("esp_input: null esp crypto descriptor"));
  430                 crde->crd_skip = skip + hlen;
  431                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  432                 crde->crd_inject = skip + hlen - sav->ivlen;
  433 
  434                 crde->crd_alg = espx->type;
  435                 crde->crd_key = _KEYBUF(sav->key_enc);
  436                 crde->crd_klen = _KEYBITS(sav->key_enc);
  437                 /* XXX Rounds ? */
  438         }
  439 
  440         if (mtag == NULL)
  441                 return crypto_dispatch(crp);
  442         else
  443                 return esp_input_cb(crp);
  444 }
  445 
  446 #ifdef INET6
  447 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag) do {              \
  448         if (saidx->dst.sa.sa_family == AF_INET6) {                           \
  449                 error = ipsec6_common_input_cb(m, sav, skip, protoff, mtag); \
  450         } else {                                                             \
  451                 error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag); \
  452         }                                                                    \
  453 } while (0)
  454 #else
  455 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag)                   \
  456         (error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag))
  457 #endif
  458 
  459 /*
  460  * ESP input callback from the crypto driver.
  461  */
  462 static int
  463 esp_input_cb(struct cryptop *crp)
  464 {
  465         u_int8_t lastthree[3], aalg[AH_HMAC_HASHLEN];
  466         int s, hlen, skip, protoff, error;
  467         struct mbuf *m;
  468         struct cryptodesc *crd;
  469         struct auth_hash *esph;
  470         struct enc_xform *espx;
  471         struct tdb_crypto *tc;
  472         struct m_tag *mtag;
  473         struct secasvar *sav;
  474         struct secasindex *saidx;
  475         void *ptr;
  476         u_int16_t dport = 0;
  477         u_int16_t sport = 0;
  478 #ifdef IPSEC_NAT_T
  479         struct m_tag * tag = NULL;
  480 #endif
  481 
  482         crd = crp->crp_desc;
  483         IPSEC_ASSERT(crd != NULL, ("esp_input_cb: null crypto descriptor!"));
  484 
  485         tc = (struct tdb_crypto *) crp->crp_opaque;
  486         IPSEC_ASSERT(tc != NULL, ("esp_input_cb: null opaque crypto data area!"));
  487         skip = tc->tc_skip;
  488         protoff = tc->tc_protoff;
  489         mtag = (struct m_tag *) tc->tc_ptr;
  490         m = (struct mbuf *) crp->crp_buf;
  491 
  492 #ifdef IPSEC_NAT_T
  493         /* find the source port for NAT-T */
  494         if ((tag = m_tag_find(m, PACKET_TAG_IPSEC_NAT_T_PORTS, NULL))) {
  495                 sport = ((u_int16_t *)(tag + 1))[0];
  496                 dport = ((u_int16_t *)(tag + 1))[1];
  497         }
  498 #endif
  499 
  500         s = splsoftnet();
  501 
  502         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi, sport, dport);
  503         if (sav == NULL) {
  504                 ESP_STATINC(ESP_STAT_NOTDB);
  505                 DPRINTF(("esp_input_cb: SA expired while in crypto "
  506                     "(SA %s/%08lx proto %u)\n", ipsec_address(&tc->tc_dst),
  507                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  508                 error = ENOBUFS;                /*XXX*/
  509                 goto bad;
  510         }
  511 
  512         saidx = &sav->sah->saidx;
  513         IPSEC_ASSERT(saidx->dst.sa.sa_family == AF_INET ||
  514                 saidx->dst.sa.sa_family == AF_INET6,
  515                 ("ah_input_cb: unexpected protocol family %u",
  516                  saidx->dst.sa.sa_family));
  517 
  518         esph = sav->tdb_authalgxform;
  519         espx = sav->tdb_encalgxform;
  520 
  521         /* Check for crypto errors */
  522         if (crp->crp_etype) {
  523                 /* Reset the session ID */
  524                 if (sav->tdb_cryptoid != 0)
  525                         sav->tdb_cryptoid = crp->crp_sid;
  526 
  527                 if (crp->crp_etype == EAGAIN) {
  528                         KEY_FREESAV(&sav);
  529                         splx(s);
  530                         return crypto_dispatch(crp);
  531                 }
  532 
  533                 ESP_STATINC(ESP_STAT_NOXFORM);
  534                 DPRINTF(("esp_input_cb: crypto error %d\n", crp->crp_etype));
  535                 error = crp->crp_etype;
  536                 goto bad;
  537         }
  538 
  539         /* Shouldn't happen... */
  540         if (m == NULL) {
  541                 ESP_STATINC(ESP_STAT_CRYPTO);
  542                 DPRINTF(("esp_input_cb: bogus returned buffer from crypto\n"));
  543                 error = EINVAL;
  544                 goto bad;
  545         }
  546         ESP_STATINC(ESP_STAT_HIST + sav->alg_enc);
  547 
  548         /* If authentication was performed, check now. */
  549         if (esph != NULL) {
  550                 /*
  551                  * If we have a tag, it means an IPsec-aware NIC did
  552                  * the verification for us.  Otherwise we need to
  553                  * check the authentication calculation.
  554                  */
  555                 AH_STATINC(AH_STAT_HIST + sav->alg_auth);
  556                 if (mtag == NULL) {
  557                         /* Copy the authenticator from the packet */
  558                         m_copydata(m, m->m_pkthdr.len - esph->authsize,
  559                                 esph->authsize, aalg);
  560 
  561                         ptr = (tc + 1);
  562 
  563                         /* Verify authenticator */
  564                         if (bcmp(ptr, aalg, esph->authsize) != 0) {
  565                                 DPRINTF(("esp_input_cb: "
  566                     "authentication hash mismatch for packet in SA %s/%08lx\n",
  567                                     ipsec_address(&saidx->dst),
  568                                     (u_long) ntohl(sav->spi)));
  569                                 ESP_STATINC(ESP_STAT_BADAUTH);
  570                                 error = EACCES;
  571                                 goto bad;
  572                         }
  573                 }
  574 
  575                 /* Remove trailing authenticator */
  576                 m_adj(m, -(esph->authsize));
  577         }
  578 
  579         /* Release the crypto descriptors */
  580         free(tc, M_XDATA), tc = NULL;
  581         crypto_freereq(crp), crp = NULL;
  582 
  583         /*
  584          * Packet is now decrypted.
  585          */
  586         m->m_flags |= M_DECRYPTED;
  587 
  588         /*
  589          * Update replay sequence number, if appropriate.
  590          */
  591         if (sav->replay) {
  592                 u_int32_t seq;
  593 
  594                 m_copydata(m, skip + offsetof(struct newesp, esp_seq),
  595                     sizeof (seq), &seq);
  596                 if (ipsec_updatereplay(ntohl(seq), sav)) {
  597                         DPRINTF(("%s: packet replay check for %s\n", __func__,
  598                             ipsec_logsastr(sav)));
  599                         ESP_STATINC(ESP_STAT_REPLAY);
  600                         error = ENOBUFS;
  601                         goto bad;
  602                 }
  603         }
  604 
  605         /* Determine the ESP header length */
  606         if (sav->flags & SADB_X_EXT_OLD)
  607                 hlen = sizeof (struct esp) + sav->ivlen;
  608         else
  609                 hlen = sizeof (struct newesp) + sav->ivlen;
  610 
  611         /* Remove the ESP header and IV from the mbuf. */
  612         error = m_striphdr(m, skip, hlen);
  613         if (error) {
  614                 ESP_STATINC(ESP_STAT_HDROPS);
  615                 DPRINTF(("esp_input_cb: bad mbuf chain, SA %s/%08lx\n",
  616                     ipsec_address(&sav->sah->saidx.dst),
  617                     (u_long) ntohl(sav->spi)));
  618                 goto bad;
  619         }
  620 
  621         /* Save the last three bytes of decrypted data */
  622         m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);
  623 
  624         /* Verify pad length */
  625         if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
  626                 ESP_STATINC(ESP_STAT_BADILEN);
  627                 DPRINTF(("esp_input_cb: invalid padding length %d "
  628                          "for %u byte packet in SA %s/%08lx\n",
  629                          lastthree[1], m->m_pkthdr.len - skip,
  630                          ipsec_address(&sav->sah->saidx.dst),
  631                          (u_long) ntohl(sav->spi)));
  632                 error = EINVAL;
  633                 goto bad;
  634         }
  635 
  636         /* Verify correct decryption by checking the last padding bytes */
  637         if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
  638                 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
  639                         ESP_STATINC(ESP_STAT_BADENC);
  640                         DPRINTF(("esp_input_cb: decryption failed "
  641                                 "for packet in SA %s/%08lx\n",
  642                                 ipsec_address(&sav->sah->saidx.dst),
  643                                 (u_long) ntohl(sav->spi)));
  644 DPRINTF(("esp_input_cb: %x %x\n", lastthree[0], lastthree[1]));
  645                         error = EINVAL;
  646                         goto bad;
  647                 }
  648         }
  649 
  650         /* Trim the mbuf chain to remove trailing authenticator and padding */
  651         m_adj(m, -(lastthree[1] + 2));
  652 
  653         /* Restore the Next Protocol field */
  654         m = m_copyback_cow(m, protoff, sizeof (u_int8_t), lastthree + 2,
  655                            M_DONTWAIT);
  656 
  657         if (m == NULL) {
  658                 ESP_STATINC(ESP_STAT_CRYPTO);
  659                 DPRINTF(("esp_input_cb: failed to allocate mbuf\n"));
  660                 error = ENOBUFS;
  661                 goto bad;
  662         }
  663 
  664         IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag);
  665 
  666         KEY_FREESAV(&sav);
  667         splx(s);
  668         return error;
  669 bad:
  670         if (sav)
  671                 KEY_FREESAV(&sav);
  672         splx(s);
  673         if (m != NULL)
  674                 m_freem(m);
  675         if (tc != NULL)
  676                 free(tc, M_XDATA);
  677         if (crp != NULL)
  678                 crypto_freereq(crp);
  679         return error;
  680 }
  681 
  682 /*
  683  * ESP output routine, called by ipsec[46]_process_packet().
  684  */
  685 static int
  686 esp_output(
  687     struct mbuf *m,
  688     struct ipsecrequest *isr,
  689     struct mbuf **mp,
  690     int skip,
  691     int protoff
  692 )
  693 {
  694         struct enc_xform *espx;
  695         struct auth_hash *esph;
  696         int hlen, rlen, plen, padding, blks, alen, i, roff;
  697         struct mbuf *mo = (struct mbuf *) NULL;
  698         struct tdb_crypto *tc;
  699         struct secasvar *sav;
  700         struct secasindex *saidx;
  701         unsigned char *pad;
  702         u_int8_t prot;
  703         int error, maxpacketsize;
  704 
  705         struct cryptodesc *crde = NULL, *crda = NULL;
  706         struct cryptop *crp;
  707 
  708         IPSEC_SPLASSERT_SOFTNET("esp_output");
  709 
  710         sav = isr->sav;
  711         IPSEC_ASSERT(sav != NULL, ("esp_output: null SA"));
  712         esph = sav->tdb_authalgxform;
  713         espx = sav->tdb_encalgxform;
  714         IPSEC_ASSERT(espx != NULL, ("esp_output: null encoding xform"));
  715 
  716         if (sav->flags & SADB_X_EXT_OLD)
  717                 hlen = sizeof (struct esp) + sav->ivlen;
  718         else
  719                 hlen = sizeof (struct newesp) + sav->ivlen;
  720 
  721         rlen = m->m_pkthdr.len - skip;  /* Raw payload length. */
  722         /*
  723          * NB: The null encoding transform has a blocksize of 4
  724          *     so that headers are properly aligned.
  725          */
  726         blks = espx->blocksize;         /* IV blocksize */
  727 
  728         /* XXX clamp padding length a la KAME??? */
  729         padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;
  730         plen = rlen + padding;          /* Padded payload length. */
  731 
  732         if (esph)
  733                 alen = AH_HMAC_HASHLEN;
  734         else
  735                 alen = 0;
  736 
  737         ESP_STATINC(ESP_STAT_OUTPUT);
  738 
  739         saidx = &sav->sah->saidx;
  740         /* Check for maximum packet size violations. */
  741         switch (saidx->dst.sa.sa_family) {
  742 #ifdef INET
  743         case AF_INET:
  744                 maxpacketsize = IP_MAXPACKET;
  745                 break;
  746 #endif /* INET */
  747 #ifdef INET6
  748         case AF_INET6:
  749                 maxpacketsize = IPV6_MAXPACKET;
  750                 break;
  751 #endif /* INET6 */
  752         default:
  753                 DPRINTF(("esp_output: unknown/unsupported protocol "
  754                     "family %d, SA %s/%08lx\n",
  755                     saidx->dst.sa.sa_family, ipsec_address(&saidx->dst),
  756                     (u_long) ntohl(sav->spi)));
  757                 ESP_STATINC(ESP_STAT_NOPF);
  758                 error = EPFNOSUPPORT;
  759                 goto bad;
  760         }
  761         if (skip + hlen + rlen + padding + alen > maxpacketsize) {
  762                 DPRINTF(("esp_output: packet in SA %s/%08lx got too big "
  763                     "(len %u, max len %u)\n",
  764                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi),
  765                     skip + hlen + rlen + padding + alen, maxpacketsize));
  766                 ESP_STATINC(ESP_STAT_TOOBIG);
  767                 error = EMSGSIZE;
  768                 goto bad;
  769         }
  770 
  771         /* Update the counters. */
  772         ESP_STATADD(ESP_STAT_OUTPUT, m->m_pkthdr.len - skip);
  773 
  774         m = m_clone(m);
  775         if (m == NULL) {
  776                 DPRINTF(("esp_output: cannot clone mbuf chain, SA %s/%08lx\n",
  777                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  778                 ESP_STATINC(ESP_STAT_HDROPS);
  779                 error = ENOBUFS;
  780                 goto bad;
  781         }
  782 
  783         /* Inject ESP header. */
  784         mo = m_makespace(m, skip, hlen, &roff);
  785         if (mo == NULL) {
  786                 DPRINTF(("esp_output: failed to inject %u byte ESP hdr for SA "
  787                     "%s/%08lx\n",
  788                     hlen, ipsec_address(&saidx->dst),
  789                     (u_long) ntohl(sav->spi)));
  790                 ESP_STATINC(ESP_STAT_HDROPS);   /* XXX diffs from openbsd */
  791                 error = ENOBUFS;
  792                 goto bad;
  793         }
  794 
  795         /* Initialize ESP header. */
  796         bcopy(&sav->spi, mtod(mo, char *) + roff, sizeof(u_int32_t));
  797         if (sav->replay) {
  798                 u_int32_t replay;
  799 
  800 #ifdef IPSEC_DEBUG
  801                 /* Emulate replay attack when ipsec_replay is TRUE. */
  802                 if (!ipsec_replay)
  803 #endif
  804                         sav->replay->count++;
  805 
  806                 replay = htonl(sav->replay->count);
  807                 bcopy(&replay,
  808                     mtod(mo,char *) + roff + sizeof(u_int32_t),
  809                     sizeof(u_int32_t));
  810         }
  811 
  812         /*
  813          * Add padding -- better to do it ourselves than use the crypto engine,
  814          * although if/when we support compression, we'd have to do that.
  815          */
  816         pad = (u_char *) m_pad(m, padding + alen);
  817         if (pad == NULL) {
  818                 DPRINTF(("esp_output: m_pad failed for SA %s/%08lx\n",
  819                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  820                 m = NULL;               /* NB: free'd by m_pad */
  821                 error = ENOBUFS;
  822                 goto bad;
  823         }
  824 
  825         /*
  826          * Add padding: random, zero, or self-describing.
  827          * XXX catch unexpected setting
  828          */
  829         switch (sav->flags & SADB_X_EXT_PMASK) {
  830         case SADB_X_EXT_PRAND:
  831                 (void) read_random(pad, padding - 2);
  832                 break;
  833         case SADB_X_EXT_PZERO:
  834                 bzero(pad, padding - 2);
  835                 break;
  836         case SADB_X_EXT_PSEQ:
  837                 for (i = 0; i < padding - 2; i++)
  838                         pad[i] = i+1;
  839                 break;
  840         }
  841 
  842         /* Fix padding length and Next Protocol in padding itself. */
  843         pad[padding - 2] = padding - 2;
  844         m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);
  845 
  846         /* Fix Next Protocol in IPv4/IPv6 header. */
  847         prot = IPPROTO_ESP;
  848         m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);
  849 
  850         /* Get crypto descriptors. */
  851         crp = crypto_getreq(esph && espx ? 2 : 1);
  852         if (crp == NULL) {
  853                 DPRINTF(("esp_output: failed to acquire crypto descriptors\n"));
  854                 ESP_STATINC(ESP_STAT_CRYPTO);
  855                 error = ENOBUFS;
  856                 goto bad;
  857         }
  858 
  859         if (espx) {
  860                 crde = crp->crp_desc;
  861                 crda = crde->crd_next;
  862 
  863                 /* Encryption descriptor. */
  864                 crde->crd_skip = skip + hlen;
  865                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  866                 crde->crd_flags = CRD_F_ENCRYPT;
  867                 crde->crd_inject = skip + hlen - sav->ivlen;
  868 
  869                 /* Encryption operation. */
  870                 crde->crd_alg = espx->type;
  871                 crde->crd_key = _KEYBUF(sav->key_enc);
  872                 crde->crd_klen = _KEYBITS(sav->key_enc);
  873                 /* XXX Rounds ? */
  874         } else
  875                 crda = crp->crp_desc;
  876 
  877         /* IPsec-specific opaque crypto info. */
  878         tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  879                 M_XDATA, M_NOWAIT|M_ZERO);
  880         if (tc == NULL) {
  881                 crypto_freereq(crp);
  882                 DPRINTF(("esp_output: failed to allocate tdb_crypto\n"));
  883                 ESP_STATINC(ESP_STAT_CRYPTO);
  884                 error = ENOBUFS;
  885                 goto bad;
  886         }
  887 
  888         /* Callback parameters */
  889         tc->tc_isr = isr;
  890         tc->tc_spi = sav->spi;
  891         tc->tc_dst = saidx->dst;
  892         tc->tc_proto = saidx->proto;
  893 
  894         /* Crypto operation descriptor. */
  895         crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
  896         crp->crp_flags = CRYPTO_F_IMBUF;
  897         crp->crp_buf = m;
  898         crp->crp_callback = esp_output_cb;
  899         crp->crp_opaque = tc;
  900         crp->crp_sid = sav->tdb_cryptoid;
  901 
  902         if (esph) {
  903                 /* Authentication descriptor. */
  904                 crda->crd_skip = skip;
  905                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  906                 crda->crd_inject = m->m_pkthdr.len - alen;
  907 
  908                 /* Authentication operation. */
  909                 crda->crd_alg = esph->type;
  910                 crda->crd_key = _KEYBUF(sav->key_auth);
  911                 crda->crd_klen = _KEYBITS(sav->key_auth);
  912         }
  913 
  914         return crypto_dispatch(crp);
  915 bad:
  916         if (m)
  917                 m_freem(m);
  918         return (error);
  919 }
  920 
  921 /*
  922  * ESP output callback from the crypto driver.
  923  */
  924 static int
  925 esp_output_cb(struct cryptop *crp)
  926 {
  927         struct tdb_crypto *tc;
  928         struct ipsecrequest *isr;
  929         struct secasvar *sav;
  930         struct mbuf *m;
  931         int s, err, error;
  932 
  933         tc = (struct tdb_crypto *) crp->crp_opaque;
  934         IPSEC_ASSERT(tc != NULL, ("esp_output_cb: null opaque data area!"));
  935         m = (struct mbuf *) crp->crp_buf;
  936 
  937         s = splsoftnet();
  938 
  939         isr = tc->tc_isr;
  940         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi, 0, 0);
  941         if (sav == NULL) {
  942                 ESP_STATINC(ESP_STAT_NOTDB);
  943                 DPRINTF(("esp_output_cb: SA expired while in crypto "
  944                     "(SA %s/%08lx proto %u)\n", ipsec_address(&tc->tc_dst),
  945                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  946                 error = ENOBUFS;                /*XXX*/
  947                 goto bad;
  948         }
  949         IPSEC_ASSERT(isr->sav == sav,
  950                 ("esp_output_cb: SA changed was %p now %p\n", isr->sav, sav));
  951 
  952         /* Check for crypto errors. */
  953         if (crp->crp_etype) {
  954                 /* Reset session ID. */
  955                 if (sav->tdb_cryptoid != 0)
  956                         sav->tdb_cryptoid = crp->crp_sid;
  957 
  958                 if (crp->crp_etype == EAGAIN) {
  959                         KEY_FREESAV(&sav);
  960                         splx(s);
  961                         return crypto_dispatch(crp);
  962                 }
  963 
  964                 ESP_STATINC(ESP_STAT_NOXFORM);
  965                 DPRINTF(("esp_output_cb: crypto error %d\n", crp->crp_etype));
  966                 error = crp->crp_etype;
  967                 goto bad;
  968         }
  969 
  970         /* Shouldn't happen... */
  971         if (m == NULL) {
  972                 ESP_STATINC(ESP_STAT_CRYPTO);
  973                 DPRINTF(("esp_output_cb: bogus returned buffer from crypto\n"));
  974                 error = EINVAL;
  975                 goto bad;
  976         }
  977         ESP_STATINC(ESP_STAT_HIST + sav->alg_enc);
  978         if (sav->tdb_authalgxform != NULL)
  979                 AH_STATINC(sav->alg_auth + sav->alg_auth);
  980 
  981         /* Release crypto descriptors. */
  982         free(tc, M_XDATA);
  983         crypto_freereq(crp);
  984 
  985 #ifdef IPSEC_DEBUG
  986         /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
  987         if (ipsec_integrity) {
  988                 static unsigned char ipseczeroes[AH_HMAC_HASHLEN];
  989                 struct auth_hash *esph;
  990 
  991                 /*
  992                  * Corrupt HMAC if we want to test integrity verification of
  993                  * the other side.
  994                  */
  995                 esph = sav->tdb_authalgxform;
  996                 if (esph !=  NULL) {
  997                         m_copyback(m, m->m_pkthdr.len - AH_HMAC_HASHLEN,
  998                             AH_HMAC_HASHLEN, ipseczeroes);
  999                 }
 1000         }
 1001 #endif
 1002 
 1003         /* NB: m is reclaimed by ipsec_process_done. */
 1004         err = ipsec_process_done(m, isr);
 1005         KEY_FREESAV(&sav);
 1006         splx(s);
 1007         return err;
 1008 bad:
 1009         if (sav)
 1010                 KEY_FREESAV(&sav);
 1011         splx(s);
 1012         if (m)
 1013                 m_freem(m);
 1014         free(tc, M_XDATA);
 1015         crypto_freereq(crp);
 1016         return error;
 1017 }
 1018 
 1019 static struct xformsw esp_xformsw = {
 1020         XF_ESP,         XFT_CONF|XFT_AUTH,      "IPsec ESP",
 1021         esp_init,       esp_zeroize,            esp_input,
 1022         esp_output,
 1023         NULL,
 1024 };
 1025 
 1026 INITFN void
 1027 esp_attach(void)
 1028 {
 1029 
 1030         espstat_percpu = percpu_alloc(sizeof(uint64_t) * ESP_NSTATS);
 1031 
 1032 #define MAXIV(xform)                                    \
 1033         if (xform.blocksize > esp_max_ivlen)            \
 1034                 esp_max_ivlen = xform.blocksize         \
 1035 
 1036         esp_max_ivlen = 0;
 1037         MAXIV(enc_xform_des);           /* SADB_EALG_DESCBC */
 1038         MAXIV(enc_xform_3des);          /* SADB_EALG_3DESCBC */
 1039         MAXIV(enc_xform_rijndael128);   /* SADB_X_EALG_AES */
 1040         MAXIV(enc_xform_blf);           /* SADB_X_EALG_BLOWFISHCBC */
 1041         MAXIV(enc_xform_cast5);         /* SADB_X_EALG_CAST128CBC */
 1042         MAXIV(enc_xform_skipjack);      /* SADB_X_EALG_SKIPJACK */
 1043         MAXIV(enc_xform_null);          /* SADB_EALG_NULL */
 1044 
 1045         xform_register(&esp_xformsw);
 1046 #undef MAXIV
 1047 }
 1048 #ifdef __FreeBSD__
 1049 SYSINIT(esp_xform_init, SI_SUB_DRIVERS, SI_ORDER_FIRST, esp_attach, NULL)
 1050 #else
 1051 #endif

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