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 /*      $FreeBSD: stable/8/sys/netipsec/xform_esp.c 221525 2011-05-06 13:24:10Z fabient $       */
    2 /*      $OpenBSD: ip_esp.c,v 1.69 2001/06/26 06:18:59 angelos 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  * The original version of this code was written by John Ioannidis
    9  * for BSD/OS in Athens, Greece, 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 #include "opt_inet.h"
   39 #include "opt_inet6.h"
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/socket.h>
   45 #include <sys/syslog.h>
   46 #include <sys/kernel.h>
   47 #include <sys/random.h>
   48 #include <sys/sysctl.h>
   49 
   50 #include <net/if.h>
   51 #include <net/vnet.h>
   52 
   53 #include <netinet/in.h>
   54 #include <netinet/in_systm.h>
   55 #include <netinet/ip.h>
   56 #include <netinet/ip_ecn.h>
   57 #include <netinet/ip6.h>
   58 
   59 #include <net/route.h>
   60 #include <netipsec/ipsec.h>
   61 #include <netipsec/ah.h>
   62 #include <netipsec/ah_var.h>
   63 #include <netipsec/esp.h>
   64 #include <netipsec/esp_var.h>
   65 #include <netipsec/xform.h>
   66 
   67 #ifdef INET6
   68 #include <netinet6/ip6_var.h>
   69 #include <netipsec/ipsec6.h>
   70 #include <netinet6/ip6_ecn.h>
   71 #endif
   72 
   73 #include <netipsec/key.h>
   74 #include <netipsec/key_debug.h>
   75 
   76 #include <opencrypto/cryptodev.h>
   77 #include <opencrypto/xform.h>
   78 
   79 VNET_DEFINE(int, esp_enable) = 1;
   80 VNET_DEFINE(struct espstat, espstat);
   81 
   82 SYSCTL_DECL(_net_inet_esp);
   83 SYSCTL_VNET_INT(_net_inet_esp, OID_AUTO,
   84         esp_enable,     CTLFLAG_RW,     &VNET_NAME(esp_enable), 0, "");
   85 SYSCTL_VNET_STRUCT(_net_inet_esp, IPSECCTL_STATS,
   86         stats,          CTLFLAG_RD,     &VNET_NAME(espstat),    espstat, "");
   87 
   88 static VNET_DEFINE(int, esp_max_ivlen); /* max iv length over all algorithms */
   89 #define V_esp_max_ivlen VNET(esp_max_ivlen)
   90 
   91 static int esp_input_cb(struct cryptop *op);
   92 static int esp_output_cb(struct cryptop *crp);
   93 
   94 /*
   95  * NB: this is public for use by the PF_KEY support.
   96  * NB: if you add support here; be sure to add code to esp_attach below!
   97  */
   98 struct enc_xform *
   99 esp_algorithm_lookup(int alg)
  100 {
  101         if (alg >= ESP_ALG_MAX)
  102                 return NULL;
  103         switch (alg) {
  104         case SADB_EALG_DESCBC:
  105                 return &enc_xform_des;
  106         case SADB_EALG_3DESCBC:
  107                 return &enc_xform_3des;
  108         case SADB_X_EALG_AES:
  109                 return &enc_xform_rijndael128;
  110         case SADB_X_EALG_BLOWFISHCBC:
  111                 return &enc_xform_blf;
  112         case SADB_X_EALG_CAST128CBC:
  113                 return &enc_xform_cast5;
  114         case SADB_X_EALG_SKIPJACK:
  115                 return &enc_xform_skipjack;
  116         case SADB_EALG_NULL:
  117                 return &enc_xform_null;
  118         case SADB_X_EALG_CAMELLIACBC:
  119                 return &enc_xform_camellia;
  120         }
  121         return NULL;
  122 }
  123 
  124 size_t
  125 esp_hdrsiz(struct secasvar *sav)
  126 {
  127         size_t size;
  128 
  129         if (sav != NULL) {
  130                 /*XXX not right for null algorithm--does it matter??*/
  131                 IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
  132                         ("SA with null xform"));
  133                 if (sav->flags & SADB_X_EXT_OLD)
  134                         size = sizeof (struct esp);
  135                 else
  136                         size = sizeof (struct newesp);
  137                 size += sav->tdb_encalgxform->blocksize + 9;
  138                 /*XXX need alg check???*/
  139                 if (sav->tdb_authalgxform != NULL && sav->replay)
  140                         size += ah_hdrsiz(sav);
  141         } else {
  142                 /*
  143                  *   base header size
  144                  * + max iv length for CBC mode
  145                  * + max pad length
  146                  * + sizeof (pad length field)
  147                  * + sizeof (next header field)
  148                  * + max icv supported.
  149                  */
  150                 size = sizeof (struct newesp) + V_esp_max_ivlen + 9 + 16;
  151         }
  152         return size;
  153 }
  154 
  155 /*
  156  * esp_init() is called when an SPI is being set up.
  157  */
  158 static int
  159 esp_init(struct secasvar *sav, struct xformsw *xsp)
  160 {
  161         struct enc_xform *txform;
  162         struct cryptoini cria, crie;
  163         int keylen;
  164         int error;
  165 
  166         txform = esp_algorithm_lookup(sav->alg_enc);
  167         if (txform == NULL) {
  168                 DPRINTF(("%s: unsupported encryption algorithm %d\n",
  169                         __func__, sav->alg_enc));
  170                 return EINVAL;
  171         }
  172         if (sav->key_enc == NULL) {
  173                 DPRINTF(("%s: no encoding key for %s algorithm\n",
  174                          __func__, txform->name));
  175                 return EINVAL;
  176         }
  177         if ((sav->flags&(SADB_X_EXT_OLD|SADB_X_EXT_IV4B)) == SADB_X_EXT_IV4B) {
  178                 DPRINTF(("%s: 4-byte IV not supported with protocol\n",
  179                         __func__));
  180                 return EINVAL;
  181         }
  182         keylen = _KEYLEN(sav->key_enc);
  183         if (txform->minkey > keylen || keylen > txform->maxkey) {
  184                 DPRINTF(("%s: invalid key length %u, must be in the range "
  185                         "[%u..%u] for algorithm %s\n", __func__,
  186                         keylen, txform->minkey, txform->maxkey,
  187                         txform->name));
  188                 return EINVAL;
  189         }
  190 
  191         /*
  192          * NB: The null xform needs a non-zero blocksize to keep the
  193          *      crypto code happy but if we use it to set ivlen then
  194          *      the ESP header will be processed incorrectly.  The
  195          *      compromise is to force it to zero here.
  196          */
  197         sav->ivlen = (txform == &enc_xform_null ? 0 : txform->blocksize);
  198         sav->iv = (caddr_t) malloc(sav->ivlen, M_XDATA, M_WAITOK);
  199         if (sav->iv == NULL) {
  200                 DPRINTF(("%s: no memory for IV\n", __func__));
  201                 return EINVAL;
  202         }
  203         key_randomfill(sav->iv, sav->ivlen);    /*XXX*/
  204 
  205         /*
  206          * Setup AH-related state.
  207          */
  208         if (sav->alg_auth != 0) {
  209                 error = ah_init0(sav, xsp, &cria);
  210                 if (error)
  211                         return error;
  212         }
  213 
  214         /* NB: override anything set in ah_init0 */
  215         sav->tdb_xform = xsp;
  216         sav->tdb_encalgxform = txform;
  217 
  218         /* Initialize crypto session. */
  219         bzero(&crie, sizeof (crie));
  220         crie.cri_alg = sav->tdb_encalgxform->type;
  221         crie.cri_klen = _KEYBITS(sav->key_enc);
  222         crie.cri_key = sav->key_enc->key_data;
  223         /* XXX Rounds ? */
  224 
  225         if (sav->tdb_authalgxform && sav->tdb_encalgxform) {
  226                 /* init both auth & enc */
  227                 crie.cri_next = &cria;
  228                 error = crypto_newsession(&sav->tdb_cryptoid,
  229                                           &crie, V_crypto_support);
  230         } else if (sav->tdb_encalgxform) {
  231                 error = crypto_newsession(&sav->tdb_cryptoid,
  232                                           &crie, V_crypto_support);
  233         } else if (sav->tdb_authalgxform) {
  234                 error = crypto_newsession(&sav->tdb_cryptoid,
  235                                           &cria, V_crypto_support);
  236         } else {
  237                 /* XXX cannot happen? */
  238                 DPRINTF(("%s: no encoding OR authentication xform!\n",
  239                         __func__));
  240                 error = EINVAL;
  241         }
  242         return error;
  243 }
  244 
  245 /*
  246  * Paranoia.
  247  */
  248 static int
  249 esp_zeroize(struct secasvar *sav)
  250 {
  251         /* NB: ah_zerorize free's the crypto session state */
  252         int error = ah_zeroize(sav);
  253 
  254         if (sav->key_enc)
  255                 bzero(sav->key_enc->key_data, _KEYLEN(sav->key_enc));
  256         if (sav->iv) {
  257                 free(sav->iv, M_XDATA);
  258                 sav->iv = NULL;
  259         }
  260         sav->tdb_encalgxform = NULL;
  261         sav->tdb_xform = NULL;
  262         return error;
  263 }
  264 
  265 /*
  266  * ESP input processing, called (eventually) through the protocol switch.
  267  */
  268 static int
  269 esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
  270 {
  271         struct auth_hash *esph;
  272         struct enc_xform *espx;
  273         struct tdb_ident *tdbi;
  274         struct tdb_crypto *tc;
  275         int plen, alen, hlen;
  276         struct m_tag *mtag;
  277         struct newesp *esp;
  278 
  279         struct cryptodesc *crde;
  280         struct cryptop *crp;
  281 
  282         IPSEC_ASSERT(sav != NULL, ("null SA"));
  283         IPSEC_ASSERT(sav->tdb_encalgxform != NULL, ("null encoding xform"));
  284         IPSEC_ASSERT((skip&3) == 0 && (m->m_pkthdr.len&3) == 0,
  285                 ("misaligned packet, skip %u pkt len %u",
  286                         skip, m->m_pkthdr.len));
  287 
  288         /* XXX don't pullup, just copy header */
  289         IP6_EXTHDR_GET(esp, struct newesp *, m, skip, sizeof (struct newesp));
  290 
  291         esph = sav->tdb_authalgxform;
  292         espx = sav->tdb_encalgxform;
  293 
  294         /* Determine the ESP header length */
  295         if (sav->flags & SADB_X_EXT_OLD)
  296                 hlen = sizeof (struct esp) + sav->ivlen;
  297         else
  298                 hlen = sizeof (struct newesp) + sav->ivlen;
  299         /* Authenticator hash size */
  300         if (esph != NULL) {
  301                 switch (esph->type) {
  302                 case CRYPTO_SHA2_256_HMAC:
  303                 case CRYPTO_SHA2_384_HMAC:
  304                 case CRYPTO_SHA2_512_HMAC:
  305                         alen = esph->hashsize/2;
  306                         break;
  307                 default:
  308                         alen = AH_HMAC_HASHLEN;
  309                         break;
  310                 }
  311         }else
  312                 alen = 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(("%s: payload of %d octets not a multiple of %d octets,"
  325                     "  SA %s/%08lx\n", __func__,
  326                     plen, espx->blocksize,
  327                     ipsec_address(&sav->sah->saidx.dst),
  328                     (u_long) ntohl(sav->spi)));
  329                 V_espstat.esps_badilen++;
  330                 m_freem(m);
  331                 return EINVAL;
  332         }
  333 
  334         /*
  335          * Check sequence number.
  336          */
  337         if (esph && sav->replay && !ipsec_chkreplay(ntohl(esp->esp_seq), sav)) {
  338                 DPRINTF(("%s: packet replay check for %s\n", __func__,
  339                     ipsec_logsastr(sav)));      /*XXX*/
  340                 V_espstat.esps_replay++;
  341                 m_freem(m);
  342                 return ENOBUFS;         /*XXX*/
  343         }
  344 
  345         /* Update the counters */
  346         V_espstat.esps_ibytes += m->m_pkthdr.len - (skip + hlen + alen);
  347 
  348         /* Find out if we've already done crypto */
  349         for (mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, NULL);
  350              mtag != NULL;
  351              mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, mtag)) {
  352                 tdbi = (struct tdb_ident *) (mtag + 1);
  353                 if (tdbi->proto == sav->sah->saidx.proto &&
  354                     tdbi->spi == sav->spi &&
  355                     !bcmp(&tdbi->dst, &sav->sah->saidx.dst,
  356                           sizeof(union sockaddr_union)))
  357                         break;
  358         }
  359 
  360         /* Get crypto descriptors */
  361         crp = crypto_getreq(esph && espx ? 2 : 1);
  362         if (crp == NULL) {
  363                 DPRINTF(("%s: failed to acquire crypto descriptors\n",
  364                         __func__));
  365                 V_espstat.esps_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(("%s: failed to allocate tdb_crypto\n", __func__));
  380                 V_espstat.esps_crypto++;
  381                 m_freem(m);
  382                 return ENOBUFS;
  383         }
  384 
  385         tc->tc_ptr = (caddr_t) mtag;
  386 
  387         if (esph) {
  388                 struct cryptodesc *crda = crp->crp_desc;
  389 
  390                 IPSEC_ASSERT(crda != NULL, ("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 = sav->key_auth->key_data;
  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                                    (caddr_t) (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 | CRYPTO_F_CBIFSYNC;
  415         crp->crp_buf = (caddr_t) m;
  416         crp->crp_callback = esp_input_cb;
  417         crp->crp_sid = sav->tdb_cryptoid;
  418         crp->crp_opaque = (caddr_t) 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         KEY_ADDREFSA(sav);
  427         tc->tc_sav = sav;
  428 
  429         /* Decryption descriptor */
  430         if (espx) {
  431                 IPSEC_ASSERT(crde != NULL, ("null esp crypto descriptor"));
  432                 crde->crd_skip = skip + hlen;
  433                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  434                 crde->crd_inject = skip + hlen - sav->ivlen;
  435 
  436                 crde->crd_alg = espx->type;
  437                 crde->crd_key = sav->key_enc->key_data;
  438                 crde->crd_klen = _KEYBITS(sav->key_enc);
  439                 /* XXX Rounds ? */
  440         }
  441 
  442         if (mtag == NULL)
  443                 return crypto_dispatch(crp);
  444         else
  445                 return esp_input_cb(crp);
  446 }
  447 
  448 #ifdef INET6
  449 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag) do {              \
  450         if (saidx->dst.sa.sa_family == AF_INET6) {                           \
  451                 error = ipsec6_common_input_cb(m, sav, skip, protoff, mtag); \
  452         } else {                                                             \
  453                 error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag); \
  454         }                                                                    \
  455 } while (0)
  456 #else
  457 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag)                   \
  458         (error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag))
  459 #endif
  460 
  461 /*
  462  * ESP input callback from the crypto driver.
  463  */
  464 static int
  465 esp_input_cb(struct cryptop *crp)
  466 {
  467         u_int8_t lastthree[3], aalg[AH_HMAC_MAXHASHLEN];
  468         int hlen, skip, protoff, error, alen;
  469         struct mbuf *m;
  470         struct cryptodesc *crd;
  471         struct auth_hash *esph;
  472         struct enc_xform *espx;
  473         struct tdb_crypto *tc;
  474         struct m_tag *mtag;
  475         struct secasvar *sav;
  476         struct secasindex *saidx;
  477         caddr_t ptr;
  478 
  479         crd = crp->crp_desc;
  480         IPSEC_ASSERT(crd != NULL, ("null crypto descriptor!"));
  481 
  482         tc = (struct tdb_crypto *) crp->crp_opaque;
  483         IPSEC_ASSERT(tc != NULL, ("null opaque crypto data area!"));
  484         skip = tc->tc_skip;
  485         protoff = tc->tc_protoff;
  486         mtag = (struct m_tag *) tc->tc_ptr;
  487         m = (struct mbuf *) crp->crp_buf;
  488 
  489         sav = tc->tc_sav;
  490         IPSEC_ASSERT(sav != NULL, ("null SA!"));
  491 
  492         saidx = &sav->sah->saidx;
  493         IPSEC_ASSERT(saidx->dst.sa.sa_family == AF_INET ||
  494                 saidx->dst.sa.sa_family == AF_INET6,
  495                 ("unexpected protocol family %u", saidx->dst.sa.sa_family));
  496 
  497         esph = sav->tdb_authalgxform;
  498         espx = sav->tdb_encalgxform;
  499 
  500         /* Check for crypto errors */
  501         if (crp->crp_etype) {
  502                 /* Reset the session ID */
  503                 if (sav->tdb_cryptoid != 0)
  504                         sav->tdb_cryptoid = crp->crp_sid;
  505 
  506                 if (crp->crp_etype == EAGAIN) {
  507                         error = crypto_dispatch(crp);
  508                         return error;
  509                 }
  510 
  511                 V_espstat.esps_noxform++;
  512                 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
  513                 error = crp->crp_etype;
  514                 goto bad;
  515         }
  516 
  517         /* Shouldn't happen... */
  518         if (m == NULL) {
  519                 V_espstat.esps_crypto++;
  520                 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
  521                 error = EINVAL;
  522                 goto bad;
  523         }
  524         V_espstat.esps_hist[sav->alg_enc]++;
  525 
  526         /* If authentication was performed, check now. */
  527         if (esph != NULL) {
  528                 switch (esph->type) {
  529                 case CRYPTO_SHA2_256_HMAC:
  530                 case CRYPTO_SHA2_384_HMAC:
  531                 case CRYPTO_SHA2_512_HMAC:
  532                         alen = esph->hashsize/2;
  533                         break;
  534                 default:
  535                         alen = AH_HMAC_HASHLEN;
  536                         break;
  537                 }
  538                 /*
  539                  * If we have a tag, it means an IPsec-aware NIC did
  540                  * the verification for us.  Otherwise we need to
  541                  * check the authentication calculation.
  542                  */
  543                 V_ahstat.ahs_hist[sav->alg_auth]++;
  544                 if (mtag == NULL) {
  545                         /* Copy the authenticator from the packet */
  546                         m_copydata(m, m->m_pkthdr.len - alen,
  547                                 alen, aalg);
  548 
  549                         ptr = (caddr_t) (tc + 1);
  550 
  551                         /* Verify authenticator */
  552                         if (bcmp(ptr, aalg, alen) != 0) {
  553                                 DPRINTF(("%s: "
  554                     "authentication hash mismatch for packet in SA %s/%08lx\n",
  555                                     __func__,
  556                                     ipsec_address(&saidx->dst),
  557                                     (u_long) ntohl(sav->spi)));
  558                                 V_espstat.esps_badauth++;
  559                                 error = EACCES;
  560                                 goto bad;
  561                         }
  562                 }
  563 
  564                 /* Remove trailing authenticator */
  565                 m_adj(m, -alen);
  566         }
  567 
  568         /* Release the crypto descriptors */
  569         free(tc, M_XDATA), tc = NULL;
  570         crypto_freereq(crp), crp = NULL;
  571 
  572         /*
  573          * Packet is now decrypted.
  574          */
  575         m->m_flags |= M_DECRYPTED;
  576 
  577         /*
  578          * Update replay sequence number, if appropriate.
  579          */
  580         if (sav->replay) {
  581                 u_int32_t seq;
  582 
  583                 m_copydata(m, skip + offsetof(struct newesp, esp_seq),
  584                            sizeof (seq), (caddr_t) &seq);
  585                 if (ipsec_updatereplay(ntohl(seq), sav)) {
  586                         DPRINTF(("%s: packet replay check for %s\n", __func__,
  587                             ipsec_logsastr(sav)));
  588                         V_espstat.esps_replay++;
  589                         error = ENOBUFS;
  590                         goto bad;
  591                 }
  592         }
  593 
  594         /* Determine the ESP header length */
  595         if (sav->flags & SADB_X_EXT_OLD)
  596                 hlen = sizeof (struct esp) + sav->ivlen;
  597         else
  598                 hlen = sizeof (struct newesp) + sav->ivlen;
  599 
  600         /* Remove the ESP header and IV from the mbuf. */
  601         error = m_striphdr(m, skip, hlen);
  602         if (error) {
  603                 V_espstat.esps_hdrops++;
  604                 DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__,
  605                     ipsec_address(&sav->sah->saidx.dst),
  606                     (u_long) ntohl(sav->spi)));
  607                 goto bad;
  608         }
  609 
  610         /* Save the last three bytes of decrypted data */
  611         m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);
  612 
  613         /* Verify pad length */
  614         if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
  615                 V_espstat.esps_badilen++;
  616                 DPRINTF(("%s: invalid padding length %d for %u byte packet "
  617                         "in SA %s/%08lx\n", __func__,
  618                          lastthree[1], m->m_pkthdr.len - skip,
  619                          ipsec_address(&sav->sah->saidx.dst),
  620                          (u_long) ntohl(sav->spi)));
  621                 error = EINVAL;
  622                 goto bad;
  623         }
  624 
  625         /* Verify correct decryption by checking the last padding bytes */
  626         if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
  627                 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
  628                         V_espstat.esps_badenc++;
  629                         DPRINTF(("%s: decryption failed for packet in "
  630                                 "SA %s/%08lx\n", __func__,
  631                                 ipsec_address(&sav->sah->saidx.dst),
  632                                 (u_long) ntohl(sav->spi)));
  633                         error = EINVAL;
  634                         goto bad;
  635                 }
  636         }
  637 
  638         /* Trim the mbuf chain to remove trailing authenticator and padding */
  639         m_adj(m, -(lastthree[1] + 2));
  640 
  641         /* Restore the Next Protocol field */
  642         m_copyback(m, protoff, sizeof (u_int8_t), lastthree + 2);
  643 
  644         IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag);
  645 
  646         KEY_FREESAV(&sav);
  647         return error;
  648 bad:
  649         if (sav)
  650                 KEY_FREESAV(&sav);
  651         if (m != NULL)
  652                 m_freem(m);
  653         if (tc != NULL)
  654                 free(tc, M_XDATA);
  655         if (crp != NULL)
  656                 crypto_freereq(crp);
  657         return error;
  658 }
  659 
  660 /*
  661  * ESP output routine, called by ipsec[46]_process_packet().
  662  */
  663 static int
  664 esp_output(
  665         struct mbuf *m,
  666         struct ipsecrequest *isr,
  667         struct mbuf **mp,
  668         int skip,
  669         int protoff
  670 )
  671 {
  672         struct enc_xform *espx;
  673         struct auth_hash *esph;
  674         int hlen, rlen, plen, padding, blks, alen, i, roff;
  675         struct mbuf *mo = (struct mbuf *) NULL;
  676         struct tdb_crypto *tc;
  677         struct secasvar *sav;
  678         struct secasindex *saidx;
  679         unsigned char *pad;
  680         u_int8_t prot;
  681         int error, maxpacketsize;
  682 
  683         struct cryptodesc *crde = NULL, *crda = NULL;
  684         struct cryptop *crp;
  685 
  686         sav = isr->sav;
  687         IPSEC_ASSERT(sav != NULL, ("null SA"));
  688         esph = sav->tdb_authalgxform;
  689         espx = sav->tdb_encalgxform;
  690         IPSEC_ASSERT(espx != NULL, ("null encoding xform"));
  691 
  692         if (sav->flags & SADB_X_EXT_OLD)
  693                 hlen = sizeof (struct esp) + sav->ivlen;
  694         else
  695                 hlen = sizeof (struct newesp) + sav->ivlen;
  696 
  697         rlen = m->m_pkthdr.len - skip;  /* Raw payload length. */
  698         /*
  699          * NB: The null encoding transform has a blocksize of 4
  700          *     so that headers are properly aligned.
  701          */
  702         blks = espx->blocksize;         /* IV blocksize */
  703 
  704         /* XXX clamp padding length a la KAME??? */
  705         padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;
  706         plen = rlen + padding;          /* Padded payload length. */
  707 
  708         if (esph)
  709                 switch (esph->type) {
  710                 case CRYPTO_SHA2_256_HMAC:
  711                 case CRYPTO_SHA2_384_HMAC:
  712                 case CRYPTO_SHA2_512_HMAC:
  713                         alen = esph->hashsize/2;
  714                         break;
  715                 default:
  716                 alen = AH_HMAC_HASHLEN;
  717                         break;
  718                 }
  719         else
  720                 alen = 0;
  721 
  722         V_espstat.esps_output++;
  723 
  724         saidx = &sav->sah->saidx;
  725         /* Check for maximum packet size violations. */
  726         switch (saidx->dst.sa.sa_family) {
  727 #ifdef INET
  728         case AF_INET:
  729                 maxpacketsize = IP_MAXPACKET;
  730                 break;
  731 #endif /* INET */
  732 #ifdef INET6
  733         case AF_INET6:
  734                 maxpacketsize = IPV6_MAXPACKET;
  735                 break;
  736 #endif /* INET6 */
  737         default:
  738                 DPRINTF(("%s: unknown/unsupported protocol "
  739                     "family %d, SA %s/%08lx\n", __func__,
  740                     saidx->dst.sa.sa_family, ipsec_address(&saidx->dst),
  741                     (u_long) ntohl(sav->spi)));
  742                 V_espstat.esps_nopf++;
  743                 error = EPFNOSUPPORT;
  744                 goto bad;
  745         }
  746         if (skip + hlen + rlen + padding + alen > maxpacketsize) {
  747                 DPRINTF(("%s: packet in SA %s/%08lx got too big "
  748                     "(len %u, max len %u)\n", __func__,
  749                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi),
  750                     skip + hlen + rlen + padding + alen, maxpacketsize));
  751                 V_espstat.esps_toobig++;
  752                 error = EMSGSIZE;
  753                 goto bad;
  754         }
  755 
  756         /* Update the counters. */
  757         V_espstat.esps_obytes += m->m_pkthdr.len - skip;
  758 
  759         m = m_unshare(m, M_NOWAIT);
  760         if (m == NULL) {
  761                 DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__,
  762                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  763                 V_espstat.esps_hdrops++;
  764                 error = ENOBUFS;
  765                 goto bad;
  766         }
  767 
  768         /* Inject ESP header. */
  769         mo = m_makespace(m, skip, hlen, &roff);
  770         if (mo == NULL) {
  771                 DPRINTF(("%s: %u byte ESP hdr inject failed for SA %s/%08lx\n",
  772                     __func__, hlen, ipsec_address(&saidx->dst),
  773                     (u_long) ntohl(sav->spi)));
  774                 V_espstat.esps_hdrops++;                /* XXX diffs from openbsd */
  775                 error = ENOBUFS;
  776                 goto bad;
  777         }
  778 
  779         /* Initialize ESP header. */
  780         bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff, sizeof(u_int32_t));
  781         if (sav->replay) {
  782                 u_int32_t replay;
  783 
  784 #ifdef REGRESSION
  785                 /* Emulate replay attack when ipsec_replay is TRUE. */
  786                 if (!V_ipsec_replay)
  787 #endif
  788                         sav->replay->count++;
  789                 replay = htonl(sav->replay->count);
  790                 bcopy((caddr_t) &replay,
  791                     mtod(mo, caddr_t) + roff + sizeof(u_int32_t),
  792                     sizeof(u_int32_t));
  793         }
  794 
  795         /*
  796          * Add padding -- better to do it ourselves than use the crypto engine,
  797          * although if/when we support compression, we'd have to do that.
  798          */
  799         pad = (u_char *) m_pad(m, padding + alen);
  800         if (pad == NULL) {
  801                 DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__,
  802                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  803                 m = NULL;               /* NB: free'd by m_pad */
  804                 error = ENOBUFS;
  805                 goto bad;
  806         }
  807 
  808         /*
  809          * Add padding: random, zero, or self-describing.
  810          * XXX catch unexpected setting
  811          */
  812         switch (sav->flags & SADB_X_EXT_PMASK) {
  813         case SADB_X_EXT_PRAND:
  814                 (void) read_random(pad, padding - 2);
  815                 break;
  816         case SADB_X_EXT_PZERO:
  817                 bzero(pad, padding - 2);
  818                 break;
  819         case SADB_X_EXT_PSEQ:
  820                 for (i = 0; i < padding - 2; i++)
  821                         pad[i] = i+1;
  822                 break;
  823         }
  824 
  825         /* Fix padding length and Next Protocol in padding itself. */
  826         pad[padding - 2] = padding - 2;
  827         m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);
  828 
  829         /* Fix Next Protocol in IPv4/IPv6 header. */
  830         prot = IPPROTO_ESP;
  831         m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);
  832 
  833         /* Get crypto descriptors. */
  834         crp = crypto_getreq(esph && espx ? 2 : 1);
  835         if (crp == NULL) {
  836                 DPRINTF(("%s: failed to acquire crypto descriptors\n",
  837                         __func__));
  838                 V_espstat.esps_crypto++;
  839                 error = ENOBUFS;
  840                 goto bad;
  841         }
  842 
  843         if (espx) {
  844                 crde = crp->crp_desc;
  845                 crda = crde->crd_next;
  846 
  847                 /* Encryption descriptor. */
  848                 crde->crd_skip = skip + hlen;
  849                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  850                 crde->crd_flags = CRD_F_ENCRYPT;
  851                 crde->crd_inject = skip + hlen - sav->ivlen;
  852 
  853                 /* Encryption operation. */
  854                 crde->crd_alg = espx->type;
  855                 crde->crd_key = sav->key_enc->key_data;
  856                 crde->crd_klen = _KEYBITS(sav->key_enc);
  857                 /* XXX Rounds ? */
  858         } else
  859                 crda = crp->crp_desc;
  860 
  861         /* IPsec-specific opaque crypto info. */
  862         tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  863                 M_XDATA, M_NOWAIT|M_ZERO);
  864         if (tc == NULL) {
  865                 crypto_freereq(crp);
  866                 DPRINTF(("%s: failed to allocate tdb_crypto\n", __func__));
  867                 V_espstat.esps_crypto++;
  868                 error = ENOBUFS;
  869                 goto bad;
  870         }
  871 
  872         /* Callback parameters */
  873         tc->tc_isr = isr;
  874         KEY_ADDREFSA(sav);
  875         tc->tc_sav = sav;
  876         tc->tc_spi = sav->spi;
  877         tc->tc_dst = saidx->dst;
  878         tc->tc_proto = saidx->proto;
  879 
  880         /* Crypto operation descriptor. */
  881         crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
  882         crp->crp_flags = CRYPTO_F_IMBUF | CRYPTO_F_CBIFSYNC;
  883         crp->crp_buf = (caddr_t) m;
  884         crp->crp_callback = esp_output_cb;
  885         crp->crp_opaque = (caddr_t) tc;
  886         crp->crp_sid = sav->tdb_cryptoid;
  887 
  888         if (esph) {
  889                 /* Authentication descriptor. */
  890                 crda->crd_skip = skip;
  891                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  892                 crda->crd_inject = m->m_pkthdr.len - alen;
  893 
  894                 /* Authentication operation. */
  895                 crda->crd_alg = esph->type;
  896                 crda->crd_key = sav->key_auth->key_data;
  897                 crda->crd_klen = _KEYBITS(sav->key_auth);
  898         }
  899 
  900         return crypto_dispatch(crp);
  901 bad:
  902         if (m)
  903                 m_freem(m);
  904         return (error);
  905 }
  906 
  907 /*
  908  * ESP output callback from the crypto driver.
  909  */
  910 static int
  911 esp_output_cb(struct cryptop *crp)
  912 {
  913         struct tdb_crypto *tc;
  914         struct ipsecrequest *isr;
  915         struct secasvar *sav;
  916         struct mbuf *m;
  917         int err, error;
  918 
  919         tc = (struct tdb_crypto *) crp->crp_opaque;
  920         IPSEC_ASSERT(tc != NULL, ("null opaque data area!"));
  921         m = (struct mbuf *) crp->crp_buf;
  922 
  923         isr = tc->tc_isr;
  924         IPSECREQUEST_LOCK(isr);
  925         sav = tc->tc_sav;
  926         /* With the isr lock released SA pointer can be updated. */
  927         if (sav != isr->sav) {
  928                 V_espstat.esps_notdb++;
  929                 DPRINTF(("%s: SA gone during crypto (SA %s/%08lx proto %u)\n",
  930                     __func__, ipsec_address(&tc->tc_dst),
  931                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  932                 error = ENOBUFS;                /*XXX*/
  933                 goto bad;
  934         }
  935 
  936         /* Check for crypto errors. */
  937         if (crp->crp_etype) {
  938                 /* Reset session ID. */
  939                 if (sav->tdb_cryptoid != 0)
  940                         sav->tdb_cryptoid = crp->crp_sid;
  941 
  942                 if (crp->crp_etype == EAGAIN) {
  943                         IPSECREQUEST_UNLOCK(isr);
  944                         error = crypto_dispatch(crp);
  945                         return error;
  946                 }
  947 
  948                 V_espstat.esps_noxform++;
  949                 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
  950                 error = crp->crp_etype;
  951                 goto bad;
  952         }
  953 
  954         /* Shouldn't happen... */
  955         if (m == NULL) {
  956                 V_espstat.esps_crypto++;
  957                 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
  958                 error = EINVAL;
  959                 goto bad;
  960         }
  961         V_espstat.esps_hist[sav->alg_enc]++;
  962         if (sav->tdb_authalgxform != NULL)
  963                 V_ahstat.ahs_hist[sav->alg_auth]++;
  964 
  965         /* Release crypto descriptors. */
  966         free(tc, M_XDATA);
  967         crypto_freereq(crp);
  968 
  969 #ifdef REGRESSION
  970         /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
  971         if (V_ipsec_integrity) {
  972                 static unsigned char ipseczeroes[AH_HMAC_MAXHASHLEN];
  973                 struct auth_hash *esph;
  974 
  975                 /*
  976                  * Corrupt HMAC if we want to test integrity verification of
  977                  * the other side.
  978                  */
  979                 esph = sav->tdb_authalgxform;
  980                 if (esph !=  NULL) {
  981                         int alen;
  982 
  983                         switch (esph->type) {
  984                         case CRYPTO_SHA2_256_HMAC:
  985                         case CRYPTO_SHA2_384_HMAC:
  986                         case CRYPTO_SHA2_512_HMAC:
  987                                 alen = esph->hashsize/2;
  988                                 break;
  989                         default:
  990                                 alen = AH_HMAC_HASHLEN;
  991                                 break;
  992                         }
  993                         m_copyback(m, m->m_pkthdr.len - alen,
  994                             alen, ipseczeroes);
  995                 }
  996         }
  997 #endif
  998 
  999         /* NB: m is reclaimed by ipsec_process_done. */
 1000         err = ipsec_process_done(m, isr);
 1001         KEY_FREESAV(&sav);
 1002         IPSECREQUEST_UNLOCK(isr);
 1003         return err;
 1004 bad:
 1005         if (sav)
 1006                 KEY_FREESAV(&sav);
 1007         IPSECREQUEST_UNLOCK(isr);
 1008         if (m)
 1009                 m_freem(m);
 1010         free(tc, M_XDATA);
 1011         crypto_freereq(crp);
 1012         return error;
 1013 }
 1014 
 1015 static struct xformsw esp_xformsw = {
 1016         XF_ESP,         XFT_CONF|XFT_AUTH,      "IPsec ESP",
 1017         esp_init,       esp_zeroize,            esp_input,
 1018         esp_output
 1019 };
 1020 
 1021 static void
 1022 esp_attach(void)
 1023 {
 1024 #define MAXIV(xform)                                    \
 1025         if (xform.blocksize > V_esp_max_ivlen)          \
 1026                 V_esp_max_ivlen = xform.blocksize       \
 1027 
 1028         MAXIV(enc_xform_des);           /* SADB_EALG_DESCBC */
 1029         MAXIV(enc_xform_3des);          /* SADB_EALG_3DESCBC */
 1030         MAXIV(enc_xform_rijndael128);   /* SADB_X_EALG_AES */
 1031         MAXIV(enc_xform_blf);           /* SADB_X_EALG_BLOWFISHCBC */
 1032         MAXIV(enc_xform_cast5);         /* SADB_X_EALG_CAST128CBC */
 1033         MAXIV(enc_xform_skipjack);      /* SADB_X_EALG_SKIPJACK */
 1034         MAXIV(enc_xform_null);          /* SADB_EALG_NULL */
 1035         MAXIV(enc_xform_camellia);      /* SADB_X_EALG_CAMELLIACBC */
 1036 
 1037         xform_register(&esp_xformsw);
 1038 #undef MAXIV
 1039 }
 1040 SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, esp_attach, NULL);

Cache object: f6846757370dd0e9e56b3c0c7fcf75c5


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