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: releng/8.1/sys/netipsec/xform_esp.c 207695 2010-05-06 06:44:19Z bz $  */
    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         alen = esph ? AH_HMAC_HASHLEN : 0;
  301 
  302         /*
  303          * Verify payload length is multiple of encryption algorithm
  304          * block size.
  305          *
  306          * NB: This works for the null algorithm because the blocksize
  307          *     is 4 and all packets must be 4-byte aligned regardless
  308          *     of the algorithm.
  309          */
  310         plen = m->m_pkthdr.len - (skip + hlen + alen);
  311         if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
  312                 DPRINTF(("%s: payload of %d octets not a multiple of %d octets,"
  313                     "  SA %s/%08lx\n", __func__,
  314                     plen, espx->blocksize,
  315                     ipsec_address(&sav->sah->saidx.dst),
  316                     (u_long) ntohl(sav->spi)));
  317                 V_espstat.esps_badilen++;
  318                 m_freem(m);
  319                 return EINVAL;
  320         }
  321 
  322         /*
  323          * Check sequence number.
  324          */
  325         if (esph && sav->replay && !ipsec_chkreplay(ntohl(esp->esp_seq), sav)) {
  326                 DPRINTF(("%s: packet replay check for %s\n", __func__,
  327                     ipsec_logsastr(sav)));      /*XXX*/
  328                 V_espstat.esps_replay++;
  329                 m_freem(m);
  330                 return ENOBUFS;         /*XXX*/
  331         }
  332 
  333         /* Update the counters */
  334         V_espstat.esps_ibytes += m->m_pkthdr.len - (skip + hlen + alen);
  335 
  336         /* Find out if we've already done crypto */
  337         for (mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, NULL);
  338              mtag != NULL;
  339              mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, mtag)) {
  340                 tdbi = (struct tdb_ident *) (mtag + 1);
  341                 if (tdbi->proto == sav->sah->saidx.proto &&
  342                     tdbi->spi == sav->spi &&
  343                     !bcmp(&tdbi->dst, &sav->sah->saidx.dst,
  344                           sizeof(union sockaddr_union)))
  345                         break;
  346         }
  347 
  348         /* Get crypto descriptors */
  349         crp = crypto_getreq(esph && espx ? 2 : 1);
  350         if (crp == NULL) {
  351                 DPRINTF(("%s: failed to acquire crypto descriptors\n",
  352                         __func__));
  353                 V_espstat.esps_crypto++;
  354                 m_freem(m);
  355                 return ENOBUFS;
  356         }
  357 
  358         /* Get IPsec-specific opaque pointer */
  359         if (esph == NULL || mtag != NULL)
  360                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  361                     M_XDATA, M_NOWAIT|M_ZERO);
  362         else
  363                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto) + alen,
  364                     M_XDATA, M_NOWAIT|M_ZERO);
  365         if (tc == NULL) {
  366                 crypto_freereq(crp);
  367                 DPRINTF(("%s: failed to allocate tdb_crypto\n", __func__));
  368                 V_espstat.esps_crypto++;
  369                 m_freem(m);
  370                 return ENOBUFS;
  371         }
  372 
  373         tc->tc_ptr = (caddr_t) mtag;
  374 
  375         if (esph) {
  376                 struct cryptodesc *crda = crp->crp_desc;
  377 
  378                 IPSEC_ASSERT(crda != NULL, ("null ah crypto descriptor"));
  379 
  380                 /* Authentication descriptor */
  381                 crda->crd_skip = skip;
  382                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  383                 crda->crd_inject = m->m_pkthdr.len - alen;
  384 
  385                 crda->crd_alg = esph->type;
  386                 crda->crd_key = sav->key_auth->key_data;
  387                 crda->crd_klen = _KEYBITS(sav->key_auth);
  388 
  389                 /* Copy the authenticator */
  390                 if (mtag == NULL)
  391                         m_copydata(m, m->m_pkthdr.len - alen, alen,
  392                                    (caddr_t) (tc + 1));
  393 
  394                 /* Chain authentication request */
  395                 crde = crda->crd_next;
  396         } else {
  397                 crde = crp->crp_desc;
  398         }
  399 
  400         /* Crypto operation descriptor */
  401         crp->crp_ilen = m->m_pkthdr.len; /* Total input length */
  402         crp->crp_flags = CRYPTO_F_IMBUF | CRYPTO_F_CBIFSYNC;
  403         crp->crp_buf = (caddr_t) m;
  404         crp->crp_callback = esp_input_cb;
  405         crp->crp_sid = sav->tdb_cryptoid;
  406         crp->crp_opaque = (caddr_t) tc;
  407 
  408         /* These are passed as-is to the callback */
  409         tc->tc_spi = sav->spi;
  410         tc->tc_dst = sav->sah->saidx.dst;
  411         tc->tc_proto = sav->sah->saidx.proto;
  412         tc->tc_protoff = protoff;
  413         tc->tc_skip = skip;
  414 
  415         /* Decryption descriptor */
  416         if (espx) {
  417                 IPSEC_ASSERT(crde != NULL, ("null esp crypto descriptor"));
  418                 crde->crd_skip = skip + hlen;
  419                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  420                 crde->crd_inject = skip + hlen - sav->ivlen;
  421 
  422                 crde->crd_alg = espx->type;
  423                 crde->crd_key = sav->key_enc->key_data;
  424                 crde->crd_klen = _KEYBITS(sav->key_enc);
  425                 /* XXX Rounds ? */
  426         }
  427 
  428         if (mtag == NULL)
  429                 return crypto_dispatch(crp);
  430         else
  431                 return esp_input_cb(crp);
  432 }
  433 
  434 #ifdef INET6
  435 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag) do {              \
  436         if (saidx->dst.sa.sa_family == AF_INET6) {                           \
  437                 error = ipsec6_common_input_cb(m, sav, skip, protoff, mtag); \
  438         } else {                                                             \
  439                 error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag); \
  440         }                                                                    \
  441 } while (0)
  442 #else
  443 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag)                   \
  444         (error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag))
  445 #endif
  446 
  447 /*
  448  * ESP input callback from the crypto driver.
  449  */
  450 static int
  451 esp_input_cb(struct cryptop *crp)
  452 {
  453         u_int8_t lastthree[3], aalg[AH_HMAC_HASHLEN];
  454         int hlen, skip, protoff, error;
  455         struct mbuf *m;
  456         struct cryptodesc *crd;
  457         struct auth_hash *esph;
  458         struct enc_xform *espx;
  459         struct tdb_crypto *tc;
  460         struct m_tag *mtag;
  461         struct secasvar *sav;
  462         struct secasindex *saidx;
  463         caddr_t ptr;
  464 
  465         crd = crp->crp_desc;
  466         IPSEC_ASSERT(crd != NULL, ("null crypto descriptor!"));
  467 
  468         tc = (struct tdb_crypto *) crp->crp_opaque;
  469         IPSEC_ASSERT(tc != NULL, ("null opaque crypto data area!"));
  470         skip = tc->tc_skip;
  471         protoff = tc->tc_protoff;
  472         mtag = (struct m_tag *) tc->tc_ptr;
  473         m = (struct mbuf *) crp->crp_buf;
  474 
  475         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi);
  476         if (sav == NULL) {
  477                 V_espstat.esps_notdb++;
  478                 DPRINTF(("%s: SA gone during crypto (SA %s/%08lx proto %u)\n",
  479                     __func__, ipsec_address(&tc->tc_dst),
  480                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  481                 error = ENOBUFS;                /*XXX*/
  482                 goto bad;
  483         }
  484 
  485         saidx = &sav->sah->saidx;
  486         IPSEC_ASSERT(saidx->dst.sa.sa_family == AF_INET ||
  487                 saidx->dst.sa.sa_family == AF_INET6,
  488                 ("unexpected protocol family %u", saidx->dst.sa.sa_family));
  489 
  490         esph = sav->tdb_authalgxform;
  491         espx = sav->tdb_encalgxform;
  492 
  493         /* Check for crypto errors */
  494         if (crp->crp_etype) {
  495                 /* Reset the session ID */
  496                 if (sav->tdb_cryptoid != 0)
  497                         sav->tdb_cryptoid = crp->crp_sid;
  498 
  499                 if (crp->crp_etype == EAGAIN) {
  500                         KEY_FREESAV(&sav);
  501                         error = crypto_dispatch(crp);
  502                         return error;
  503                 }
  504 
  505                 V_espstat.esps_noxform++;
  506                 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
  507                 error = crp->crp_etype;
  508                 goto bad;
  509         }
  510 
  511         /* Shouldn't happen... */
  512         if (m == NULL) {
  513                 V_espstat.esps_crypto++;
  514                 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
  515                 error = EINVAL;
  516                 goto bad;
  517         }
  518         V_espstat.esps_hist[sav->alg_enc]++;
  519 
  520         /* If authentication was performed, check now. */
  521         if (esph != NULL) {
  522                 /*
  523                  * If we have a tag, it means an IPsec-aware NIC did
  524                  * the verification for us.  Otherwise we need to
  525                  * check the authentication calculation.
  526                  */
  527                 V_ahstat.ahs_hist[sav->alg_auth]++;
  528                 if (mtag == NULL) {
  529                         /* Copy the authenticator from the packet */
  530                         m_copydata(m, m->m_pkthdr.len - AH_HMAC_HASHLEN,
  531                                 AH_HMAC_HASHLEN, aalg);
  532 
  533                         ptr = (caddr_t) (tc + 1);
  534 
  535                         /* Verify authenticator */
  536                         if (bcmp(ptr, aalg, AH_HMAC_HASHLEN) != 0) {
  537                                 DPRINTF(("%s: "
  538                     "authentication hash mismatch for packet in SA %s/%08lx\n",
  539                                     __func__,
  540                                     ipsec_address(&saidx->dst),
  541                                     (u_long) ntohl(sav->spi)));
  542                                 V_espstat.esps_badauth++;
  543                                 error = EACCES;
  544                                 goto bad;
  545                         }
  546                 }
  547 
  548                 /* Remove trailing authenticator */
  549                 m_adj(m, -AH_HMAC_HASHLEN);
  550         }
  551 
  552         /* Release the crypto descriptors */
  553         free(tc, M_XDATA), tc = NULL;
  554         crypto_freereq(crp), crp = NULL;
  555 
  556         /*
  557          * Packet is now decrypted.
  558          */
  559         m->m_flags |= M_DECRYPTED;
  560 
  561         /*
  562          * Update replay sequence number, if appropriate.
  563          */
  564         if (sav->replay) {
  565                 u_int32_t seq;
  566 
  567                 m_copydata(m, skip + offsetof(struct newesp, esp_seq),
  568                            sizeof (seq), (caddr_t) &seq);
  569                 if (ipsec_updatereplay(ntohl(seq), sav)) {
  570                         DPRINTF(("%s: packet replay check for %s\n", __func__,
  571                             ipsec_logsastr(sav)));
  572                         V_espstat.esps_replay++;
  573                         error = ENOBUFS;
  574                         goto bad;
  575                 }
  576         }
  577 
  578         /* Determine the ESP header length */
  579         if (sav->flags & SADB_X_EXT_OLD)
  580                 hlen = sizeof (struct esp) + sav->ivlen;
  581         else
  582                 hlen = sizeof (struct newesp) + sav->ivlen;
  583 
  584         /* Remove the ESP header and IV from the mbuf. */
  585         error = m_striphdr(m, skip, hlen);
  586         if (error) {
  587                 V_espstat.esps_hdrops++;
  588                 DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__,
  589                     ipsec_address(&sav->sah->saidx.dst),
  590                     (u_long) ntohl(sav->spi)));
  591                 goto bad;
  592         }
  593 
  594         /* Save the last three bytes of decrypted data */
  595         m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);
  596 
  597         /* Verify pad length */
  598         if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
  599                 V_espstat.esps_badilen++;
  600                 DPRINTF(("%s: invalid padding length %d for %u byte packet "
  601                         "in SA %s/%08lx\n", __func__,
  602                          lastthree[1], m->m_pkthdr.len - skip,
  603                          ipsec_address(&sav->sah->saidx.dst),
  604                          (u_long) ntohl(sav->spi)));
  605                 error = EINVAL;
  606                 goto bad;
  607         }
  608 
  609         /* Verify correct decryption by checking the last padding bytes */
  610         if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
  611                 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
  612                         V_espstat.esps_badenc++;
  613                         DPRINTF(("%s: decryption failed for packet in "
  614                                 "SA %s/%08lx\n", __func__,
  615                                 ipsec_address(&sav->sah->saidx.dst),
  616                                 (u_long) ntohl(sav->spi)));
  617                         error = EINVAL;
  618                         goto bad;
  619                 }
  620         }
  621 
  622         /* Trim the mbuf chain to remove trailing authenticator and padding */
  623         m_adj(m, -(lastthree[1] + 2));
  624 
  625         /* Restore the Next Protocol field */
  626         m_copyback(m, protoff, sizeof (u_int8_t), lastthree + 2);
  627 
  628         IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag);
  629 
  630         KEY_FREESAV(&sav);
  631         return error;
  632 bad:
  633         if (sav)
  634                 KEY_FREESAV(&sav);
  635         if (m != NULL)
  636                 m_freem(m);
  637         if (tc != NULL)
  638                 free(tc, M_XDATA);
  639         if (crp != NULL)
  640                 crypto_freereq(crp);
  641         return error;
  642 }
  643 
  644 /*
  645  * ESP output routine, called by ipsec[46]_process_packet().
  646  */
  647 static int
  648 esp_output(
  649         struct mbuf *m,
  650         struct ipsecrequest *isr,
  651         struct mbuf **mp,
  652         int skip,
  653         int protoff
  654 )
  655 {
  656         struct enc_xform *espx;
  657         struct auth_hash *esph;
  658         int hlen, rlen, plen, padding, blks, alen, i, roff;
  659         struct mbuf *mo = (struct mbuf *) NULL;
  660         struct tdb_crypto *tc;
  661         struct secasvar *sav;
  662         struct secasindex *saidx;
  663         unsigned char *pad;
  664         u_int8_t prot;
  665         int error, maxpacketsize;
  666 
  667         struct cryptodesc *crde = NULL, *crda = NULL;
  668         struct cryptop *crp;
  669 
  670         sav = isr->sav;
  671         IPSEC_ASSERT(sav != NULL, ("null SA"));
  672         esph = sav->tdb_authalgxform;
  673         espx = sav->tdb_encalgxform;
  674         IPSEC_ASSERT(espx != NULL, ("null encoding xform"));
  675 
  676         if (sav->flags & SADB_X_EXT_OLD)
  677                 hlen = sizeof (struct esp) + sav->ivlen;
  678         else
  679                 hlen = sizeof (struct newesp) + sav->ivlen;
  680 
  681         rlen = m->m_pkthdr.len - skip;  /* Raw payload length. */
  682         /*
  683          * NB: The null encoding transform has a blocksize of 4
  684          *     so that headers are properly aligned.
  685          */
  686         blks = espx->blocksize;         /* IV blocksize */
  687 
  688         /* XXX clamp padding length a la KAME??? */
  689         padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;
  690         plen = rlen + padding;          /* Padded payload length. */
  691 
  692         if (esph)
  693                 alen = AH_HMAC_HASHLEN;
  694         else
  695                 alen = 0;
  696 
  697         V_espstat.esps_output++;
  698 
  699         saidx = &sav->sah->saidx;
  700         /* Check for maximum packet size violations. */
  701         switch (saidx->dst.sa.sa_family) {
  702 #ifdef INET
  703         case AF_INET:
  704                 maxpacketsize = IP_MAXPACKET;
  705                 break;
  706 #endif /* INET */
  707 #ifdef INET6
  708         case AF_INET6:
  709                 maxpacketsize = IPV6_MAXPACKET;
  710                 break;
  711 #endif /* INET6 */
  712         default:
  713                 DPRINTF(("%s: unknown/unsupported protocol "
  714                     "family %d, SA %s/%08lx\n", __func__,
  715                     saidx->dst.sa.sa_family, ipsec_address(&saidx->dst),
  716                     (u_long) ntohl(sav->spi)));
  717                 V_espstat.esps_nopf++;
  718                 error = EPFNOSUPPORT;
  719                 goto bad;
  720         }
  721         if (skip + hlen + rlen + padding + alen > maxpacketsize) {
  722                 DPRINTF(("%s: packet in SA %s/%08lx got too big "
  723                     "(len %u, max len %u)\n", __func__,
  724                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi),
  725                     skip + hlen + rlen + padding + alen, maxpacketsize));
  726                 V_espstat.esps_toobig++;
  727                 error = EMSGSIZE;
  728                 goto bad;
  729         }
  730 
  731         /* Update the counters. */
  732         V_espstat.esps_obytes += m->m_pkthdr.len - skip;
  733 
  734         m = m_unshare(m, M_NOWAIT);
  735         if (m == NULL) {
  736                 DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__,
  737                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  738                 V_espstat.esps_hdrops++;
  739                 error = ENOBUFS;
  740                 goto bad;
  741         }
  742 
  743         /* Inject ESP header. */
  744         mo = m_makespace(m, skip, hlen, &roff);
  745         if (mo == NULL) {
  746                 DPRINTF(("%s: %u byte ESP hdr inject failed for SA %s/%08lx\n",
  747                     __func__, hlen, ipsec_address(&saidx->dst),
  748                     (u_long) ntohl(sav->spi)));
  749                 V_espstat.esps_hdrops++;                /* XXX diffs from openbsd */
  750                 error = ENOBUFS;
  751                 goto bad;
  752         }
  753 
  754         /* Initialize ESP header. */
  755         bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff, sizeof(u_int32_t));
  756         if (sav->replay) {
  757                 u_int32_t replay;
  758 
  759 #ifdef REGRESSION
  760                 /* Emulate replay attack when ipsec_replay is TRUE. */
  761                 if (!V_ipsec_replay)
  762 #endif
  763                         sav->replay->count++;
  764                 replay = htonl(sav->replay->count);
  765                 bcopy((caddr_t) &replay,
  766                     mtod(mo, caddr_t) + roff + sizeof(u_int32_t),
  767                     sizeof(u_int32_t));
  768         }
  769 
  770         /*
  771          * Add padding -- better to do it ourselves than use the crypto engine,
  772          * although if/when we support compression, we'd have to do that.
  773          */
  774         pad = (u_char *) m_pad(m, padding + alen);
  775         if (pad == NULL) {
  776                 DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__,
  777                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  778                 m = NULL;               /* NB: free'd by m_pad */
  779                 error = ENOBUFS;
  780                 goto bad;
  781         }
  782 
  783         /*
  784          * Add padding: random, zero, or self-describing.
  785          * XXX catch unexpected setting
  786          */
  787         switch (sav->flags & SADB_X_EXT_PMASK) {
  788         case SADB_X_EXT_PRAND:
  789                 (void) read_random(pad, padding - 2);
  790                 break;
  791         case SADB_X_EXT_PZERO:
  792                 bzero(pad, padding - 2);
  793                 break;
  794         case SADB_X_EXT_PSEQ:
  795                 for (i = 0; i < padding - 2; i++)
  796                         pad[i] = i+1;
  797                 break;
  798         }
  799 
  800         /* Fix padding length and Next Protocol in padding itself. */
  801         pad[padding - 2] = padding - 2;
  802         m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);
  803 
  804         /* Fix Next Protocol in IPv4/IPv6 header. */
  805         prot = IPPROTO_ESP;
  806         m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);
  807 
  808         /* Get crypto descriptors. */
  809         crp = crypto_getreq(esph && espx ? 2 : 1);
  810         if (crp == NULL) {
  811                 DPRINTF(("%s: failed to acquire crypto descriptors\n",
  812                         __func__));
  813                 V_espstat.esps_crypto++;
  814                 error = ENOBUFS;
  815                 goto bad;
  816         }
  817 
  818         if (espx) {
  819                 crde = crp->crp_desc;
  820                 crda = crde->crd_next;
  821 
  822                 /* Encryption descriptor. */
  823                 crde->crd_skip = skip + hlen;
  824                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  825                 crde->crd_flags = CRD_F_ENCRYPT;
  826                 crde->crd_inject = skip + hlen - sav->ivlen;
  827 
  828                 /* Encryption operation. */
  829                 crde->crd_alg = espx->type;
  830                 crde->crd_key = sav->key_enc->key_data;
  831                 crde->crd_klen = _KEYBITS(sav->key_enc);
  832                 /* XXX Rounds ? */
  833         } else
  834                 crda = crp->crp_desc;
  835 
  836         /* IPsec-specific opaque crypto info. */
  837         tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  838                 M_XDATA, M_NOWAIT|M_ZERO);
  839         if (tc == NULL) {
  840                 crypto_freereq(crp);
  841                 DPRINTF(("%s: failed to allocate tdb_crypto\n", __func__));
  842                 V_espstat.esps_crypto++;
  843                 error = ENOBUFS;
  844                 goto bad;
  845         }
  846 
  847         /* Callback parameters */
  848         tc->tc_isr = isr;
  849         tc->tc_spi = sav->spi;
  850         tc->tc_dst = saidx->dst;
  851         tc->tc_proto = saidx->proto;
  852 
  853         /* Crypto operation descriptor. */
  854         crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
  855         crp->crp_flags = CRYPTO_F_IMBUF | CRYPTO_F_CBIFSYNC;
  856         crp->crp_buf = (caddr_t) m;
  857         crp->crp_callback = esp_output_cb;
  858         crp->crp_opaque = (caddr_t) tc;
  859         crp->crp_sid = sav->tdb_cryptoid;
  860 
  861         if (esph) {
  862                 /* Authentication descriptor. */
  863                 crda->crd_skip = skip;
  864                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  865                 crda->crd_inject = m->m_pkthdr.len - alen;
  866 
  867                 /* Authentication operation. */
  868                 crda->crd_alg = esph->type;
  869                 crda->crd_key = sav->key_auth->key_data;
  870                 crda->crd_klen = _KEYBITS(sav->key_auth);
  871         }
  872 
  873         return crypto_dispatch(crp);
  874 bad:
  875         if (m)
  876                 m_freem(m);
  877         return (error);
  878 }
  879 
  880 /*
  881  * ESP output callback from the crypto driver.
  882  */
  883 static int
  884 esp_output_cb(struct cryptop *crp)
  885 {
  886         struct tdb_crypto *tc;
  887         struct ipsecrequest *isr;
  888         struct secasvar *sav;
  889         struct mbuf *m;
  890         int err, error;
  891 
  892         tc = (struct tdb_crypto *) crp->crp_opaque;
  893         IPSEC_ASSERT(tc != NULL, ("null opaque data area!"));
  894         m = (struct mbuf *) crp->crp_buf;
  895 
  896         isr = tc->tc_isr;
  897         IPSECREQUEST_LOCK(isr);
  898         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi);
  899         if (sav == NULL) {
  900                 V_espstat.esps_notdb++;
  901                 DPRINTF(("%s: SA gone during crypto (SA %s/%08lx proto %u)\n",
  902                     __func__, ipsec_address(&tc->tc_dst),
  903                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  904                 error = ENOBUFS;                /*XXX*/
  905                 goto bad;
  906         }
  907         IPSEC_ASSERT(isr->sav == sav,
  908                 ("SA changed was %p now %p\n", isr->sav, sav));
  909 
  910         /* Check for crypto errors. */
  911         if (crp->crp_etype) {
  912                 /* Reset session ID. */
  913                 if (sav->tdb_cryptoid != 0)
  914                         sav->tdb_cryptoid = crp->crp_sid;
  915 
  916                 if (crp->crp_etype == EAGAIN) {
  917                         KEY_FREESAV(&sav);
  918                         IPSECREQUEST_UNLOCK(isr);
  919                         error = crypto_dispatch(crp);
  920                         return error;
  921                 }
  922 
  923                 V_espstat.esps_noxform++;
  924                 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
  925                 error = crp->crp_etype;
  926                 goto bad;
  927         }
  928 
  929         /* Shouldn't happen... */
  930         if (m == NULL) {
  931                 V_espstat.esps_crypto++;
  932                 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
  933                 error = EINVAL;
  934                 goto bad;
  935         }
  936         V_espstat.esps_hist[sav->alg_enc]++;
  937         if (sav->tdb_authalgxform != NULL)
  938                 V_ahstat.ahs_hist[sav->alg_auth]++;
  939 
  940         /* Release crypto descriptors. */
  941         free(tc, M_XDATA);
  942         crypto_freereq(crp);
  943 
  944 #ifdef REGRESSION
  945         /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
  946         if (V_ipsec_integrity) {
  947                 static unsigned char ipseczeroes[AH_HMAC_HASHLEN];
  948                 struct auth_hash *esph;
  949 
  950                 /*
  951                  * Corrupt HMAC if we want to test integrity verification of
  952                  * the other side.
  953                  */
  954                 esph = sav->tdb_authalgxform;
  955                 if (esph !=  NULL) {
  956                         m_copyback(m, m->m_pkthdr.len - AH_HMAC_HASHLEN,
  957                             AH_HMAC_HASHLEN, ipseczeroes);
  958                 }
  959         }
  960 #endif
  961 
  962         /* NB: m is reclaimed by ipsec_process_done. */
  963         err = ipsec_process_done(m, isr);
  964         KEY_FREESAV(&sav);
  965         IPSECREQUEST_UNLOCK(isr);
  966         return err;
  967 bad:
  968         if (sav)
  969                 KEY_FREESAV(&sav);
  970         IPSECREQUEST_UNLOCK(isr);
  971         if (m)
  972                 m_freem(m);
  973         free(tc, M_XDATA);
  974         crypto_freereq(crp);
  975         return error;
  976 }
  977 
  978 static struct xformsw esp_xformsw = {
  979         XF_ESP,         XFT_CONF|XFT_AUTH,      "IPsec ESP",
  980         esp_init,       esp_zeroize,            esp_input,
  981         esp_output
  982 };
  983 
  984 static void
  985 esp_attach(void)
  986 {
  987 #define MAXIV(xform)                                    \
  988         if (xform.blocksize > V_esp_max_ivlen)          \
  989                 V_esp_max_ivlen = xform.blocksize       \
  990 
  991         MAXIV(enc_xform_des);           /* SADB_EALG_DESCBC */
  992         MAXIV(enc_xform_3des);          /* SADB_EALG_3DESCBC */
  993         MAXIV(enc_xform_rijndael128);   /* SADB_X_EALG_AES */
  994         MAXIV(enc_xform_blf);           /* SADB_X_EALG_BLOWFISHCBC */
  995         MAXIV(enc_xform_cast5);         /* SADB_X_EALG_CAST128CBC */
  996         MAXIV(enc_xform_skipjack);      /* SADB_X_EALG_SKIPJACK */
  997         MAXIV(enc_xform_null);          /* SADB_EALG_NULL */
  998         MAXIV(enc_xform_camellia);      /* SADB_X_EALG_CAMELLIACBC */
  999 
 1000         xform_register(&esp_xformsw);
 1001 #undef MAXIV
 1002 }
 1003 SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, esp_attach, NULL);

Cache object: e0e208c5423cff6df1da18aecf58aba7


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