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/8.0/sys/netipsec/xform_esp.c 196019 2009-08-01 19:26:27Z rwatson $     */
    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 /* max iv length over all algorithms */
   89 static VNET_DEFINE(int, esp_max_ivlen) = 0;
   90 #define V_esp_max_ivlen VNET(esp_max_ivlen)
   91 
   92 static int esp_input_cb(struct cryptop *op);
   93 static int esp_output_cb(struct cryptop *crp);
   94 
   95 /*
   96  * NB: this is public for use by the PF_KEY support.
   97  * NB: if you add support here; be sure to add code to esp_attach below!
   98  */
   99 struct enc_xform *
  100 esp_algorithm_lookup(int alg)
  101 {
  102         if (alg >= ESP_ALG_MAX)
  103                 return NULL;
  104         switch (alg) {
  105         case SADB_EALG_DESCBC:
  106                 return &enc_xform_des;
  107         case SADB_EALG_3DESCBC:
  108                 return &enc_xform_3des;
  109         case SADB_X_EALG_AES:
  110                 return &enc_xform_rijndael128;
  111         case SADB_X_EALG_BLOWFISHCBC:
  112                 return &enc_xform_blf;
  113         case SADB_X_EALG_CAST128CBC:
  114                 return &enc_xform_cast5;
  115         case SADB_X_EALG_SKIPJACK:
  116                 return &enc_xform_skipjack;
  117         case SADB_EALG_NULL:
  118                 return &enc_xform_null;
  119         case SADB_X_EALG_CAMELLIACBC:
  120                 return &enc_xform_camellia;
  121         }
  122         return NULL;
  123 }
  124 
  125 size_t
  126 esp_hdrsiz(struct secasvar *sav)
  127 {
  128         size_t size;
  129 
  130         if (sav != NULL) {
  131                 /*XXX not right for null algorithm--does it matter??*/
  132                 IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
  133                         ("SA with null xform"));
  134                 if (sav->flags & SADB_X_EXT_OLD)
  135                         size = sizeof (struct esp);
  136                 else
  137                         size = sizeof (struct newesp);
  138                 size += sav->tdb_encalgxform->blocksize + 9;
  139                 /*XXX need alg check???*/
  140                 if (sav->tdb_authalgxform != NULL && sav->replay)
  141                         size += ah_hdrsiz(sav);
  142         } else {
  143                 /*
  144                  *   base header size
  145                  * + max iv length for CBC mode
  146                  * + max pad length
  147                  * + sizeof (pad length field)
  148                  * + sizeof (next header field)
  149                  * + max icv supported.
  150                  */
  151                 size = sizeof (struct newesp) + V_esp_max_ivlen + 9 + 16;
  152         }
  153         return size;
  154 }
  155 
  156 /*
  157  * esp_init() is called when an SPI is being set up.
  158  */
  159 static int
  160 esp_init(struct secasvar *sav, struct xformsw *xsp)
  161 {
  162         struct enc_xform *txform;
  163         struct cryptoini cria, crie;
  164         int keylen;
  165         int error;
  166 
  167         txform = esp_algorithm_lookup(sav->alg_enc);
  168         if (txform == NULL) {
  169                 DPRINTF(("%s: unsupported encryption algorithm %d\n",
  170                         __func__, sav->alg_enc));
  171                 return EINVAL;
  172         }
  173         if (sav->key_enc == NULL) {
  174                 DPRINTF(("%s: no encoding key for %s algorithm\n",
  175                          __func__, txform->name));
  176                 return EINVAL;
  177         }
  178         if ((sav->flags&(SADB_X_EXT_OLD|SADB_X_EXT_IV4B)) == SADB_X_EXT_IV4B) {
  179                 DPRINTF(("%s: 4-byte IV not supported with protocol\n",
  180                         __func__));
  181                 return EINVAL;
  182         }
  183         keylen = _KEYLEN(sav->key_enc);
  184         if (txform->minkey > keylen || keylen > txform->maxkey) {
  185                 DPRINTF(("%s: invalid key length %u, must be in the range "
  186                         "[%u..%u] for algorithm %s\n", __func__,
  187                         keylen, txform->minkey, txform->maxkey,
  188                         txform->name));
  189                 return EINVAL;
  190         }
  191 
  192         /*
  193          * NB: The null xform needs a non-zero blocksize to keep the
  194          *      crypto code happy but if we use it to set ivlen then
  195          *      the ESP header will be processed incorrectly.  The
  196          *      compromise is to force it to zero here.
  197          */
  198         sav->ivlen = (txform == &enc_xform_null ? 0 : txform->blocksize);
  199         sav->iv = (caddr_t) malloc(sav->ivlen, M_XDATA, M_WAITOK);
  200         if (sav->iv == NULL) {
  201                 DPRINTF(("%s: no memory for IV\n", __func__));
  202                 return EINVAL;
  203         }
  204         key_randomfill(sav->iv, sav->ivlen);    /*XXX*/
  205 
  206         /*
  207          * Setup AH-related state.
  208          */
  209         if (sav->alg_auth != 0) {
  210                 error = ah_init0(sav, xsp, &cria);
  211                 if (error)
  212                         return error;
  213         }
  214 
  215         /* NB: override anything set in ah_init0 */
  216         sav->tdb_xform = xsp;
  217         sav->tdb_encalgxform = txform;
  218 
  219         /* Initialize crypto session. */
  220         bzero(&crie, sizeof (crie));
  221         crie.cri_alg = sav->tdb_encalgxform->type;
  222         crie.cri_klen = _KEYBITS(sav->key_enc);
  223         crie.cri_key = sav->key_enc->key_data;
  224         /* XXX Rounds ? */
  225 
  226         if (sav->tdb_authalgxform && sav->tdb_encalgxform) {
  227                 /* init both auth & enc */
  228                 crie.cri_next = &cria;
  229                 error = crypto_newsession(&sav->tdb_cryptoid,
  230                                           &crie, V_crypto_support);
  231         } else if (sav->tdb_encalgxform) {
  232                 error = crypto_newsession(&sav->tdb_cryptoid,
  233                                           &crie, V_crypto_support);
  234         } else if (sav->tdb_authalgxform) {
  235                 error = crypto_newsession(&sav->tdb_cryptoid,
  236                                           &cria, V_crypto_support);
  237         } else {
  238                 /* XXX cannot happen? */
  239                 DPRINTF(("%s: no encoding OR authentication xform!\n",
  240                         __func__));
  241                 error = EINVAL;
  242         }
  243         return error;
  244 }
  245 
  246 /*
  247  * Paranoia.
  248  */
  249 static int
  250 esp_zeroize(struct secasvar *sav)
  251 {
  252         /* NB: ah_zerorize free's the crypto session state */
  253         int error = ah_zeroize(sav);
  254 
  255         if (sav->key_enc)
  256                 bzero(sav->key_enc->key_data, _KEYLEN(sav->key_enc));
  257         if (sav->iv) {
  258                 free(sav->iv, M_XDATA);
  259                 sav->iv = NULL;
  260         }
  261         sav->tdb_encalgxform = NULL;
  262         sav->tdb_xform = NULL;
  263         return error;
  264 }
  265 
  266 /*
  267  * ESP input processing, called (eventually) through the protocol switch.
  268  */
  269 static int
  270 esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
  271 {
  272         struct auth_hash *esph;
  273         struct enc_xform *espx;
  274         struct tdb_ident *tdbi;
  275         struct tdb_crypto *tc;
  276         int plen, alen, hlen;
  277         struct m_tag *mtag;
  278         struct newesp *esp;
  279 
  280         struct cryptodesc *crde;
  281         struct cryptop *crp;
  282 
  283         IPSEC_ASSERT(sav != NULL, ("null SA"));
  284         IPSEC_ASSERT(sav->tdb_encalgxform != NULL, ("null encoding xform"));
  285         IPSEC_ASSERT((skip&3) == 0 && (m->m_pkthdr.len&3) == 0,
  286                 ("misaligned packet, skip %u pkt len %u",
  287                         skip, m->m_pkthdr.len));
  288 
  289         /* XXX don't pullup, just copy header */
  290         IP6_EXTHDR_GET(esp, struct newesp *, m, skip, sizeof (struct newesp));
  291 
  292         esph = sav->tdb_authalgxform;
  293         espx = sav->tdb_encalgxform;
  294 
  295         /* Determine the ESP header length */
  296         if (sav->flags & SADB_X_EXT_OLD)
  297                 hlen = sizeof (struct esp) + sav->ivlen;
  298         else
  299                 hlen = sizeof (struct newesp) + sav->ivlen;
  300         /* Authenticator hash size */
  301         alen = esph ? AH_HMAC_HASHLEN : 0;
  302 
  303         /*
  304          * Verify payload length is multiple of encryption algorithm
  305          * block size.
  306          *
  307          * NB: This works for the null algorithm because the blocksize
  308          *     is 4 and all packets must be 4-byte aligned regardless
  309          *     of the algorithm.
  310          */
  311         plen = m->m_pkthdr.len - (skip + hlen + alen);
  312         if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
  313                 DPRINTF(("%s: payload of %d octets not a multiple of %d octets,"
  314                     "  SA %s/%08lx\n", __func__,
  315                     plen, espx->blocksize,
  316                     ipsec_address(&sav->sah->saidx.dst),
  317                     (u_long) ntohl(sav->spi)));
  318                 V_espstat.esps_badilen++;
  319                 m_freem(m);
  320                 return EINVAL;
  321         }
  322 
  323         /*
  324          * Check sequence number.
  325          */
  326         if (esph && sav->replay && !ipsec_chkreplay(ntohl(esp->esp_seq), sav)) {
  327                 DPRINTF(("%s: packet replay check for %s\n", __func__,
  328                     ipsec_logsastr(sav)));      /*XXX*/
  329                 V_espstat.esps_replay++;
  330                 m_freem(m);
  331                 return ENOBUFS;         /*XXX*/
  332         }
  333 
  334         /* Update the counters */
  335         V_espstat.esps_ibytes += m->m_pkthdr.len - (skip + hlen + alen);
  336 
  337         /* Find out if we've already done crypto */
  338         for (mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, NULL);
  339              mtag != NULL;
  340              mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, mtag)) {
  341                 tdbi = (struct tdb_ident *) (mtag + 1);
  342                 if (tdbi->proto == sav->sah->saidx.proto &&
  343                     tdbi->spi == sav->spi &&
  344                     !bcmp(&tdbi->dst, &sav->sah->saidx.dst,
  345                           sizeof(union sockaddr_union)))
  346                         break;
  347         }
  348 
  349         /* Get crypto descriptors */
  350         crp = crypto_getreq(esph && espx ? 2 : 1);
  351         if (crp == NULL) {
  352                 DPRINTF(("%s: failed to acquire crypto descriptors\n",
  353                         __func__));
  354                 V_espstat.esps_crypto++;
  355                 m_freem(m);
  356                 return ENOBUFS;
  357         }
  358 
  359         /* Get IPsec-specific opaque pointer */
  360         if (esph == NULL || mtag != NULL)
  361                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  362                     M_XDATA, M_NOWAIT|M_ZERO);
  363         else
  364                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto) + alen,
  365                     M_XDATA, M_NOWAIT|M_ZERO);
  366         if (tc == NULL) {
  367                 crypto_freereq(crp);
  368                 DPRINTF(("%s: failed to allocate tdb_crypto\n", __func__));
  369                 V_espstat.esps_crypto++;
  370                 m_freem(m);
  371                 return ENOBUFS;
  372         }
  373 
  374         tc->tc_ptr = (caddr_t) mtag;
  375 
  376         if (esph) {
  377                 struct cryptodesc *crda = crp->crp_desc;
  378 
  379                 IPSEC_ASSERT(crda != NULL, ("null ah crypto descriptor"));
  380 
  381                 /* Authentication descriptor */
  382                 crda->crd_skip = skip;
  383                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  384                 crda->crd_inject = m->m_pkthdr.len - alen;
  385 
  386                 crda->crd_alg = esph->type;
  387                 crda->crd_key = sav->key_auth->key_data;
  388                 crda->crd_klen = _KEYBITS(sav->key_auth);
  389 
  390                 /* Copy the authenticator */
  391                 if (mtag == NULL)
  392                         m_copydata(m, m->m_pkthdr.len - alen, alen,
  393                                    (caddr_t) (tc + 1));
  394 
  395                 /* Chain authentication request */
  396                 crde = crda->crd_next;
  397         } else {
  398                 crde = crp->crp_desc;
  399         }
  400 
  401         /* Crypto operation descriptor */
  402         crp->crp_ilen = m->m_pkthdr.len; /* Total input length */
  403         crp->crp_flags = CRYPTO_F_IMBUF | CRYPTO_F_CBIFSYNC;
  404         crp->crp_buf = (caddr_t) m;
  405         crp->crp_callback = esp_input_cb;
  406         crp->crp_sid = sav->tdb_cryptoid;
  407         crp->crp_opaque = (caddr_t) tc;
  408 
  409         /* These are passed as-is to the callback */
  410         tc->tc_spi = sav->spi;
  411         tc->tc_dst = sav->sah->saidx.dst;
  412         tc->tc_proto = sav->sah->saidx.proto;
  413         tc->tc_protoff = protoff;
  414         tc->tc_skip = skip;
  415 
  416         /* Decryption descriptor */
  417         if (espx) {
  418                 IPSEC_ASSERT(crde != NULL, ("null esp crypto descriptor"));
  419                 crde->crd_skip = skip + hlen;
  420                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  421                 crde->crd_inject = skip + hlen - sav->ivlen;
  422 
  423                 crde->crd_alg = espx->type;
  424                 crde->crd_key = sav->key_enc->key_data;
  425                 crde->crd_klen = _KEYBITS(sav->key_enc);
  426                 /* XXX Rounds ? */
  427         }
  428 
  429         if (mtag == NULL)
  430                 return crypto_dispatch(crp);
  431         else
  432                 return esp_input_cb(crp);
  433 }
  434 
  435 #ifdef INET6
  436 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag) do {              \
  437         if (saidx->dst.sa.sa_family == AF_INET6) {                           \
  438                 error = ipsec6_common_input_cb(m, sav, skip, protoff, mtag); \
  439         } else {                                                             \
  440                 error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag); \
  441         }                                                                    \
  442 } while (0)
  443 #else
  444 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag)                   \
  445         (error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag))
  446 #endif
  447 
  448 /*
  449  * ESP input callback from the crypto driver.
  450  */
  451 static int
  452 esp_input_cb(struct cryptop *crp)
  453 {
  454         u_int8_t lastthree[3], aalg[AH_HMAC_HASHLEN];
  455         int hlen, skip, protoff, error;
  456         struct mbuf *m;
  457         struct cryptodesc *crd;
  458         struct auth_hash *esph;
  459         struct enc_xform *espx;
  460         struct tdb_crypto *tc;
  461         struct m_tag *mtag;
  462         struct secasvar *sav;
  463         struct secasindex *saidx;
  464         caddr_t ptr;
  465 
  466         crd = crp->crp_desc;
  467         IPSEC_ASSERT(crd != NULL, ("null crypto descriptor!"));
  468 
  469         tc = (struct tdb_crypto *) crp->crp_opaque;
  470         IPSEC_ASSERT(tc != NULL, ("null opaque crypto data area!"));
  471         skip = tc->tc_skip;
  472         protoff = tc->tc_protoff;
  473         mtag = (struct m_tag *) tc->tc_ptr;
  474         m = (struct mbuf *) crp->crp_buf;
  475 
  476         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi);
  477         if (sav == NULL) {
  478                 V_espstat.esps_notdb++;
  479                 DPRINTF(("%s: SA gone during crypto (SA %s/%08lx proto %u)\n",
  480                     __func__, ipsec_address(&tc->tc_dst),
  481                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  482                 error = ENOBUFS;                /*XXX*/
  483                 goto bad;
  484         }
  485 
  486         saidx = &sav->sah->saidx;
  487         IPSEC_ASSERT(saidx->dst.sa.sa_family == AF_INET ||
  488                 saidx->dst.sa.sa_family == AF_INET6,
  489                 ("unexpected protocol family %u", saidx->dst.sa.sa_family));
  490 
  491         esph = sav->tdb_authalgxform;
  492         espx = sav->tdb_encalgxform;
  493 
  494         /* Check for crypto errors */
  495         if (crp->crp_etype) {
  496                 /* Reset the session ID */
  497                 if (sav->tdb_cryptoid != 0)
  498                         sav->tdb_cryptoid = crp->crp_sid;
  499 
  500                 if (crp->crp_etype == EAGAIN) {
  501                         KEY_FREESAV(&sav);
  502                         error = crypto_dispatch(crp);
  503                         return error;
  504                 }
  505 
  506                 V_espstat.esps_noxform++;
  507                 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
  508                 error = crp->crp_etype;
  509                 goto bad;
  510         }
  511 
  512         /* Shouldn't happen... */
  513         if (m == NULL) {
  514                 V_espstat.esps_crypto++;
  515                 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
  516                 error = EINVAL;
  517                 goto bad;
  518         }
  519         V_espstat.esps_hist[sav->alg_enc]++;
  520 
  521         /* If authentication was performed, check now. */
  522         if (esph != NULL) {
  523                 /*
  524                  * If we have a tag, it means an IPsec-aware NIC did
  525                  * the verification for us.  Otherwise we need to
  526                  * check the authentication calculation.
  527                  */
  528                 V_ahstat.ahs_hist[sav->alg_auth]++;
  529                 if (mtag == NULL) {
  530                         /* Copy the authenticator from the packet */
  531                         m_copydata(m, m->m_pkthdr.len - AH_HMAC_HASHLEN,
  532                                 AH_HMAC_HASHLEN, aalg);
  533 
  534                         ptr = (caddr_t) (tc + 1);
  535 
  536                         /* Verify authenticator */
  537                         if (bcmp(ptr, aalg, AH_HMAC_HASHLEN) != 0) {
  538                                 DPRINTF(("%s: "
  539                     "authentication hash mismatch for packet in SA %s/%08lx\n",
  540                                     __func__,
  541                                     ipsec_address(&saidx->dst),
  542                                     (u_long) ntohl(sav->spi)));
  543                                 V_espstat.esps_badauth++;
  544                                 error = EACCES;
  545                                 goto bad;
  546                         }
  547                 }
  548 
  549                 /* Remove trailing authenticator */
  550                 m_adj(m, -AH_HMAC_HASHLEN);
  551         }
  552 
  553         /* Release the crypto descriptors */
  554         free(tc, M_XDATA), tc = NULL;
  555         crypto_freereq(crp), crp = NULL;
  556 
  557         /*
  558          * Packet is now decrypted.
  559          */
  560         m->m_flags |= M_DECRYPTED;
  561 
  562         /*
  563          * Update replay sequence number, if appropriate.
  564          */
  565         if (sav->replay) {
  566                 u_int32_t seq;
  567 
  568                 m_copydata(m, skip + offsetof(struct newesp, esp_seq),
  569                            sizeof (seq), (caddr_t) &seq);
  570                 if (ipsec_updatereplay(ntohl(seq), sav)) {
  571                         DPRINTF(("%s: packet replay check for %s\n", __func__,
  572                             ipsec_logsastr(sav)));
  573                         V_espstat.esps_replay++;
  574                         error = ENOBUFS;
  575                         goto bad;
  576                 }
  577         }
  578 
  579         /* Determine the ESP header length */
  580         if (sav->flags & SADB_X_EXT_OLD)
  581                 hlen = sizeof (struct esp) + sav->ivlen;
  582         else
  583                 hlen = sizeof (struct newesp) + sav->ivlen;
  584 
  585         /* Remove the ESP header and IV from the mbuf. */
  586         error = m_striphdr(m, skip, hlen);
  587         if (error) {
  588                 V_espstat.esps_hdrops++;
  589                 DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__,
  590                     ipsec_address(&sav->sah->saidx.dst),
  591                     (u_long) ntohl(sav->spi)));
  592                 goto bad;
  593         }
  594 
  595         /* Save the last three bytes of decrypted data */
  596         m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);
  597 
  598         /* Verify pad length */
  599         if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
  600                 V_espstat.esps_badilen++;
  601                 DPRINTF(("%s: invalid padding length %d for %u byte packet "
  602                         "in SA %s/%08lx\n", __func__,
  603                          lastthree[1], m->m_pkthdr.len - skip,
  604                          ipsec_address(&sav->sah->saidx.dst),
  605                          (u_long) ntohl(sav->spi)));
  606                 error = EINVAL;
  607                 goto bad;
  608         }
  609 
  610         /* Verify correct decryption by checking the last padding bytes */
  611         if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
  612                 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
  613                         V_espstat.esps_badenc++;
  614                         DPRINTF(("%s: decryption failed for packet in "
  615                                 "SA %s/%08lx\n", __func__,
  616                                 ipsec_address(&sav->sah->saidx.dst),
  617                                 (u_long) ntohl(sav->spi)));
  618                         error = EINVAL;
  619                         goto bad;
  620                 }
  621         }
  622 
  623         /* Trim the mbuf chain to remove trailing authenticator and padding */
  624         m_adj(m, -(lastthree[1] + 2));
  625 
  626         /* Restore the Next Protocol field */
  627         m_copyback(m, protoff, sizeof (u_int8_t), lastthree + 2);
  628 
  629         IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag);
  630 
  631         KEY_FREESAV(&sav);
  632         return error;
  633 bad:
  634         if (sav)
  635                 KEY_FREESAV(&sav);
  636         if (m != NULL)
  637                 m_freem(m);
  638         if (tc != NULL)
  639                 free(tc, M_XDATA);
  640         if (crp != NULL)
  641                 crypto_freereq(crp);
  642         return error;
  643 }
  644 
  645 /*
  646  * ESP output routine, called by ipsec[46]_process_packet().
  647  */
  648 static int
  649 esp_output(
  650         struct mbuf *m,
  651         struct ipsecrequest *isr,
  652         struct mbuf **mp,
  653         int skip,
  654         int protoff
  655 )
  656 {
  657         struct enc_xform *espx;
  658         struct auth_hash *esph;
  659         int hlen, rlen, plen, padding, blks, alen, i, roff;
  660         struct mbuf *mo = (struct mbuf *) NULL;
  661         struct tdb_crypto *tc;
  662         struct secasvar *sav;
  663         struct secasindex *saidx;
  664         unsigned char *pad;
  665         u_int8_t prot;
  666         int error, maxpacketsize;
  667 
  668         struct cryptodesc *crde = NULL, *crda = NULL;
  669         struct cryptop *crp;
  670 
  671         sav = isr->sav;
  672         IPSEC_ASSERT(sav != NULL, ("null SA"));
  673         esph = sav->tdb_authalgxform;
  674         espx = sav->tdb_encalgxform;
  675         IPSEC_ASSERT(espx != NULL, ("null encoding xform"));
  676 
  677         if (sav->flags & SADB_X_EXT_OLD)
  678                 hlen = sizeof (struct esp) + sav->ivlen;
  679         else
  680                 hlen = sizeof (struct newesp) + sav->ivlen;
  681 
  682         rlen = m->m_pkthdr.len - skip;  /* Raw payload length. */
  683         /*
  684          * NB: The null encoding transform has a blocksize of 4
  685          *     so that headers are properly aligned.
  686          */
  687         blks = espx->blocksize;         /* IV blocksize */
  688 
  689         /* XXX clamp padding length a la KAME??? */
  690         padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;
  691         plen = rlen + padding;          /* Padded payload length. */
  692 
  693         if (esph)
  694                 alen = AH_HMAC_HASHLEN;
  695         else
  696                 alen = 0;
  697 
  698         V_espstat.esps_output++;
  699 
  700         saidx = &sav->sah->saidx;
  701         /* Check for maximum packet size violations. */
  702         switch (saidx->dst.sa.sa_family) {
  703 #ifdef INET
  704         case AF_INET:
  705                 maxpacketsize = IP_MAXPACKET;
  706                 break;
  707 #endif /* INET */
  708 #ifdef INET6
  709         case AF_INET6:
  710                 maxpacketsize = IPV6_MAXPACKET;
  711                 break;
  712 #endif /* INET6 */
  713         default:
  714                 DPRINTF(("%s: unknown/unsupported protocol "
  715                     "family %d, SA %s/%08lx\n", __func__,
  716                     saidx->dst.sa.sa_family, ipsec_address(&saidx->dst),
  717                     (u_long) ntohl(sav->spi)));
  718                 V_espstat.esps_nopf++;
  719                 error = EPFNOSUPPORT;
  720                 goto bad;
  721         }
  722         if (skip + hlen + rlen + padding + alen > maxpacketsize) {
  723                 DPRINTF(("%s: packet in SA %s/%08lx got too big "
  724                     "(len %u, max len %u)\n", __func__,
  725                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi),
  726                     skip + hlen + rlen + padding + alen, maxpacketsize));
  727                 V_espstat.esps_toobig++;
  728                 error = EMSGSIZE;
  729                 goto bad;
  730         }
  731 
  732         /* Update the counters. */
  733         V_espstat.esps_obytes += m->m_pkthdr.len - skip;
  734 
  735         m = m_unshare(m, M_NOWAIT);
  736         if (m == NULL) {
  737                 DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__,
  738                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  739                 V_espstat.esps_hdrops++;
  740                 error = ENOBUFS;
  741                 goto bad;
  742         }
  743 
  744         /* Inject ESP header. */
  745         mo = m_makespace(m, skip, hlen, &roff);
  746         if (mo == NULL) {
  747                 DPRINTF(("%s: %u byte ESP hdr inject failed for SA %s/%08lx\n",
  748                     __func__, hlen, ipsec_address(&saidx->dst),
  749                     (u_long) ntohl(sav->spi)));
  750                 V_espstat.esps_hdrops++;                /* XXX diffs from openbsd */
  751                 error = ENOBUFS;
  752                 goto bad;
  753         }
  754 
  755         /* Initialize ESP header. */
  756         bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff, sizeof(u_int32_t));
  757         if (sav->replay) {
  758                 u_int32_t replay;
  759 
  760 #ifdef REGRESSION
  761                 /* Emulate replay attack when ipsec_replay is TRUE. */
  762                 if (!V_ipsec_replay)
  763 #endif
  764                         sav->replay->count++;
  765                 replay = htonl(sav->replay->count);
  766                 bcopy((caddr_t) &replay,
  767                     mtod(mo, caddr_t) + roff + sizeof(u_int32_t),
  768                     sizeof(u_int32_t));
  769         }
  770 
  771         /*
  772          * Add padding -- better to do it ourselves than use the crypto engine,
  773          * although if/when we support compression, we'd have to do that.
  774          */
  775         pad = (u_char *) m_pad(m, padding + alen);
  776         if (pad == NULL) {
  777                 DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__,
  778                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  779                 m = NULL;               /* NB: free'd by m_pad */
  780                 error = ENOBUFS;
  781                 goto bad;
  782         }
  783 
  784         /*
  785          * Add padding: random, zero, or self-describing.
  786          * XXX catch unexpected setting
  787          */
  788         switch (sav->flags & SADB_X_EXT_PMASK) {
  789         case SADB_X_EXT_PRAND:
  790                 (void) read_random(pad, padding - 2);
  791                 break;
  792         case SADB_X_EXT_PZERO:
  793                 bzero(pad, padding - 2);
  794                 break;
  795         case SADB_X_EXT_PSEQ:
  796                 for (i = 0; i < padding - 2; i++)
  797                         pad[i] = i+1;
  798                 break;
  799         }
  800 
  801         /* Fix padding length and Next Protocol in padding itself. */
  802         pad[padding - 2] = padding - 2;
  803         m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);
  804 
  805         /* Fix Next Protocol in IPv4/IPv6 header. */
  806         prot = IPPROTO_ESP;
  807         m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);
  808 
  809         /* Get crypto descriptors. */
  810         crp = crypto_getreq(esph && espx ? 2 : 1);
  811         if (crp == NULL) {
  812                 DPRINTF(("%s: failed to acquire crypto descriptors\n",
  813                         __func__));
  814                 V_espstat.esps_crypto++;
  815                 error = ENOBUFS;
  816                 goto bad;
  817         }
  818 
  819         if (espx) {
  820                 crde = crp->crp_desc;
  821                 crda = crde->crd_next;
  822 
  823                 /* Encryption descriptor. */
  824                 crde->crd_skip = skip + hlen;
  825                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  826                 crde->crd_flags = CRD_F_ENCRYPT;
  827                 crde->crd_inject = skip + hlen - sav->ivlen;
  828 
  829                 /* Encryption operation. */
  830                 crde->crd_alg = espx->type;
  831                 crde->crd_key = sav->key_enc->key_data;
  832                 crde->crd_klen = _KEYBITS(sav->key_enc);
  833                 /* XXX Rounds ? */
  834         } else
  835                 crda = crp->crp_desc;
  836 
  837         /* IPsec-specific opaque crypto info. */
  838         tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  839                 M_XDATA, M_NOWAIT|M_ZERO);
  840         if (tc == NULL) {
  841                 crypto_freereq(crp);
  842                 DPRINTF(("%s: failed to allocate tdb_crypto\n", __func__));
  843                 V_espstat.esps_crypto++;
  844                 error = ENOBUFS;
  845                 goto bad;
  846         }
  847 
  848         /* Callback parameters */
  849         tc->tc_isr = isr;
  850         tc->tc_spi = sav->spi;
  851         tc->tc_dst = saidx->dst;
  852         tc->tc_proto = saidx->proto;
  853 
  854         /* Crypto operation descriptor. */
  855         crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
  856         crp->crp_flags = CRYPTO_F_IMBUF | CRYPTO_F_CBIFSYNC;
  857         crp->crp_buf = (caddr_t) m;
  858         crp->crp_callback = esp_output_cb;
  859         crp->crp_opaque = (caddr_t) tc;
  860         crp->crp_sid = sav->tdb_cryptoid;
  861 
  862         if (esph) {
  863                 /* Authentication descriptor. */
  864                 crda->crd_skip = skip;
  865                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  866                 crda->crd_inject = m->m_pkthdr.len - alen;
  867 
  868                 /* Authentication operation. */
  869                 crda->crd_alg = esph->type;
  870                 crda->crd_key = sav->key_auth->key_data;
  871                 crda->crd_klen = _KEYBITS(sav->key_auth);
  872         }
  873 
  874         return crypto_dispatch(crp);
  875 bad:
  876         if (m)
  877                 m_freem(m);
  878         return (error);
  879 }
  880 
  881 /*
  882  * ESP output callback from the crypto driver.
  883  */
  884 static int
  885 esp_output_cb(struct cryptop *crp)
  886 {
  887         struct tdb_crypto *tc;
  888         struct ipsecrequest *isr;
  889         struct secasvar *sav;
  890         struct mbuf *m;
  891         int err, error;
  892 
  893         tc = (struct tdb_crypto *) crp->crp_opaque;
  894         IPSEC_ASSERT(tc != NULL, ("null opaque data area!"));
  895         m = (struct mbuf *) crp->crp_buf;
  896 
  897         isr = tc->tc_isr;
  898         IPSECREQUEST_LOCK(isr);
  899         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi);
  900         if (sav == NULL) {
  901                 V_espstat.esps_notdb++;
  902                 DPRINTF(("%s: SA gone during crypto (SA %s/%08lx proto %u)\n",
  903                     __func__, ipsec_address(&tc->tc_dst),
  904                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  905                 error = ENOBUFS;                /*XXX*/
  906                 goto bad;
  907         }
  908         IPSEC_ASSERT(isr->sav == sav,
  909                 ("SA changed was %p now %p\n", isr->sav, sav));
  910 
  911         /* Check for crypto errors. */
  912         if (crp->crp_etype) {
  913                 /* Reset session ID. */
  914                 if (sav->tdb_cryptoid != 0)
  915                         sav->tdb_cryptoid = crp->crp_sid;
  916 
  917                 if (crp->crp_etype == EAGAIN) {
  918                         KEY_FREESAV(&sav);
  919                         IPSECREQUEST_UNLOCK(isr);
  920                         error = crypto_dispatch(crp);
  921                         return error;
  922                 }
  923 
  924                 V_espstat.esps_noxform++;
  925                 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
  926                 error = crp->crp_etype;
  927                 goto bad;
  928         }
  929 
  930         /* Shouldn't happen... */
  931         if (m == NULL) {
  932                 V_espstat.esps_crypto++;
  933                 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
  934                 error = EINVAL;
  935                 goto bad;
  936         }
  937         V_espstat.esps_hist[sav->alg_enc]++;
  938         if (sav->tdb_authalgxform != NULL)
  939                 V_ahstat.ahs_hist[sav->alg_auth]++;
  940 
  941         /* Release crypto descriptors. */
  942         free(tc, M_XDATA);
  943         crypto_freereq(crp);
  944 
  945 #ifdef REGRESSION
  946         /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
  947         if (V_ipsec_integrity) {
  948                 static unsigned char ipseczeroes[AH_HMAC_HASHLEN];
  949                 struct auth_hash *esph;
  950 
  951                 /*
  952                  * Corrupt HMAC if we want to test integrity verification of
  953                  * the other side.
  954                  */
  955                 esph = sav->tdb_authalgxform;
  956                 if (esph !=  NULL) {
  957                         m_copyback(m, m->m_pkthdr.len - AH_HMAC_HASHLEN,
  958                             AH_HMAC_HASHLEN, ipseczeroes);
  959                 }
  960         }
  961 #endif
  962 
  963         /* NB: m is reclaimed by ipsec_process_done. */
  964         err = ipsec_process_done(m, isr);
  965         KEY_FREESAV(&sav);
  966         IPSECREQUEST_UNLOCK(isr);
  967         return err;
  968 bad:
  969         if (sav)
  970                 KEY_FREESAV(&sav);
  971         IPSECREQUEST_UNLOCK(isr);
  972         if (m)
  973                 m_freem(m);
  974         free(tc, M_XDATA);
  975         crypto_freereq(crp);
  976         return error;
  977 }
  978 
  979 static struct xformsw esp_xformsw = {
  980         XF_ESP,         XFT_CONF|XFT_AUTH,      "IPsec ESP",
  981         esp_init,       esp_zeroize,            esp_input,
  982         esp_output
  983 };
  984 
  985 static void
  986 esp_attach(void)
  987 {
  988 #define MAXIV(xform)                                    \
  989         if (xform.blocksize > V_esp_max_ivlen)          \
  990                 V_esp_max_ivlen = xform.blocksize       \
  991 
  992         MAXIV(enc_xform_des);           /* SADB_EALG_DESCBC */
  993         MAXIV(enc_xform_3des);          /* SADB_EALG_3DESCBC */
  994         MAXIV(enc_xform_rijndael128);   /* SADB_X_EALG_AES */
  995         MAXIV(enc_xform_blf);           /* SADB_X_EALG_BLOWFISHCBC */
  996         MAXIV(enc_xform_cast5);         /* SADB_X_EALG_CAST128CBC */
  997         MAXIV(enc_xform_skipjack);      /* SADB_X_EALG_SKIPJACK */
  998         MAXIV(enc_xform_null);          /* SADB_EALG_NULL */
  999         MAXIV(enc_xform_camellia);      /* SADB_X_EALG_CAMELLIACBC */
 1000 
 1001         xform_register(&esp_xformsw);
 1002 #undef MAXIV
 1003 }
 1004 SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, esp_attach, NULL);

Cache object: 2f97be16a3d4fbb25e4642e2047d706b


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